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Polymeric foam

Polymeric foams are multiphase cellular materials consisting of a solid polymer matrix interspersed with gas-filled voids, resulting in low-density structures that exhibit high specific strength, thermal and acoustic insulation, and energy absorption capabilities.^[1]^[2] These foams are produced through processes that incorporate blowing agents to create either open-cell configurations, where voids interconnect for permeability, or closed-cell variants, which trap gas for enhanced buoyancy and barrier properties.^[2]^[3] Common polymer bases include polyurethane (PU), polystyrene (PS), polyvinyl chloride (PVC), polypropylene (PP), and polyethylene (PE), with PU dominating due to its versatility in both flexible and rigid forms.^[3] Thermoplastic foams, such as those from PS and PE, allow reprocessing, while thermoset types like PU provide greater rigidity and fire resistance but are irreversible.^[4] Key properties stem from their microstructure: densities often below 100 kg/m³ enable lightweighting in transportation, while the cellular architecture dissipates mechanical energy effectively, making them suitable for impact protection in sports equipment and automotive parts.^[5]^[6] Applications span construction for insulation panels, packaging for shock absorption, furniture cushioning, and advanced uses in aerospace composites and biomedical scaffolds, driven by empirical advantages in weight reduction and functional performance over denser alternatives.^[3]^[2] Despite environmental scrutiny over persistence and production emissions, innovations in bio-based polymers and recycling continue to expand their utility without compromising core mechanical benefits.^[6]^[7]

Fundamentals

Definition and Structure

Polymeric foams are multiphase materials composed of a continuous solid polymer matrix interspersed with a discontinuous gaseous phase, forming a cellular architecture that imparts low density and unique mechanical properties.^[8] The gas phase, often introduced via blowing agents during processing, occupies a substantial volume fraction, typically resulting in foam densities orders of magnitude lower than the base polymer, such as 10-200 kg/m³ for common rigid polyurethane foams.^[9] This structure arises from nucleation, growth, and stabilization of gas bubbles within the polymer melt or solution, governed by thermodynamic instability and viscoelastic response of the polymer.^[10] The fundamental structural feature of polymeric foams is their cellular morphology, characterized by the size, shape, distribution, and interconnectivity of cells. Cell diameters range from nanometers in microcellular foams (e.g., 0.1-10 μm for enhanced toughness applications) to hundreds of micrometers in macrocellular variants, with cell density often exceeding 10^9 cells/cm³ in fine structures.^[11] Foams are broadly classified by cell openness: open-cell structures feature interconnected voids resembling a reticular network of struts and thin membranes, enabling gas or liquid permeation and high compressibility, as seen in flexible polyurethane foams used for cushioning.^[8] In contrast, closed-cell foams consist of isolated, spherical or polyhedral gas pockets enclosed by intact polymer walls, conferring impermeability to fluids, higher stiffness, and buoyancy, exemplified by extruded polystyrene insulation boards.^[12]^[13] Hierarchical morphologies, combining multi-scale cells (e.g., macrocells >100 μm enclosing microcells 1-100 μm), further tailor properties like energy absorption by optimizing strut thickness and wall integrity.^[14] The relative volume of solid polymer in cell walls versus struts influences load-bearing behavior, with uniform nucleation yielding isotropic structures superior for structural applications.^[15]

Classification by Polymer Type and Morphology

Polymeric foams are broadly classified by the chemical nature of the base polymer into thermoplastic and thermoset types, with the former exhibiting reversible softening upon heating for potential reprocessing and the latter featuring irreversible cross-linking that imparts permanent rigidity post-cure. Thermoplastic foams, derived from linear or branched polymers such as polystyrene (PS), polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC), constitute a significant portion of extruded and bead foams used in packaging and insulation due to their processability and recyclability potential.^[8] ^[3] Thermoset foams, formed from reactive precursors like polyurethane (PU), phenolic resins, epoxy, and polyimide, undergo chemical curing that results in highly cross-linked networks, enabling superior thermal resistance and structural integrity but limiting recyclability.^[3] ^[8] Morphological classification focuses on cellular structure, primarily distinguishing open-cell from closed-cell foams based on cell interconnectivity and wall integrity, which directly influence permeability, mechanical behavior, and end-use suitability. Open-cell foams feature interconnected pores where cell walls are ruptured or absent, permitting gas or liquid flow through the matrix; this structure predominates in flexible applications like cushioning and filtration, as seen in low-density PU foams with densities around 20-50 kg/m³.^[6] ^[2] Closed-cell foams maintain sealed, discrete cells with intact polymer walls encapsulating the blowing gas, yielding low permeability, enhanced buoyancy, and superior thermal insulation; examples include rigid PS and PU foams with cell sizes typically 0.1-1 mm and densities from 30-100 kg/m³.^[16] ^[3] These classifications often intersect, as polymer type influences achievable morphology—for instance, thermoplastic foams like PS tend toward uniform closed cells via physical blowing, while thermoset PU can yield either open cells in flexible variants (via water-based reactions producing CO₂) or closed cells in rigid forms (using physical agents like pentane).^[8] Additional morphological descriptors include cell size distribution (uniform vs. bimodal), anisotropy (elongated cells in extruded foams), and overall foam density, which ranges from microcellular (<100 µm cells, densities >0.4 g/cm³) to syntactic foams incorporating hollow microspheres for hybrid structures.^[17] Rigid foams generally exhibit higher modulus due to thicker struts and closed morphology, contrasting with flexible foams' elastomeric deformation via thin, bending walls.^[2]

Historical Development

Origins and Early Innovations

The earliest polymeric foams emerged from vulcanized rubber, with commercial sponge rubber foam—a flexible, open-cell material—first produced around 1910 through processes involving chemical blowing agents to create gas bubbles within the polymer matrix.^[2] This innovation built on Charles Goodyear's 1839 vulcanization of natural rubber, enabling the formation of cellular structures for applications like seals and cushions, though production remained labor-intensive and limited in scale until mechanical foaming techniques advanced.^[2] A significant leap occurred in 1931 when Swedish engineers Carl Munters and Axel Tandberg developed the first synthetic polymer foam using polystyrene, aerating the molten resin with pentane gas to produce lightweight, closed-cell rigid foam suitable for thermal insulation.^[18] This process, patented as a method for creating low-density cellular plastics, addressed limitations of rubber foams by offering better thermal stability and manufacturability, laying groundwork for expanded polystyrene (EPS) variants.^[18] Polyurethane foams originated with Otto Bayer's 1937 synthesis of polyurethane polymers at IG Farben in Germany, via the reaction of polyols with diisocyanates, which inadvertently produced foamed structures when volatile components expanded during curing.^[19] Initial rigid polyurethane foams, developed in the late 1930s and early 1940s, demonstrated superior insulation properties compared to earlier foams, with patents for flexible variants emerging by 1942 through one-step processes using water as a blowing agent to generate carbon dioxide.^[8] These innovations prioritized chemical foaming mechanisms over mechanical ones, enabling tunable densities and morphologies essential for emerging industrial uses.^[8]

Post-War Commercialization and Growth

Following World War II, the commercialization of polymeric foams accelerated, building on wartime innovations in materials like polyurethane, which had been developed by Otto Bayer's team at IG Farben in 1937 for applications such as coatings and rigid structures.^[20] In the United States, the first commercial production of rigid polyurethane foam occurred in 1953, primarily for thermal insulation in buildings and appliances, driven by its low density and insulating properties.^[21] Flexible polyurethane foam followed shortly, with initial commercial output in Europe in 1954 using polyester polyols, enabling broader adoption in cushioning and furniture; polyether polyols, which improved flexibility and durability, were introduced in the late 1950s, further spurring U.S. production.^[22]^[20] Parallel developments in polystyrene foams contributed to post-war expansion. Expanded polystyrene (EPS), leveraging pre-war polystyrene synthesis, saw production surge after 1945 to meet demands for lightweight packaging and insulation, with its cellular structure providing buoyancy and thermal resistance ideal for consumer goods and construction.^[23] The overall plastics industry, including foams, experienced annual growth exceeding 15% from 1946 to 1960, as wartime shortages resolved and synthetic materials replaced scarcer natural alternatives like rubber and wood.^[24] By 1960, global plastic production volumes had surpassed aluminum, with foams playing a pivotal role in sectors such as automotive seating, mattresses, and protective packaging due to their cost-effectiveness and versatility.^[24]^[25] This growth was fueled by innovations from firms like Union Carbide, which advanced polyurethane formulations from the early 1950s onward, enabling scalable slabstock and molded foam processes for mass markets.^[26] Applications diversified rapidly: rigid foams insulated refrigerators and homes, while flexible variants cushioned vehicle seats and furniture, reducing reliance on traditional fillings and lowering manufacturing costs.^[27] Economic recovery in Europe and North America, coupled with rising consumer demand for affordable synthetics, propelled the sector, though early limitations in fire resistance and environmental stability prompted ongoing refinements in additives and blowing agents.^[1] By the mid-1950s, polyurethane foams were integral to spray applications for roofing and cavity filling, marking the transition from niche to ubiquitous materials.^[28]

