Polymeric Foam Materials Research Articles

High thermal insulation and compressive strength polypropylene microcellular foams with honeycomb structure

Global energy issues are becoming increasingly prominent, and have caused widespread attention. Lightweight, thermal insulation, environmentally friendly and recyclable polymeric foam materials exhibit a great application prospects in reducing energy consumption, saving resources and improving utilization. However, there are huge challenges in preparation of such high thermal insulation materials. Herein, recyclable, high mechanical strength and thermal insulation polypropylene (PP) foams were achieved by supercritical CO2 foaming in the presence of β nucleating agent (β-NAs). The obtained PP-β foam exhibited a variety of advantages, including high expansion ratio, continuous honeycomb polygonal cells, a very low thermal conductivity of 26.4 mW/m•K, strong tensile and compressive strength, as well as recyclable property. The accelerated crystallization process, decreased crystal size, and enhanced viscoelasticity caused by the β-NAs contributed to the formation of the multifunctional PP foams. The honeycomb polygonal cells greatly increased the curved path of heat propagation and reduced heat transfer efficiency, as well as enhanced the mechanical properties. Moreover, the compressed PP-β foam still possessed excellent thermal insulation property, as low as 37.1 mW/m•K. The recyclable multifunctional PP foam materials achieved by using physical foaming technology provided a potential solution for the preparation of multifunctional thermal insulation materials, which offered a big application prospect for polymer foam materials in the fields of reducing energy loss.

Novel Method for Preparing a High-Performance Auxetic Foam Directly from Polymer Resin by a One-Pot CO2 Foaming Process.

So far, negative Poisson's ratio foam (auxetic foam) is usually prepared by the transformation of conventional polymer foam, and it is a challenge to prepare auxetic foam directly from polymer resin. In this work, a novel method based on the synergism between the phase transition of water and the permeability rate difference of the CO2 blowing agent from air in the foaming process is put forward to prepare auxetic foam directly from the polymer resin. Using this method, herein, nylon elastomer (NE) foam with auxetic behavior is successfully prepared from NE resin by a one-pot CO2 foaming method inside an autoclave aided by water; the obtained auxetic foam has a Poisson's ratio value of -1.29 and has excellent tensile cycle stability and energy absorption performance. This method breaks through the bottleneck for preparing auxetic foams from the polymer resin directly, which is also green and environment-friendly. It is believed that the abovementioned method also applies to other thermoplastic polymers, which paves a way for designing and preparing multifunctional auxetic foam materials in the future via a one-pot CO2 foaming process. Furthermore, this work first demonstrates that the transformation between auxetic foam and positive Poisson's ratio foam is reversible due to the closed cell structure, which provides an opportunity to reversibly adjust the performance and the shape of polymer foam materials.

Experimental method for creep characterization of polymeric foam materials in media immersion

Polymeric flexible foam materials are widely used as damping materials in structural applications primarily to reduce unwanted system vibrations and related noise generation. Due to the viscoelastic nature of polymers and high compressibility of soft polymeric foams, their damping quality is strongly dependent on the overall loading situation, which occasionally means complex mechanical loading scenarios combined with specific ambient service conditions. In the case of superimposed constant compressive loading the deformation of the damping components is basically dependent on the fundamental creep tendency of certain material type and is also strongly influenced by service temperature and the surrounding contact media. Thus the chosen test methodology for proper creep characterization has to reflect these major influencing parameters.In this regard, a specific creep testing device was built up for the performance of small load compression creep experiments on soft foam specimens immersed in liquid media, which was mineral oil in the present study. Moreover, the thermo-mechanical behavior of the foam materials was investigated by dynamic-mechanical analysis (DMA). The resulting temperature-dependent modulus and damping characteristics showed a good correlation with the corresponding creep behavior, enabling a rough estimation of the creep tendency within corresponding temperature ranges.

Synchrotron CT imaging of lattice structures with engineered defects

Understanding mechanical failure, crack propagation, and compressive behavior at the micrometer scale is essential for tailoring material properties for structural performance in cellular materials. Typically, modeling of traditional polymer foam materials is clouded by the lack of control in material morphology and its inherent stochastic structure. Additive manufacturing with sub-micrometer resolution provides a direct path for experimenters to specifically tailor structures needed by modelers to explicitly probe mechanical performance. Using laboratory-based 3D X-ray computed tomographic imaging (CT), the examination of deformation and damage provides a critical path to understand how these soft materials behave. Additionally, synchrotron CT yields realistic information at higher strain rates to directly validate the robustness of our finite element modeling. For this study, nanolithographic printing was employed to generate a series of engineered lattices with increasing levels of defects through the random removal of ligaments. These structures were mechanically tested and imaged with laboratory-based microCT. Additionally, synchrotron experiments were conducted in which the structures were imaged in 3D at 14 Hz during compression at a 0.4 s−1 strain rate. These 3D images show the changes in the structure as the ligaments bend, buckle and fracture in real time. This technique provides a robust framework for developing our methodologies and future exploration of engineered structures.