Production Methods

Core Foaming Techniques

Core foaming techniques for polymeric foams encompass processing methods that generate gas within or introduce gas to a polymer matrix, resulting in cellular structures with void fractions typically ranging from 30% to 99%. These techniques are broadly classified by their operational mode—batch, continuous, or reactive—and leverage physical, chemical, or mechanical principles to nucleate, grow, and stabilize cells. Batch foaming, extrusion foaming, injection foam molding, and bead foaming represent the primary approaches for thermoplastics, while reactive foaming predominates for thermosets like polyurethanes.^[6]^[29] Batch foaming entails saturating a polymer sample, often in pellet or sheet form, with a physical blowing agent such as supercritical CO₂ or N₂ under elevated pressure (e.g., 5–30 MPa) and temperature in a pressure vessel, followed by rapid depressurization to induce supersaturation, heterogeneous nucleation on impurities or additives, and cell expansion until stabilization by crystallization or vitrification. This discontinuous method yields foams with controlled cell sizes (down to micrometers) and densities as low as 0.05 g/cm³, making it ideal for laboratory-scale optimization and polymers like polystyrene (PS), polypropylene (PP), and polylactide (PLA); for instance, CO₂-saturated PS achieves uniform microcellular structures with cell densities exceeding 10^9 cells/cm³. Advantages include precise morphological tuning via saturation time (hours to days) and pressure drop rate, though scalability is limited by batch size.^[6] Extrusion foaming operates continuously by feeding polymer resin into a twin-screw extruder, where it melts (typically 150–250°C), incorporates a blowing agent (e.g., 3–6 wt% supercritical CO₂ injected at 10–20 MPa), mixes homogeneously to reduce viscosity by up to 50%, and extrudes through a die with a sudden pressure drop (from ~20 MPa to atmospheric), triggering nucleation and growth in a cooling medium like air or water. This produces sheets, rods, or profiles with high throughput (up to tons/hour) and cell densities of 10^8–10^10 cells/cm³, suited for PP, PLA, and polyethylene (PE); examples include PLA-clay nanocomposites yielding foams with expansion ratios of 10–20. Challenges involve managing die swell, melt fracture, and uneven cooling to prevent cell coalescence, often addressed by nucleating agents like talc (1–5 wt%).^[6]^[29] Injection foam molding adapts conventional injection molding by plasticizing polymer with a metered blowing agent (e.g., N₂ at 1–5 wt%) in the barrel, injecting the frothy melt into a mold at high speed (50–200 cm³/s) and pressure (50–150 MPa), where core expansion fills the cavity upon pressure relaxation, followed by mold cooling at 20–100°C. It generates lightweight parts with surface skins and core foams, achieving 20–50% weight reduction and densities of 0.2–0.6 g/cm³, commonly for PP, polyamide 6 (PA6), and PS; microcellular PP/PTFE foams, for example, exhibit tensile strengths up to 30 MPa. Key parameters include shot size (80–100% fill) and mold temperature to balance skin thickness (0.5–2 mm) and cell uniformity, with simulations mitigating warpage from differential shrinkage.^[6]^[29] Bead foaming, distinct for its pre-expanded particles, involves impregnating expandable beads (e.g., PS with pentane core, 5–10 wt%) under pressure, then steaming or heating to 90–120°C for rapid expansion (up to 50-fold volume increase via gas diffusion), followed by fusion in molds under steam (1–2 bar) or pressure. This yields molded foams like expanded polystyrene (EPS) with densities of 15–30 kg/m³ and closed-cell morphologies for insulation. Polymers such as PE and PP are used, with advantages in complex shapes but limitations in inter-bead bonding strength (improved by coatings).^[6] For thermosetting foams, reactive foaming dominates, particularly for polyurethanes, where isocyanates react with polyols and water (or additives) in a one-shot mix (e.g., via high-pressure impingement at 100–2000 psi), generating CO₂ in situ (up to 40 L/kg) during gelation and cure at ambient or elevated temperatures, forming slabstock or molded articles with densities of 20–100 kg/m³. This chemical process integrates polymerization and foaming, enabling flexible (open-cell) or rigid (closed-cell) variants, though it requires precise stoichiometry to avoid defects like voids. Mechanical foaming, a simpler variant, whips air into viscous resins (e.g., epoxy or phenolic) via high-shear mixing (1000–5000 rpm) before curing, producing open-cell foams without chemical agents but with coarser cells (millimeters).^[6]

Role of Blowing Agents and Additives

Blowing agents are substances incorporated into the polymer melt or precursor to generate gas, thereby expanding the material into a cellular structure during foaming processes such as extrusion, injection molding, or reactive polymerization.^[30] They primarily influence foam density, cell size distribution, and morphology by controlling nucleation sites, bubble growth, and stabilization, with typical expansion ratios yielding densities from 10 to 200 kg/m³ depending on the agent and polymer.^[6] The choice of blowing agent determines not only processability but also end-use properties, such as thermal conductivity, which is governed by the trapped gas's heat transfer characteristics—low-conductivity gases like hydrofluoroolefins (HFOs) enhance insulation compared to air.^[31] Blowing agents are classified into physical and chemical types based on their gas-generation mechanism. Physical blowing agents, including gases like carbon dioxide (CO₂), nitrogen (N₂), and hydrocarbons such as isobutane or pentane, are dissolved under pressure and expand upon decompression or heating due to their volatility, making them suitable for continuous processes like extrusion foaming of polystyrene or polyethylene.^[8] ^[6] Chemical blowing agents (CBAs), conversely, decompose thermally to release non-condensable gases such as nitrogen (N₂) or carbon dioxide (CO₂); common examples include azodicarbonamide (decomposing above 190°C to yield N₂, CO, and ammonia residues) and modified hydrazides, which enable precise control in batch or semi-continuous molding of rigid foams like polyurethane or epoxy.^[32] Physical agents offer advantages in scalability and recyclability at high production rates, while CBAs provide uniform gas distribution in viscous melts but may introduce decomposition byproducts affecting purity.^[33] Regulatory and environmental constraints have shaped blowing agent evolution, particularly following the 1987 Montreal Protocol, which phased out chlorofluorocarbons (CFCs) like CFC-11 (formerly used for low-k-factor rigid polyurethane foams) by 1996 in developed nations due to stratospheric ozone depletion.^[34] Subsequent shifts targeted hydrofluorocarbons (HFCs) under the 2016 Kigali Amendment, promoting low-global-warming-potential alternatives such as HFO-1234ze (GWP <1) or hydrocarbons, which maintain foam performance while reducing climate impact—HFOs, for instance, achieve comparable solubility and expansion to HFC-245fa in spray polyurethane foams.^[35] In polystyrene foams, n-pentane (introduced post-CFC ban in the 1990s) remains prevalent, with cell nucleation enhanced by its 36°C boiling point matching extrusion conditions around 200-220°C.^[6] Additives complement blowing agents by modulating foaming dynamics and foam integrity, including nucleating agents like talc or sodium bicarbonate hybrids that increase cell nucleation density (up to 10^6-10^9 sites/cm³) for finer, uniform cells and reduced skin defects in extruded foams.^[16] Surfactants, such as silicone-based polyethers, stabilize bubble interfaces during expansion, preventing coalescence in flexible polyurethane foams where water acts as a co-blowing agent via reaction with isocyanates to produce CO₂.^[8] Other additives include cell openers (e.g., polyglycols) to promote interconnected structures for acoustic absorption and fillers like nanoclays that reinforce cell walls against collapse, improving compressive strength by 20-50% in syntactic foams.^[6] Catalysts, such as tin compounds in polyurethanes, accelerate reaction rates to synchronize gas generation with polymerization, ensuring dimensional stability.^[16] These components are typically added at 0.1-5 wt% levels, with selection driven by polymer rheology and target morphology—e.g., hydrophobic additives for polyolefin foams versus hydrophilic ones for water-blown systems.^[32]