Water-based hybrid coatings toward mechanically flexible, super-hydrophobic and flame-retardant polyurethane foam nanocomposites with high-efficiency and reliable fire alarm response

Flammability feature of combustible polymer foam materials often causes massive casualties and property loss, and it is therefore urgent to develop a green and high-efficiency strategy that can reduce or avoid the fire blaze disasters. Here, an extremely simple water-based coating approach is proposed to prepare mechanically flexible, super-hydrophobic and flame-retardant polyurethane (PU) foam nanocomposites with high-efficiency fire warning response. The hybrid ammonium polyphosphate (APP)/graphene oxide (GO) is decorated onto the PU foam surface via electrostatic interactions followed by surface silane functionalization. Interestingly, the silane and APP molecules present selective distributions on the GO and thus form micro-/nano- rough surface with low water affinity to achieve super-hydrophobicity (e.g. water contact angle of ~158.4°). Meanwhile, such hybrid APP/GO/silane coatings produce synergistic flame resistance for the PU foam materials, which is attributed to the formation of compact and uniform P-Si elements co-covered rGO layer on the foam surface. Further, the hybrid coatings can provide high-efficiency fire warning response under complicated conditions, e.g. flame detection response time of only ~2.0 s and excellent fire early warning time in pre-combustion (e.g. 11.2 s at 300 °C). Therefore, this work provides new perspectives to design and develop multi-functional coatings for fire safety and prevention applications.

Effect of nanoparticles orientation on morphology of polymeric nanocomposite foams: preparation of foamed nanocomposite fibers by supercritical carbon dioxide

ABSTRACT Polymeric foams have received increasing attention in both academic and industrial communities. Using of nanoparticles as heterogeneous nucleation agent has been verified as one of the most valid means to enhance cell nucleation and improve cell morphology. However, few researches have been conducted to investigate the effect of the nanoparticles’ spatial orientation on their nucleation efficiency. In this work, to study the influence of the orientation of nanoparticles on their performance in improving morphology of polymeric foam, thermoplastic polyurethane (TPU) composite fibers with different nanoparticles (carbon nanotubes, graphene and SiO2) were prepared by using different traction speeds. The different traction speeds lead to different orientation state of the nanoparticles which then resulted different nucleation effect. It was found that carbon nanotubes (CNTs) were easily oriented and aligned along the fiber length direction under the high traction speed, while graphene and SiO2 nanoparticles did not show orientation under the traction speed in this study. As a result, the foam of TPU/CNTs composite fibers from high traction speed exhibited a much smaller cell size and higher cell density compared to the foams of the fibers from low traction speeds, while TPU/graphene, and TPU/SiO2 composite fibers with different traction speeds showed almost similar cell size and size density after foaming, indicating that the orientated nanoparticles possessed higher heterogeneous nucleation efficiency. To our best knowledge, this work, for the first time, demonstrated the high nucleation effect of the aligned nanoparticles, which hopefully open a new path for improving the cell morphology of polymeric foam materials.

Research on the Effect of Imprecise Size Foam Samples on Acoustic Measurements in Impedance Tube

Polymer foam materials are very commonly used acoustic materials for absorbing sound energy in noise control engineering, because of their higher porosity and light in weight. The acoustic characterization of these materials namely; absorption coefficient and transmission loss are measured using impedance tube, reverberation room method and intensity methods. Among these three impedance tube is the most popular method in laboratory condition. Here the sample size plays a main role in the accurate characterization acoustic materials by using the impedance tube. The present paper discusses effect of variation in the sample size on their acoustic measurements. The foam sample are prepared using Resistance wire foam cutter(RWFC). Their absorption coefficient and transmission loss for large and small samples with variations in sample dimensions are measured and compare with ideal dimension results. A detailed measured data and analysis are done to understand the effect of undersized and oversized foam samples on absorption coefficient and transmission loss results as a function of frequency. The results show that the variations in sample size has immense effect of measured results. The results presented in this study becomes a guideline for characterizing acoustic materials using impedance tube.