Material Properties

Mechanical and Structural Characteristics

Polymeric foams possess a cellular architecture characterized by gas-filled voids embedded in a continuous polymer matrix, resulting in relative densities (ρ*/ρ_s) typically between 0.01 and 0.3 compared to the solid polymer.^[36] This structure imparts low bulk density, often below 0.1 g/cm³ for lightweight variants, while medium- (0.1–0.5 g/cm³) and high-density (0.5–1.0 g/cm³) foams provide enhanced load-bearing capacity.^[3] Cell morphology varies between open-cell configurations, where voids interconnect to permit fluid and gas permeation, and closed-cell types, featuring isolated, impermeable cells that confer greater structural integrity and resistance to environmental ingress.^[3] Factors such as polymer type, foaming process parameters, and additives dictate cell size (often 10–500 μm), shape (spherical to elongated), and uniformity, with anisotropic morphologies arising in extrusion-based production.^[15] Mechanical performance derives primarily from the interplay of matrix material properties, relative density, and cellular geometry, as formalized in the Gibson-Ashby model for cellular solids.^[36] For open-cell foams dominated by cell-wall bending, the elastic modulus (E*) scales as E* ≈ E_s (ρ*/ρ_s)^2, where E_s is the solid polymer modulus, yielding values from 10–300 kPa in low-density polyurethane variants; closed-cell foams exhibit similar scaling but with contributions from gas pressure within cells, enhancing stiffness.^[36]^[5] Compressive strength (σ*) follows a comparable quadratic dependence on relative density, with rigid foams achieving 0.1–2 MPa before densification, while flexible foams prioritize energy absorption through progressive cell collapse during a characteristic plateau in the stress-strain curve.^[3]^[37] Deformation mechanisms under load include initial linear elasticity from cell-wall stretching or bending, followed by plastic buckling or fracture in rigid foams and viscoelastic recovery in flexible ones, with fatigue resistance improving at higher densities due to reduced strain localization.^[38] Specific strength (strength per unit density) often surpasses that of the base polymer, enabling applications in impact protection, though open-cell structures generally offer lower rigidity but superior conformability compared to closed-cell counterparts.^[6]^[39] Morphology refinements, such as uniform small cells, mitigate defects and elevate overall toughness, governed by the base polymer, processing method, and resultant foam architecture.^[40]

Thermal, Acoustic, and Chemical Behaviors

Polymeric foams exhibit low thermal conductivity due to their gas-filled cellular structure, which minimizes heat transfer through conduction, convection, and radiation across the solid polymer skeleton. Rigid polyurethane foams, a common type, typically display thermal conductivities of 0.018–0.028 W/m·K at ambient conditions, enabling superior insulation compared to materials like expanded polystyrene (0.029–0.033 W/m·K).^[41]^[42] Closed-cell variants enhance this by trapping low-conductivity gases like hydrofluoroolefins, though long-term exposure leads to gas diffusion and conductivity increases over time, potentially rising by 20–50% after years of service.^[43] Temperature elevation further impacts performance; for polyurethane foams, mechanical and thermal properties degrade above 100–150°C, with softening and increased conductivity observed due to polymer chain mobility.^[44] Acoustically, polymeric foams, particularly open-cell types like polyurethane, absorb sound via energy dissipation mechanisms including viscous friction and thermal gradients within pore walls and air channels. Sound absorption coefficients for unmodified polyurethane foams range from 0.1 at 600 Hz to 0.5 at 1600 Hz, with effectiveness improving in thicker samples or those modified with fillers, achieving values exceeding 0.9 across broader mid-to-high frequency bands (e.g., 1000–6000 Hz).^[45]^[46] Factors such as cell openness, density (lower densities favor absorption), and tortuosity influence performance; closed-cell foams provide better transmission loss for noise barriers but inferior absorption compared to open-cell counterparts.^[47] Chemical behaviors of polymeric foams depend on the base resin, additives, and cell morphology, with resistance generally mirroring that of the solid polymer but modulated by increased surface area in foams. Polyethylene foams resist dilute acids, bases, salts, and alcohols effectively up to 60°C, showing minimal swelling or degradation, but succumb to aromatic hydrocarbons (e.g., benzene, toluene) and strong oxidants, which promote stress cracking or permeation.^[48]^[49] Polyurethane foams offer good to excellent tolerance for water, aliphatic hydrocarbons, and mineral oils but fair to poor resistance against ketones, esters, and concentrated acids, often resulting in hydrolysis, swelling, or structural breakdown upon prolonged contact.^[50] Higher-density or cross-linked foams exhibit enhanced durability, though environmental factors like temperature accelerate chemical attack across types.^[51]

Primary Applications

Building and Insulation Uses

Polymeric foams, particularly rigid polyurethane (PUR), polyisocyanurate (PIR), expanded polystyrene (EPS), and extruded polystyrene (XPS), serve as key thermal insulation materials in building construction, offering low thermal conductivity values typically ranging from 0.02 to 0.04 W/m·K, which translate to R-values of 5 to 7 per inch for standard formulations.^[52]^[53] These properties enable effective reduction in heat transfer, with closed-cell PUR foams achieving densities of 30–45 kg/m³ and providing superior resistance to moisture ingress compared to open-cell variants. In walls, roofs, and floors, these foams are applied as rigid boards, spray-in-place systems, or foam-in-place injections to minimize energy loss, contributing to compliance with building energy codes that mandate minimum insulation levels, such as R-30 for attics in many U.S. residential standards.^[54] EPS and XPS boards are commonly installed in foundation perimeters, under concrete slabs, and as continuous exterior insulation to prevent thermal bridging, with EPS exhibiting compressive strengths up to 15–30 psi suitable for load-bearing applications like insulated concrete forms (ICFs).^[55] The global EPS market for building and construction reached approximately 4.8 billion USD in 2024, driven by demand for lightweight, cost-effective insulation that enhances structural efficiency without adding significant dead load.^[56] Spray polyurethane foam (SPF), applied via on-site expansion, fills irregular voids in attics, rim joists, and crawl spaces, achieving air leakage reductions of up to 80% in retrofitted buildings, thereby improving overall envelope performance.^[57] In commercial and residential roofs, PIR boards with facers provide high R-values per inch (up to R-6.5) and dimensional stability under temperature fluctuations from -20°C to 80°C, supporting flat or low-slope designs where weight savings are critical.^[58] Lifecycle analyses indicate that PUR insulation in buildings yields an energy payback within 3–6 months, saving up to 70 times the energy invested in its production over a 50-year service life, primarily through reduced heating and cooling demands.^[59] Acoustic benefits, such as sound transmission class (STC) ratings of 45–50 for foam-layered walls, further extend their utility in multi-family dwellings.^[60] However, installations must adhere to fire codes requiring flame spread indices below 75 and smoke development under 450 per ASTM E84, often necessitating thermal barriers like gypsum board unless tested assemblies permit direct exposure.^[61]

Industrial and Transportation Roles

Polymeric foams, particularly rigid polyurethane variants, are employed in industrial manufacturing for thermal insulation in equipment such as refrigeration units and high-temperature processing machinery, leveraging their low thermal conductivity values often below 0.03 W/m·K to minimize heat loss and enhance energy efficiency.^[62] Flexible foams contribute to vibration damping and noise reduction in machinery housings, while expanded polypropylene (EPP) and polystyrene/polyamide (PS/PA) foams provide energy absorption through mechanisms like cell buckling and fracture, protecting components during mechanical stresses.^[63] These properties support applications in protective padding for tools and safety barriers, where high specific strength and corrosion resistance extend equipment lifespan.^[6] In transportation sectors, flexible polyurethane foams dominate automotive interiors, forming seats, headrests, and armrests that offer cushioning and impact energy dissipation, with a single modern vehicle typically incorporating dozens of such components to reduce weight by up to 20-30% compared to alternatives, thereby improving fuel economy.^[64] The global polyurethane-based foams market in automotive applications reached USD 13.33 billion in 2024, driven by demand for lightweighting in electric vehicles and compliance with crash safety standards, where foams absorb kinetic energy via progressive cell collapse.^[65] ^[66] Similar foams extend to trucks, buses, trains, and marine vessels for seating and insulation, while in aerospace, specialized foams enable structural lightweighting in interiors and panels, supporting a market valued at USD 6.81 billion in 2024 with projections to USD 11.06 billion by 2032 due to performance demands in fuel-efficient aircraft designs.^[67]

Everyday Consumer and Packaging Functions

Polymeric foams serve critical roles in everyday consumer products and packaging due to their lightweight nature, shock absorption, and thermal insulation properties. Expanded polystyrene (EPS) foam is commonly employed in protective packaging for fragile items such as electronics and appliances, where its low density—typically around 15-30 kg/m³—minimizes shipping weight while providing superior cushioning against impacts.^[68] In food packaging, EPS forms trays for meat, fish, fruits, and vegetables, extending shelf life through insulation that maintains temperatures and reduces spoilage; for instance, it is used in egg cartons to prevent breakage during transport.^[69] Polyethylene (PE) foams, often in closed-cell structures, protect sensitive consumer goods like glassware and ceramics in e-commerce shipments, offering durability and resistance to moisture without adding significant weight.^[70] In consumer goods, flexible polyurethane foams dominate applications requiring cushioning and comfort. These foams, with densities ranging from 16-48 kg/m³, fill sofa cushions, mattresses, and bedding, providing resilient support that conforms to body weight while returning to shape after compression.^[71] Polyurethane is also integral to furniture upholstery and carpet underlays, enhancing durability and noise reduction in household settings.^[71] Additionally, PE foams appear in everyday items like flotation devices and sports equipment, leveraging their buoyancy and flexibility for safety and performance.^[72] These applications highlight polymeric foams' efficiency in reducing material use compared to alternatives like solid plastics, as foams achieve similar protective functions with 90-98% air content, lowering costs and environmental footprint in production.^[73] However, their effectiveness depends on precise density and cell structure selection to match specific impact energies, ensuring minimal product damage in transit.^[74]

Performance Advantages

Efficiency and Economic Benefits

Polymeric foams enhance energy efficiency primarily through their superior thermal insulation properties, which minimize heat transfer in building envelopes and reduce the demand for heating and cooling systems. For instance, polyurethane foams exhibit low thermal conductivity, often below 0.03 W/m·K, enabling significant reductions in energy consumption for climate control in structures.^[3] This efficiency contributes to lower operational costs, with studies indicating that foam insulation can decrease building energy use by up to 50% compared to uninsulated alternatives, thereby supporting broader efforts to improve overall system performance without excessive material volume.^[53] In transportation applications, the low density of polymeric foams—typically ranging from 10 to 100 kg/m³—allows for substantial weight reductions in vehicles, directly improving fuel economy. A 10% decrease in vehicle mass, achievable through foam integration in components like seats and panels, correlates with 6-8% better fuel efficiency, translating to measurable savings in operational fuel costs over a vehicle's lifecycle.^[75] ^[76] This lightweight advantage extends to logistics, where foams in packaging reduce shipping weights, lowering transportation energy requirements and associated expenses. Economically, polymeric foams offer cost-effectiveness due to their high performance-to-weight ratio and simplified processing, which streamline manufacturing and assembly. In construction, expanded polystyrene (EPS) foam blocks can cut overall project expenses by 20-25% relative to traditional materials by accelerating installation and diminishing the need for additional structural supports or energy-intensive HVAC systems.^[77] Polyurethane foam panels further reduce long-term costs through minimized maintenance and energy bills, with return on investment often realized within 2-5 years via insulation-driven savings.^[78] In packaging, their durability and impact absorption enable reusable designs, decreasing replacement frequency and material waste, while low raw material costs—stemming from efficient foaming processes—keep production economical at scale.^[79]

Versatility in Engineering Solutions

Polymeric foams exhibit versatility in engineering solutions through their ability to combine low density—often ranging from 10 to 200 kg/m³—with high specific strength and customizable microstructures, enabling tailored responses to mechanical, thermal, and acoustic demands across industries.^[6] This adaptability arises from fabrication techniques such as extrusion, injection molding, and supercritical foaming, which allow precise control over cell size, morphology, and additives to optimize properties like energy absorption and stiffness.^[3] In structural engineering, rigid polyurethane foams reinforce composite sandwich panels used in aerospace and automotive components, providing up to 70% weight reduction compared to solid polymers while maintaining compressive strengths exceeding 1 MPa.^[80] In automotive engineering, expanded polypropylene (EPP) foams serve as impact-absorbing elements in bumpers and side panels, dissipating crash energies through progressive deformation and reducing occupant injury risks by factors of 2-3 in low-speed collisions, as demonstrated in standardized tests.^[81] Similarly, in civil engineering, syntactic foams—incorporating hollow microspheres—enhance buoyancy and corrosion resistance in offshore platforms and subsea pipelines, with buoyancy moduli up to 0.8 enabling stable flotation under hydrostatic pressures of 10-20 MPa.^[82] These foams' damping coefficients, often 0.1-0.5, also mitigate vibrations in machinery mounts and rail systems, extending equipment lifespan by minimizing fatigue failures.^[74] Biomedical engineering leverages the open-cell structures of polylactic acid (PLA) foams for tissue scaffolds, where pore sizes of 100-500 µm promote cell infiltration and vascularization, supporting bone regeneration rates 20-30% higher than non-porous alternatives in vitro studies.^[83] In energy systems, conductive polymer foams integrated with carbon nanotubes form lightweight electrodes for supercapacitors, achieving specific capacitances over 200 F/g due to high surface areas exceeding 100 m²/g.^[84] This multifunctionality stems from the foams' capacity to integrate additives like nanoparticles, yielding hybrid materials that address concurrent challenges such as weight, durability, and functionality without compromising performance.^[16]

Key Challenges and Criticisms

Fire Safety and Combustion Risks

Polymeric foams, particularly polyurethane and polystyrene variants, exhibit high flammability due to their organic composition and cellular structure, which facilitates rapid heat transfer and oxygen access during ignition. Flexible polyurethane foams used in furniture and bedding typically have a limiting oxygen index (LOI) of around 18-20%, rendering them susceptible to sustained combustion once ignited, with peak heat release rates exceeding 200 kW/m² in bench-scale tests.^[85] Expanded polystyrene (EPS) foams, common in insulation and packaging, similarly propagate flames quickly, often melting and dripping to spread fire to underlying surfaces.^[86] These properties contribute to accelerated fire growth in enclosed spaces, as demonstrated in medium-scale tests where upholstered chairs with polyurethane cushions fully combust within 6 minutes of ignition.^[87] Combustion of polymeric foams generates dense smoke and toxic effluents that pose acute hazards beyond thermal exposure. Polyurethane decomposition yields high concentrations of carbon monoxide (CO), hydrogen cyanide (HCN), and isocyanates, which impair visibility, induce respiratory distress, and cause rapid incapacitation; HCN levels can reach lethal thresholds (e.g., 100 ppm) within minutes in under-ventilated conditions.^[88] Polystyrene combustion releases styrene monomer, benzene, and soot-laden smoke, exacerbating inhalation risks and contributing to post-fire toxicity.^[86] Overall, fire incidents involving these materials have been linked to over 40,000 global deaths annually, underscoring their role in enhancing fire severity through smoke obscuration and gas production.^[89] Fire retardants, such as phosphorus-based compounds or reactive melamine polyphosphates, are incorporated to mitigate risks by promoting char formation and reducing heat release, achieving UL-94 V-0 ratings in some rigid polyurethane formulations with as little as 6 wt.% additive.^[90] However, effectiveness varies; additive retardants may leach over time or fail under real-fire conditions, while halogenated variants, though efficient in gas-phase radical scavenging, can evolve additional toxic halogens during pyrolysis.^[91] National standards, like those tested by NIST, reveal that even treated foams retain ignition propensity, necessitating complementary barriers or intumescent coatings for substantial risk reduction.^[92] Persistent challenges include trade-offs between retardancy and foam integrity, as high loadings degrade mechanical properties without fully eliminating smoldering or piloted ignition pathways.^[88]

Toxicity and Health Concerns

Polymeric foams, particularly polyurethane and polystyrene variants, pose health risks primarily through residual monomers, additives, and volatile emissions. Isocyanates, key precursors in polyurethane foam production, are highly reactive chemicals that can cause acute irritation to the eyes, skin, and respiratory tract upon exposure, with chronic inhalation leading to occupational asthma in up to 5-10% of exposed workers according to occupational health data.^[93] ^[94] Toluene diisocyanate (TDI), a common isocyanate, is rated among the most toxic due to its potential to sensitize airways and exacerbate pulmonary function decline over repeated low-level exposures.^[95] In finished products like furniture and insulation, unreacted isocyanates may persist at trace levels, contributing to off-gassing of volatile organic compounds (VOCs) that degrade indoor air quality. Studies indicate polyurethane foams emit VOCs such as formaldehyde and amines, which can irritate mucous membranes and contribute to symptoms of sick building syndrome, including headaches and throat discomfort, though emission rates typically decline after initial curing periods of days to weeks.^[96] ^[97] Polystyrene foams, including expanded polystyrene (EPS), release styrene monomer, classified as a probable human carcinogen by the International Agency for Research on Cancer, with occupational exposure linked to increased leukemia risk and neurobehavioral deficits in cohort studies of manufacturing workers.^[98] Consumer risks from EPS packaging or food containers arise mainly from styrene leaching when heated, potentially contaminating food and causing endocrine disruption at doses above 90 mg/kg body weight in animal models.^[99] Flame retardants added to polyurethane foams for compliance with standards like California's TB 117, such as polybrominated diphenyl ethers (PBDEs), exhibit bioaccumulative properties and are associated with neurodevelopmental impairments, reduced fertility, and thyroid hormone interference in epidemiological studies of exposed populations.^[100] ^[101] These organohalogen compounds can migrate from foam in household dust, with detectable levels in 80-90% of U.S. home environments correlating to higher blood PBDE concentrations in children and adults.^[102] While regulatory phase-outs of certain PBDEs since 2004 have reduced some exposures, replacement retardants like chlorinated phosphates lack comprehensive long-term toxicity data, prompting concerns over persistent substitution risks.^[103] Spray-applied polyurethane foams amplify risks during installation, where improper curing has led to documented cases of chemical pneumonitis and dermal burns from isocyanate overexposure.^[104] Overall, while cured foams are generally inert under normal use, vulnerabilities during manufacturing, application, and degradation underscore the need for ventilation controls and material certifications to mitigate inhalation and dermal pathways.^[105]