Reinforcing the Tensile Strength of Lightweight and Soft BBIR/EVA Foam with Organic Modified Potassium Titanate Whisker and its Thermal Insulation Performance

It is agreed that the mechanical properties and density of polymer foam material are contradictory. At present, the preparation of low density and high-strength foam material is still a great challenge. In this paper, potassium titanate whisker (PTW) with reinforcement and heterogeneous nucleation modified by γ‑methacryloxypropyltrimethoxysilane (KH-570) was used to prepare brominated butyl rubber/ethylene-vinyl acetate copolymer (KPTW/BBIR/EVA) composite foam through molding foaming technology. Then the physical mechanical and thermal stability properties of it were tested with universal testing machine and thermal gravity analysis (TGA). The effect of KPTW on morphology (cell size, density and distribution) of BBIR/EVA foams was demonstrated by scanning electron micrograph (SEM). The results indicate that the tensile strength of KPTW/BIIR/EVA foam was increased by 75% compared with that of BIIR/EVA foam (1.23 MPa) when its density was 0.25 g/cm3. By introducing KPTW, the mean cell size of PTW/BIIR/EVA foam was reduced from 436.6 to 40.9 μm for KPTW/BIIR/EVA foam. Meanwhile, the KPTW as a foaming nucleating agent increases cell density of KPTW/BIIR/EVA foam and thus increased its thermal insulation performance.

Estimation of Volatile Organic Compounds (VOCs) and Human Health Risk Assessment of Simulated Indoor Environment Consisting of Upholstered Furniture Made of Commercially Available Foams

This study was conducted for the qualitative and quantitative determination of volatile organic compounds (VOCs) and total volatile organic compounds (TVOC) from polymeric foam materials used in upholstered furniture. Six different types of foams viz. Highly elastic foam K5040, standard PU foam N5063, bonded polyurethane foam R100, viscoelastic foam V5020, self-extinguishing foam KF5560, and foam rubber were used. Short-term and long-term (24, 48, 72, 672 hours (28 day)) measurements were done to differentiate the role of primary emissions (present in new products) and secondary emissions (due to chemical reactions in material or slowly released due to the porous structure of material). The samples were collected using a small-space sampling chamber at a temperature of 23°C and a humidity of 50% depending on the aspect of time. The concentrations of VOC and TVOC were identified and quantified using a Gas chromatography–Mass spectroscopy (GC-MS) based method. Based on the VOC measurements, the standard room concentrations were simulated to estimate the human health risk assessment for all six types of foams. The results of simulations suggest no possibility of human health risk for the very long period (28 days), as the estimated values were found to be much below the prescribed limits.

A Comparative Life Cycle Assessment of Meat Trays Made of Various Packaging Materials

In light of the debate on the circular economy, the EU strategy for plastics, and several national regulations, such as the German Packaging Act, polymeric foam materials as well as hybrid packaging (multilayered plastic) are now in focus. To understand the environmental impacts of various tray solutions for meat packaging, a comparative environmental assessment was conducted. As an environmental assessment method, a life cycle assessment (LCA) was applied following the ISO standards 14040/44. The nine packaging solutions investigated were: PS-based trays (extruded polystyrene and extruded polystyrene with five-layered structure containing ethylene vinyl alcohol), PET-based trays (recycled polyethylene terephthalate, with and without polyethylene layer, and amorphous polyethylene terephthalate), polypropylene (PP) and polylactic acid (PLA). The scope of the LCA study included the production of the tray and the end-of-life stage. The production of meat, the filling of the tray with meat and the tray sealing were not taken into account. The results show that the PS-based trays, especially the mono material solutions made of extruded polystyrene (XPS), show the lowest environmental impact across all 12 impact categories except for resource depletion. Multilayer products exhibit higher environmental impacts. The LCA also shows that the end-of-life stage has an important influence on the environmental performance of trays. However, the production of the trays dominates the overall results. Furthermore, the sensitivity analysis illustrates that, even if higher recycling rates were realised in the future, XPS based solutions would still outperform the rest from an environmental perspective.

Fabrication of PEI‐grafted porous polymer foam for CO2 capture

ABSTRACTA polymer foam material with both the open‐cell porous structure and the polyethylenemine (PEI)‐grafted inner face was constructed for CO2 capture. The porous poly(tert‐butyl acrylate) foam was first prepared via a concentrated emulsion polymerization, and then the carboxyl groups were introduced on the interface of porous polymer after the hydrolysis reaction. Subsequently, the surface of the foam was grafted with PEI, and finally the PEI‐grafted porous polymer foam designed as a CO2 capture material was obtained. The structures of the foams were characterized by infrared spectroscopy, EDS, and SEM. The CO2 adsorption properties were measured by adsorption/desorption cycles. As a result, the polymer foam contained a large number of amine groups (13.9 wt % N), and therefore possessed a high CO2 adsorption capacity (5.91 mmol g−1 at 40°C and 100 kPa). In addition, they also exhibited high CO2 adsorption rate, good selectivity for CO2‐N2 separation, and good stability according to CO2 cyclic adsorption/desorption test. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47844.