Environmental Persistence and Disposal Issues

Polymeric foams, particularly expanded polystyrene (EPS) and polyurethane (PU), exhibit high environmental persistence due to their chemical stability and resistance to biodegradation. EPS foam, commonly used in packaging, fragments into microplastics under mechanical stress, UV exposure, or wave action rather than fully degrading, persisting in marine and terrestrial environments for decades and entering food chains via ingestion by organisms.^[106]^[107] PU foams demonstrate similarly low biodegradability, with studies showing only partial mineralization of soft segments (up to 77% after six months in soil) while the overall structure remains recalcitrant, contributing to long-term accumulation as non-degradable debris.^[108]^[109] Disposal of polymeric foams poses significant challenges, primarily stemming from their low density and bulkiness, which increase transportation costs and limit recycling infrastructure. EPS recycling rates remain low—often below 10% in many regions—due to contamination, lack of collection programs, and economic infeasibility, leading most waste to landfills where it occupies disproportionate volume without significant decomposition.^[110] PU foams face analogous issues, with mechanical recycling hindered by heterogeneity and chemical recycling requiring energy-intensive processes that yield lower-value products.^[111] Incineration, an alternative for energy recovery, risks releasing toxic emissions including carbon monoxide, hydrogen cyanide, and nitrogen oxides from PU, exacerbating air pollution concerns.^[111] These persistence and disposal problems have prompted regulatory actions, such as bans on single-use EPS in jurisdictions like Washington State since 2022, citing its role in persistent litter and microplastic generation over recyclability benefits. Landfilling further contributes to greenhouse gas emissions from slow anaerobic degradation, underscoring the need for improved waste management without relying on unproven biodegradation claims for conventional foams.^[112]^[113]

Recent Advancements

Bio-Based and Sustainable Formulations

Bio-based polymeric foams utilize renewable feedstocks such as vegetable oils, lignin, starch, and polysaccharides to partially or fully replace petroleum-derived precursors, thereby reducing dependence on non-renewable resources and mitigating greenhouse gas emissions associated with fossil fuel extraction and processing.^[114] These formulations prioritize sustainability through lower carbon footprints, with life-cycle analyses indicating up to 50% reductions in global warming potential for bio-polyurethane (PU) variants compared to conventional counterparts, depending on bio-content levels.^[115] Common synthesis involves converting biomass into polyols or monomers via epoxidation, hydroformylation, or fermentation, followed by polymerization with isocyanates or non-isocyanate routes to form cellular structures.^[116] Bio-polyurethane foams dominate this category, derived from bio-polyols sourced from soybean oil, castor oil, or lignin, achieving bio-contents of 20-100% while retaining densities of 20-60 kg/m³ and compressive strengths comparable to petroleum-based PU (0.1-0.5 MPa for flexible foams).^[114] For instance, rigid bio-PU foams from apricot stone shell polyols exhibit thermal conductivities as low as 0.025 W/m·K, suitable for insulation, with enhanced flame retardancy due to inherent char-forming biomass components.^[117] Flexible bio-PU from succinic acid-based polyols demonstrates elastic moduli up to 1.5 MPa and improved recyclability via glycolysis, addressing end-of-life disposal challenges.^[118] Other variants include polylactic acid (PLA) foams from corn starch, offering biodegradability under industrial composting (disintegration in 90 days at 58°C) but with lower mechanical toughness (tensile strength ~10 MPa) than polystyrene foams.^[115] Polyhydroxyalkanoate (PHA) and cellulose-based foams provide inherent biodegradability in soil (degradation rates of 50-80% within 6 months) and high water resistance, though scalability remains limited by production costs exceeding $4/kg.^[119] Sustainability extends to reduced toxicity, as bio-formulations often eliminate volatile organic compounds from petrochemical blowing agents, favoring water or CO₂ alternatives that lower ozone depletion potential.^[120] Recent advancements include pine-derived polyols for PU foams, developed in 2025, which substitute fossil polyethers while maintaining foam expansion ratios of 30-50 times and enabling enzymatic degradation.^[121] Hybrid biofoams incorporating nanofillers like cellulose nanocrystals enhance mechanical properties (e.g., 20-30% increase in modulus) without compromising renewability.^[122] However, challenges persist, including higher viscosity of bio-polyols leading to inconsistent cell morphology and production costs 1.5-2 times those of synthetic foams, necessitating process optimizations like microwave-assisted synthesis for viability.^[123] Applications span thermal insulation in buildings (bio-PU panels with R-values >5 m²·K/W), automotive seating, and packaging, where biodegradability supports circular economy goals, though full commercialization requires overcoming supply chain variability in biomass feedstocks.^[116]

Enhanced Formulations with Nanomaterials

The incorporation of nanomaterials such as carbon nanotubes (CNTs), graphene nanosheets (GNPs), and nanoclays into polymeric foams, particularly polyurethane (PU) variants, enables precise control over cellular morphology and matrix reinforcement at the nanoscale, leading to superior mechanical integrity without substantially increasing density.^[124] ^[125] For instance, rigid PU foams reinforced with 0.5-2 wt% GNPs exhibit up to 50% higher compressive strength and Young's modulus compared to neat PU foams, attributed to the high aspect ratio and interfacial bonding of GNPs that distribute stress more evenly across the foam structure.^[125] Similarly, multi-walled CNTs at 1 wt% in PU foams increase compressive modulus by 20-30% while acting as nucleation sites to refine cell size and boost cell density, thereby enhancing load-bearing capacity.^[126] ^[127] Nanoclays, such as montmorillonite, further augment these formulations by promoting heterogeneous nucleation during foaming, resulting in smaller, more uniform cells that improve both mechanical toughness and thermal insulation. In flexible PU foams, additions of 1-3 wt% nanoclay elevate sound absorption coefficients by 15-25% across mid-frequency ranges due to increased viscous dissipation in refined pore walls.^[128] ^[129] Graphene and CNT hybrids yield multifunctional outcomes, including electromagnetic interference (EMI) shielding effectiveness exceeding 40 dB at 1 wt% loading in PU matrices, alongside flame retardancy improvements via char formation that reduces peak heat release rates by up to 30%.^[130] ^[131] These enhancements stem from the nanomaterials' ability to bridge polymer chains and inhibit crack propagation, though uniform dispersion remains critical to avoid agglomeration-induced weak points.^[132] Recent developments as of 2023 emphasize hybrid nanocomposites for specific applications, such as PMMA-based nanocellular foams with silica nanoparticles, which achieve thermal conductivities below 30 mW/m·K—comparable to aerogels—while maintaining compressive strengths over 1 MPa at densities under 100 kg/m³.^[133] In bio-oriented foams, CNTs combined with graphene oxide improve biodegradability alongside mechanical uplift, with tensile strengths rising 40% in starch-PU blends processed via supercritical CO₂ foaming.^[134] Challenges include potential cytotoxicity from nanoparticle leaching, necessitating surface functionalization, and scalability issues in melt-processing, where shear-induced alignment can unevenly affect isotropy.^[3] Overall, these formulations expand polymeric foams' viability in aerospace, automotive, and insulation sectors by balancing lightweight design with durability.^[127]

References

[1]
Polyurethane Foams: Past, Present, and Future - PMC
1. Polymeric Foams. Materials such as plastic foams, foamed plastics, cellular plastics, or polymeric foams are materials that consist of a solid phase and a ...
[2]
Polymeric Foam - an overview | ScienceDirect Topics
Polymeric foams are low-density materials that serve as key components in lightweight structures for construction and transportation, providing functionalities ...
[3]
Introduction to Polymeric Foams | ACS Symposium Series
Jun 8, 2023 · Their uses include the manufacture of materials for thermal and sound insulation, packing, footwear, furniture, household, and construction, ...
[4]
Types of Polymeric Foams | ACS Symposium Series
Jun 8, 2023 · There are two kinds of urethane foams: flexible foams and rigid foams. All things considered, flexible foams can be further subdivided into ...Types of Foams · Thermoplastic Foam · Thermoset Foams · Speciality Foams
[5]
Polymer foams as advanced energy absorbing materials for sports ...
Oct 9, 2021 · Foamed polymer products have numerous advantageous properties, including low density, good heat and sound insulation, and excellent energy ...
[6]
Recent Trends of Foaming in Polymer Processing: A Review - PMC
Polymer foams have low density, good heat insulation, good sound insulation effects, high specific strength, and high corrosion resistance.
[7]
Recent progress in functional applications of polymer foams
This review summarizes the potential drawbacks and possible solutions for polymer foams in functionalized applications, as well as reflections on their future ...
[8]
[PDF] POLYMER FOAMS
Polymer foams can be divided into either thermoplastics or thermosets, which are further divided into rigid or flexible foams.
[9]
Density Gradients, Cellular Structure and Thermal Conductivity of ...
Sep 29, 2022 · Polymer foams can be defined as two-phase materials in which a gas is dispersed in a continuous macromolecular phase [1]. Polymer foams are ...<|separator|>
[10]
[PDF] 1 Introduction - 1.1 Overview of Polymer Foams - Wiley-VCH
Polymer foams are defined as a kind of polymer material formed by a large number of microcellular cells containing a gas medium uniformly dispersed in the ...
[11]
Deformation and Simulation of the Cellular Structure of Foamed ...
Nov 24, 2022 · Polymer microcellular-foamed plastics are polymer foam materials with cell diameter between 0.1 and 10 μm, and cell densities greater than ...
[12]
Polymeric Foams - PMC
Jul 12, 2019 · This is the case of polymeric foams, which may display good structural properties alongside functional characteristics through complex ...
[13]
Foams | California Air Resources Board - CA.gov
“Polystyrene Extruded Boardstock and Billet (XPS)” means a foam formed from polymers of styrene and produced on extruding machines in the form of foam slabs ...Missing: definition | Show results with:definition
[14]
Structural characterization of hierarchical polymer foams by ...
In this paper, the various cells of a polymer foam are defined according to their size: <1 μm (nanocells), 1–100 μm (microcells), and >100 μm (macrocells). 3.
[15]
A comprehensive review of cell structure variation and general rules ...
Feb 15, 2022 · ... cell structure variation would be obtained. The total volume of polymer foam consists of the volume of the cell wall and the struts and that ...
[16]
Polymeric Foaming - Mechanism, Types of foams & Applications
Jul 22, 2024 · Polymeric Foams and Their Applications · Polystyrene foam. Polystyrene is an amorphous polymer used to make foam by extrusion, injection, and ...
[17]
Fundamentals of Polymeric Foams and Classification of Foam Types
In this paper, the classification of polymer foams, principles of the foaming process, types of blowing agents, and raw materials of polymer foams are reviewed.<|separator|>
[18]
[PDF] POLYMERIC FOAMS - download.polympart.ir
One of the main objectives of this volume is to provide a clear understanding of the fundamental mechanisms and material characteristics of polymeric foam.
[19]
Otto Bayer and the History of Polyurethane - ThoughtCo
Mar 17, 2017 · Polyurethane is an organic polymer, discovered by Otto Bayer and co-workers in 1937, and named by Heinrich Rinke. It is used in foams, coatings ...
[20]
History of Polyurethane Foam Development - Elastas
Polyurethane was first synthesized in 1937. Foam development began in the 1950s, with flexible foam introduced in 1954, and polyether polyols in the late 1950s.
[21]
History of polyurethane - Imenpol blog
Sep 22, 2024 · The 1953, the first commercial production of polyurethane foam began in the US. which was a rigid foam and used for insulation and three ...<|separator|>
[22]
https://www.foambymail.com/blog/foam-manufacturing-development-and-competition-through-history/
[23]
Polystyrene Accident Sparked Plastic Evolution - Plastics Today
Sep 11, 2025 · In the 1940s, Ray McIntire, a Dow scientist, accidentally invented foamed polystyrene (which would become Styrofoam) while searching for a ...
[24]
The History of Plastics Part II from 1935- 1980 by Advanced Plastiform
The industry experienced over 15 percent growth between 1946 and 1960 and by 1960, plastic had surpassed aluminum in production.
[25]
Polyurethane Foams History and Current Use - RhinoLift Foundation
Apr 29, 2024 · After the war, polyurethane foam was quickly adopted by the manufacturing industry due to its versatility and cost-effectiveness. It was used in ...
[26]
Flexible Polyurethane Foam Hall of Fame
The timeline for Union Carbide innovations spanned the period from the early 1950s through 1993 when the last vestiges of the business were sold. An ...Missing: 1940s | Show results with:1940s<|separator|>
[27]
https://www.rpll.co.uk/the-history-of-foam-and-its-evolution-in-different-industries/
[28]
A brief history of Spray foam... - WRI Applications, LLC
Aug 24, 2011 · First foam made in 1939, military used in 1940s, first roof in 1957, first machine in 1963, 70s saw fire concerns, 2000s saw big growth.Missing: commercialization 1950s
[29]
Foaming Technology | ACS Symposium Series
Jun 8, 2023 · The two primary techniques for processing polymer foam are foam extrusion molding but also foam injection molding. The foam molding processes ...Foaming Methods · Foaming Techniques · Challenges in Polymeric Foam...
[30]
Blowing Agent - an overview | ScienceDirect Topics
The function of a blowing agent is to generate a gas during melt processing and thereby to expand the polymer into a cellular structure or foam. Agents are ...
[31]
Chapter 2: Blowing Agents - GlobalSpec
The blowing agent plays a very important role in both the manufacturing and performance of polymer foam. The blowing agent is the dominant factor controlling ...
[32]
Blowing agents – Knowledge and References - Taylor & Francis
Chemical blowing agents are mixed into the polymer and decompose into gases, often nitrogen or carbon dioxide, when the processing temperature reaches the ...<|separator|>
[33]
Chemical vs Physical Foaming - Trexel Inc.
In general, physical foaming is more cost effective at high machine utilization rates and chemical foaming at low machine utilization rates.
[34]
[PDF] Foamed Plastics - FAA Fire Safety
In many cases a combination of water and volatile blowing agents is used. In rigid foams, fluorocarbon 11 is primarily used because of the low. K factor it ...
[35]
[PDF] Assessment of the Performance of Hydrofluoroolefins ... - INFO
Hydrochlorofluoroolefins and hydrofluoroolefins are well established foam blowing agents (FBA) in. High-Pressure Spray Foam (HP-SPF) applications due to the ...
[36]
The mechanical properties of cellular solids
The mechanical properties (elastic, plastic, creep, and fracture) of cellular solids or foams are related to the properties of the cell wall material and to ...
[37]
Compressive behavior and deformation mechanisms of rigid ...
Mar 15, 2023 · Polymeric foams might undergo large deformation at high loading rates in their application in the transportation industry. Therefore, securing a ...
[38]
Mechanical Fatigue of Polymer Foams - A Review
This literature review further presents a broad overview of the information available to understand the relations between loading conditions and fatigue ...
[39]
Foam Cell - an overview | ScienceDirect Topics
In the closed cell foam, each cell is an independent closed entity. The cells resemble small glass bubbles that have been dispersed in the polymer. The walls of ...
[40]
(PDF) Polymeric Foams: Mechanisms and Properties - ResearchGate
Jul 2, 2023 · Polymeric foams are a type of lightweight materials that are used for screening assets against mechanical injuries like shock and vibration.
[41]
What is Rigid Polyurethane Foam? What are the Application Areas?
Jul 22, 2024 · Rigid polyurethane foam provides high thermal insulation with low thermal conductivity (0.018-0.024 W/m-K). This helps to reduce both heating ...
[42]
What is the thermal conductivity of polyurethane?
Extruded polystyrene. 0.029-0.033 W/mK ; Polyurethane systems. 0.022-0.028 W/mK ; Mineral wool. 0.031-0.045 W/mK ; Expanded Perlite. 0.040-0.060 W/mK ; Wood chips.
[43]
Polyurethane Foams for Thermal Insulation Uses Produced ... - NIH
Typical thermal conductivity values for polyurethane foams are between 0.02 and 0.03 W ... thermal conductivity of 0.021–0.029 W·mK−1. However, the reactions to ...
[44]
A Review of Research on the Effect of Temperature on the ... - MDPI
Oct 28, 2022 · Temperature is one of the main factors affecting the properties of polyurethane foams, and there are large differences in the mechanical ...
[45]
Absorption coefficient of polyurethane foam. - ResearchGate
... PU foam has sound absorption value in the lowfrequency and middle-frequency ranges of 0.116 at 600 Hz and 0.506 at 1600 Hz, respectively. The same ...
[46]
Acoustic properties of polymer foam composites blended with ...
This study investigates the acoustic properties of polymer foam composites (FC) filled with natural fiber. The FC were produced based on crosslinking of ...
[47]
Thermal Insulation and Sound Absorption Properties of Open-Cell ...
Dec 12, 2020 · The main goal of this work was to evaluate the thermal insulation and sound absorption properties of open-cell rigid polyurethane foams
[48]
[PDF] Polyethylene chemical resistance - Braskem
Polyethylene has high resistance to aqueous solutions of salts, acids, and alkalis, and many solvents up to 600C, but not to strong oxidizing agents.
[49]
https://www.calpaclab.com/chemical-charts/
[50]
[PDF] Chemical Resistance of Polyurethane Foams
Code: E= Excellent, G=Good resistance, F=Fair resistance, P=Poor resistance, S=Severe solvent action or chemical attack, not recommended for use.
[51]
[PDF] Chemical Resistance of EPE/EPP Foam
These materials are resistant to a broad spectrum of solvents and chemicals. The data presented here was supplied by our base resin material supplier and refers ...
[52]
[PDF] Thermal insulation materials made of rigid polyurethane foam
Oct 6, 2015 · The density of rigid polyurethane foam (PUR/PIR) used for thermal insulation in buildings normally ranges between 30 kg/m³ and 45 kg/m³. ...
[53]
Developing Insulating Polymeric Foams: Strategies and Research ...
Branching polymers have been reported to have better foaming properties, as branches contribute to melt strain hardening as they prevent the macromolecules to ...
[54]
[PDF] Polyurethane insulation for energy efficient, green buildings
Up to 1.5 billion pounds of rigid foam is used each year to reduce energy usage in construction applications e.g. residential and commercial roofs, walls, ...
[55]
Expanded Polystyrene (EPS) Market Size & Share Analysis
Sep 29, 2025 · The expanded polystyrene market size is estimated at 12.84 million tons in 2025, and is expected to reach 14.92 million tons by 2030, at a CAGR of 3.05% during ...Missing: XPS | Show results with:XPS
[56]
Building And Construction Expanded Polystyrene (EPS) Market
Rating 5.0 (40) Building and Construction Expanded Polystyrene (EPS) Market size was valued at $4.8 Bn in 2024 and is projected to reach $7.5 Bn by 2032, at a CAGR of 5.5%
[57]
As Building Energy Codes Become More Efficient, Spray Foam ...
Feb 7, 2017 · Spray polyurethane foam (SPF) insulation has been an important energy efficiency tool for decades, with specifiers, architects and builders ...<|separator|>
[58]
Sustainability: Benefits of Polyurethane and Polyiso Insulation
Energy efficient buildings, such as those using polyurethane and polyiso foam products, use less energy to heat and cool, requiring less fossil fuel use and ...
[59]
Convincing arguments for PU insulation - Covestro Solution Center
Outstanding energy balance: From a lifecycle perspective PU has an excellent energy balance. PU used in building insulation, for example, saves approximately 70 ...
[60]
Thermal Insulation Materials | Foam by Polymer Technologies
It possesses excellent thermal and acoustical insulation properties. ... R-Value of 7.55 up to 10.74, depending on installation; Emissivity Value of ...
[61]
[PDF] Meeting the Fire Code with Continuous Foam Plastic Insulation
The 2012 IBC requires foam plastic to have flame spread under 75, smoke developed under 450, and exterior walls under 25. Thermal barrier is needed unless ...
[62]
[PDF] A New Generation of Building Insulation by Foaming Polymer Blend ...
Mar 30, 2016 · We anticipate this type of polymer-clay composite can also be foamed into insulation with enhanced R-per-inch value and improved fire ...
[63]
Characterization of polymeric structural foams under compressive ...
Polymeric foams (EPP, PUR, PS/PA) were characterized using energy-absorption diagrams, showing they absorb energy through cell bending, buckling, or fracture. ...
[64]
Transportation Case Study - Polyurethane Foam Association
A modern automobile can easily have dozens of flexible polyurethane foam parts. Foam is also widely used in trucks, busses, aircraft, trains, and boats.
[65]
Polyurethane-Based Foams in Automotive Market Size & Outlook ...
The global polyurethane-based foams in automotive market size was valued at USD 13.33 billion in 2024 and is expected to grow from USD 14.08 billion in 2025 to ...
[66]
Polyurethane Foam in Aerospace and Automotive Lightweighting
Nov 15, 2018 · This article discusses three important lightweighting methods, as well as practical applications of lightweighting for the automotive and aerospace industries.
[67]
Aerospace Foam Market Size, Share & Growth | Forecast [2032]
The global aerospace foam market size was valued at USD 6.81 billion in 2024. The market is projected to grow from USD 7.21 billion in 2025 to USD 11.06 ...
[68]
Expanded Polystyrene (EPS Foam): Uses, Structure & Properties
Jul 8, 2025 · It provides cost-effective solutions and energy-efficient insulation. It also acts as a cushion transport packaging material for shock-sensitive ...
[69]
EPS Protects our Daily Life - Eumeps Corporate
With its superb insulation and shock-absorbing qualities, EPS packaging is widely used to keep fish, meat, fruit and vegetables fresh longer and protect them ...
[70]
Everything You Need to Know About PE Foam Bags: The Ultimate ...
E-commerce & Retail: Provides secure packaging for fragile consumer goods such as glassware, ceramics, and collectibles. Industrial & Manufacturing: Used for ...
[71]
Polyurethane Applications - American Chemistry Council
Flexible polyurethane foam is used as cushioning for a variety of consumer and commercial products, including bedding, furniture, automotive interiors, carpet ...
[72]
North America Polymer Foam Market Key Insights Factors for the ...
Sep 2, 2025 · ... application of polymer foams in consumer goods, sports, and leisure equipment. From yoga mats and helmets to footwear and flotation devices ...
[73]
Foam Follows Function for Efficient Ecommerce Packaging
Sep 7, 2021 · A well-designed polymer foam solution can reduce the amount of packaging required to protect a product and usually also weighs significantly ...
[74]
Applications of Polymeric Foams (Volume 2) - ACS Publications
Jun 8, 2023 · Especially, the use of polymer-based foam materials, which can provide performances such as high impact resistance, toughness, thermal stability ...<|control11|><|separator|>
[75]
Lightweight Materials for Cars and Trucks - Department of Energy
Lightweight materials offer great potential for increasing vehicle efficiency. A 10% reduction in vehicle weight can result in a 6%-8% fuel economy improvement.Missing: foams | Show results with:foams<|control11|><|separator|>
[76]
Polymeric Foams Market Size, Share & Forecast Report, 2032
In the automotive sector, a continuous emphasis on lightweight materials for enhanced fuel efficiency propels the use of polymeric foams in various components, ...
[77]
5 Cost-Saving Benefits of Foam Insulation Blocks
Mar 12, 2020 · Using EPS foam products typically reduces your overall project cost by an impressive 20 to 25% or more compared to other traditional construction materials.<|separator|>
[78]
Polyurethane Products: Helping Enable a Sustainable, Energy ...
Nov 20, 2023 · Polyurethanes can help decrease energy costs by tightening up the building envelope and have been designed to work with cleaner energy alternatives.
[79]
Benefits of Polyethylene Foam - SmartShield Packaging
Polyethylene foam is a popular packaging material because of its high strength and tear resistance, it has the ability to absorb impacts and return to form ...
[80]
Polymeric Foams - MDPI
Jul 12, 2019 · This is the case of polymeric foams, which may display good structural properties alongside functional characteristics through complex ...Missing: versatility | Show results with:versatility
[81]
Production and Application of Polymer Foams Employing ...
Dec 28, 2022 · Other foaming methods, such as injection mold, require more attention due to the mold and different shear forces involved with the process.
[82]
Recent progress in surface engineering methods and advanced ...
Owing to their porous three-dimensional (3D) interconnected structure, polymeric foams possess unique properties. They are light weight, flexible, compressible, ...
[83]
A Novel Versatile Process for the Production of Polymer Foams
Feb 15, 2011 · Polymer foam with such characteristics have great utility in tissue engineering applications. We have successfully explored polymer foams of ...
[84]
Polymer Foams for Energy Applications: Storage, Harvesting ...
Oct 19, 2025 · The ability of polymer foams to absorb and dissipate mechanical energy makes them invaluable in applications requiring impact resistance, ...
[85]
Thermal and Flammability Analysis of Polyurethane Foams ... - NIH
RPUFs are highly flammable materials with a low limiting oxygen index (LOI) of around 18%, making them susceptible to rapid and intense combustion, often ...
[86]
Characterisation of smoke in expanded polystyrene combustion
Decomposition and thermal degradation of PS gives off toxic fumes containing carbon monoxide (CO), carbon dioxide (CO2), water and soot (black smoke). Free ...
[87]
Standard Foam PP-PE Fabric Chair Test Burn | NIST
Apr 13, 2015 · An upholstered chair with a polyurethane foam burns completely within 6 minutes of ignition. A melt pool continues to burn after the cushion ...
[88]
The fire toxicity of polyurethane foams - Fire Science Reviews
Apr 21, 2016 · In addition to their flammability, polyurethanes form carbon monoxide, hydrogen cyanide and other toxic products on decomposition and combustion.
[89]
Editorial: Fire risk and prevention technologies of polymeric and ...
Apr 3, 2023 · Fire accidents caused by flammable polymeric materials have resulted over 40,000 deaths worldwide and regarded as a major challenge to be ...
[90]
Highly efficient flame retardancy and fire spread behavior of rigid ...
The findings revealed that with just 6 wt.% of flame retardants, the RPUF achieved the UL-94 V-0 rating, with a 41.1% reduction in peak heat release rate (pHRR ...
[91]
A Comprehensive Review of Reactive Flame Retardants for ... - NIH
Reactive flame retardants show higher thermal stability compared to additives due to their chemical bonding with polymer chains. The main advantage of using ...
[92]
Assessment of a Medium-Scale Polyurethane Foam Flammability Test.
Feb 1, 2008 · Six polyurethane foams of widely varying flame retardant levels have been tested in two modes: as four, fabric-wrapped cushions in a chair mock-up.
[93]
https://www.osha.gov/isocyanates
[94]
Isocyanates | NIOSH - CDC Archive
Breathing in isocyanates, or even getting these chemicals on skin, can cause or worsen asthma, a chronic disease.
[95]
Polyurethanes and Isocyanates and the Workplace - CWA-UNION.org
Although all of the isocyanate products are hazardous, Toluene Diisocyanate (TDI) is considered the most toxic.
[96]
A review of the emission of VOCs from polymeric materials used in ...
The available evidence indicates that VOCs can cause adverse health effects to the building occupants and may contribute to symptoms of 'Sick Building Syndrome' ...
[97]
Derivation of indoor air guidance values for volatile organic ... - NIH
Indoor Air Guidance Values (IAGVs) are derived for VOCs from polyurethane foam, using repeated dose inhalation studies, for those without existing values.
[98]
The Problems with Expanded Polystyrene (a.k.a. EPS or Plastic Foam)
Feb 12, 2025 · When polystyrene is used for food packaging, chemicals can leach into food and beverages. ... Instead, use shredded paper, perforated cardboard, ...
[99]
Polystyrene is safe for food in solid state, less so otherwise
Jun 3, 2022 · Polystyrene is considered safe for food use when in a solid state. However, heating can cause chemicals to leach from the foam and into the food.Missing: expanded | Show results with:expanded
[100]
Flame Retardants Used in Flexible Polyurethane Foam | US EPA
EPA is concerned that certain PBDEs are persistent, bioaccumulative, and toxic to both humans and the environment. The critical concern for human health is ...
[101]
Flame Retardants | National Institute of Environmental Health ...
Although flame retardants can offer benefits when added to certain products, increasing scientific evidence shows that many of these chemicals may harm animals ...
[102]
Flame Retardants in Discarded Foam Products - PMC - NIH
Mar 1, 2015 · The bare blocks used in “foam pits” may leach flame retardants more quickly than fabric-covered foam items. Studies to date suggest that use of ...
[103]
Study: Replacing Furniture and Foam Reduces Levels of Toxic ...
Mar 24, 2021 · Exposure to flame retardant chemicals has been linked to serious health issues, including cancer, neurotoxicity, thyroid disease and decreased ...
[104]
Health effects associated with faulty application of spray ... - PubMed
Results: All subjects reported fishy odors and developed acute watery and burning eyes, burning nose, sinus congestion, throat irritation, cough, dyspnea and ...<|separator|>
[105]
A Litigator's Guide to Polyurethane Foam Toxicity - Expert Institute
Aug 9, 2021 · Respiratory issues are the most common complication from isocyanate exposure. Health impacts range from shortness of breath and dry cough to ...
[106]
The problem with polystyrene foam - Environment America
Jun 22, 2022 · Expanded polystyrene foam is a big contributor to plastic pollution. It harms the health of both humans and animals and fills landfills and the environment ...
[107]
[PDF] How Takeout Containers — and Other Types of Plastic Foam — Hurt ...
Apr 1, 2025 · Plastic foam products rapidly generate microplastics when exposed to sunlight and friction, such as waves or abrasion from sand. 42,43 These ...
[108]
Biodegradation of polyether-polyurethane foam in yellow ... - PubMed
Jun 10, 2022 · Polyurethane (PU) is one of the mass-produced recalcitrant plastics with a high environmental resistance but extremely low biodegradability.
[109]
Microbial and abiotic degradation of fully aliphatic polyurethane ...
Biodegradation of the PUR foam in soil reveals that 77% of the soft segments are mineralized after 6 months reaching the final mineralization of 43%. The ...
[110]
Plastics: Material-Specific Data | US EPA
Nov 21, 2024 · This page describes the generation, recycling, combustion with energy recovery, and landfilling of plastic materials, and explains how EPA ...
[111]
Polyurethane Recycling and Disposal: Methods and Prospects - PMC
Aug 5, 2020 · Furthermore, when high temperatures are applied PU foams can release toxic compounds and carcinogens, like carbon monoxide, hydrogen cyanide and ...
[112]
Expanded polystyrene ban - Washington State Department of Ecology
Expanded polystyrene materials are difficult to recycle, and it's expensive. They aren't accepted in most of Washington's residential recycling programs and are ...
[113]
Taking plastic out of landfills - Harvard SEAS
Feb 27, 2024 · The majority of plastic just winds up in landfills, where it produces significant greenhouse gas emissions and not much else.
[114]
Bio-Based Polyurethane Foams: Feedstocks, Synthesis, and ... - NIH
May 7, 2025 · This review explores the main natural sources and their transformations into bio-polyols, the incorporation of bio-fillers into PU formulations,
[115]
Starting materials, processes and characteristics of bio-based foams
In this review, we focus on five biofoam products: namely bio-based PUs, PLA, starch, PHAs, and cellulose biofoam products, along with their properties and ...
[116]
Bio‐based polyurethanes: a comprehensive review on advances in ...
Jul 14, 2025 · Polyurethane foams (PUFs) from alternative sources can mitigate environmental and economic impacts. PUFs from alternative sources may ...
[117]
Bio-based rigid polyurethane foam prepared from apricot stone shell ...
Rigid polyurethane foams are a class of lightweight porous materials of tremendous interest due to their potential application and specific properties in ...
[118]
[PDF] Bio-based flexible polyurethane foams derived from Succinic Polyol
Polyurethane foams have widespread applications as temperature insulators, sound barriers and shock absorbers. The market requests for these materials growth ...
[119]
Biobased Foams: A Critical Review of Their Synthesis, Performance ...
Mechanical foaming is a simple polymer processing technique for the production of polymeric foams with vigorous mechanical agitation (high shear mixing) [3,4].
[120]
Biobased Ultralow-Density Polyurethane Foams with Enhanced ...
The study presents partly biobased polyurethane foams with enhanced recyclability that diminish the environmental footprint associated with waste disposal.<|separator|>
[121]
Plant-based substitute for fossil fuels developed for plastic foams
Jan 28, 2025 · An environmentally-friendly preparation of plant material from pine could serve as a substitute for petroleum-based chemicals in polyurethane foams.
[122]
Recent Developments in Biobased Foams and Foam Composites ...
Aug 29, 2023 · This review outlines recent developments in biobased foams based on biobased polyurethanes (BPU), biobased phenol formaldehyde (BPF) and cellulose nanofibers ( ...
[123]
Recent Advances in the Preparation and Application of Bio-Based ...
This article explores the preparation of various bio-based polyurethanes, their applications across different fields, and their anticipated future development ...
[124]
Nanocomposite Foams of Polyurethane with Carbon Nanoparticles ...
Jul 31, 2023 · In polymeric foams, carbon nanotubes can be included as efficient nanofillers to enhance the valuable properties of three-dimensional ...
[125]
Nanocomposites of Rigid Polyurethane Foam and Graphene ... - NIH
Feb 18, 2022 · The presence of GNPs led to superior enhancement of mechanical and thermal properties compared with those of resins containing CNTs, which may ...
[126]
Mechanical properties and morphology of nano-reinforced rigid PU ...
Jan 24, 2011 · Compression tests revealed an improvement of both compressive Young's modulus and compressive strength, and scanning electron microscope ...Missing: advancements | Show results with:advancements
[127]
Synthesis of nanoparticle-enhanced polyurethane foams and ...
Mar 1, 2018 · Enhanced mechanical and thermal properties of rigid polyurethane foam composites containing graphene nanosheets and carbon nanotubes. Polym ...
[128]
Nanoparticles Addition in PU Foams: The Dramatic Effect of Trapped ...
Aug 31, 2021 · The authors report that the nanoclays used in the study might be acting as nucleating agents during the formation of the foams. The presence of ...
[129]
Nanofibers (PU and PAN) and nanoparticles (Nanoclay and MWNTs ...
Aug 6, 2025 · By adding of MWNTs and nanoclay in foams, the foam morphology improved, in which cell density increased and smaller cells were obtained. The ...<|control11|><|separator|>
[130]
https://www.tandfonline.com/doi/full/10.1080/25740881.2025.2493869
[131]
Flexible polyurethane foams reinforced with graphene and boron ...
Dec 8, 2022 · In polyurethane foam, it is shown to have enhanced mechanical, thermal, electromagnetic shielding, and flame retardancy properties. Relatively ...
[132]
Multifunctional polymer foams with carbon nanoparticles
This review article considers the use of carbon nanoparticles in polymer foams, initially focusing on the important aspects of foam preparation, the main ...
[133]
PMMA nanocellular foams with enhanced physical properties
Apr 20, 2015 · As a result, it has been demonstrated that nanocellular foams present a significant improvement in several physical properties due to the ...
[134]
Nano-Enhanced Polymer Composite Materials: A Review of ... - MDPI
Properties such as thermal stability, electrical conductivity, strength, and stiffness-to-weight ratio have been significantly improved by introducing different ...