Prepare Foam with Injection Molding Method in Acrylonitrile-Butadiene-Styrene (ABS) Matrix Using Chemical Foam Agent

In this study, it is aimed to decrease the weight of the material by using polymer foam materials with lower density instead of commercial polymers which have wide usage area. For this purpose, polymer foam was produced by using an acrylonitrile butadiene styrene (ABS) matrix and an endothermic chemical foam agent using injection molding method. The foam cell morphology, shell layer thickness and mechanical properties of the final part were investigated taking into consideration the weight-changing ratios of the foam agent content (1-1,5-2-2,5-3%).

In situ reactive self-assembly of a graphene oxide nano-coating in polymer foam materials with synergistic fire shielding properties

We report a facile and green in situ reactive self-assembly strategy to achieve a compact and ultrathin GO nano-coating bonded onto silicone rubber foam surface, producing excellent high-temperature resilience and synergistic fire resistance.

Fabrication and characterization of waterborne polyurethane/silver nanocomposite foams

Nowadays the waterborne polyurethane (WPU) is a newly developed polymer foam material as a replacement for conventional organic solvent‐based polyurethane (PU). Nevertheless, the WPU foams exhibit some drawbacks such as inferior mechanical strength, low thermal and dimensional stability, which inhibits its large‐scale application at present. So a series of novel WPU/silver nanocomposite foams was successfully prepared by mechanical foaming method. The effect of silver nanoparticles (nano Ag) content on the morphology, thermal behavior, air permeability, water vapor transmission rate (WVT), mechanical, and antibacterial properties of WPU/Ag nanocomposite foams were systematically investigated. The results revealed that the nano Ag were uniformly dispersed in WPU matrix and facilitated cell growth, leading to enhanced mean pore size, thermal stability, air permeability, and WVT value of nanocomposite foams. About 122% improvement in the air permeability and 28% improvement in the WVT value were obtained when the nano Ag content extended from 0 to 4 wt%. It was found that the nano Ag content had great influence on tensile strength and elongation at break. When nano Ag content was 2 wt%, the nanocomposite foam exhibited the maximum tensile strength value of 1.26 MPa. Moreover, because of the addition of nano Ag, the nanocomposite foam showed bacteriostatic rate of 98.23% and 97.38% against Escherichia coli and Staphylococcus aureus, respectively. POLYM. COMPOS., 40:1492–1498, 2019. © 2018 Society of Plastics Engineers

Static simulation to horse shoes alternative materials based basic polymeric foam reinforced fiberglass with ANSYS software

In this journal, we used Finite Element Method (FEM) calculations based on ANSYS software. The software will involves the value of the material properties. Then, will used to simulate the manufacture of horse shoe, when the horse stood silent, for fiberglass reinforced polymer materials and compared with the usual materials for horse shoe, the Mild Carbon Steel (A36) so that will be obtained which is the best between the two materials. In this simulation work, the horse shoe receives a load of 500 kg. From this simulation we will obtain Equivalent Stress, Normal Stress on each axis (X, Y, Z) from the loading direction experienced by horse shoes. Equivalent equivalence values of 0.21509 MPa polymeric foam while Mild Carbon Steel (A36) 0.1034 MPa and normal polymeric foam voltage values for X-axis 0.016426, Y -0.007111 and Z 0.0695, while Normal Stress from Mild Carbon Steel (A36) for X axes 0.02233, Y 0.0204 and Z 0.047. The simulation results provide an understanding of the normal force resistance of polymeric foam materials for Mild Carbon Steel (A36) materials, whereas for polymeric foam materials the equivalent stress is superior to Mild Carbon Steel (A36)

Radial Inertia Effect on Dynamic Compressive Response of Polymeric Foam Materials

Polymeric foams have been extensively used in shock isolation applications because of their superior shock or impact energy absorption capability. However, as a type of soft condensed matter, the highly nonlinear, heterogeneous, and dissipative behavior of polymeric foams may result in an ineffective mitigation or isolation to shock/blast loading. To meet certain desired shock mitigation or isolation requirements, the polymeric foams need to be experimentally characterized to obtain their intrinsic material response. However, radial inertia during dynamic compression has become a severe issue and needs to be fully understood. In this study, we developed an analytical method to calculate the additional stress induced by radial inertia in a polymeric foam specimen. The radial inertia is generally caused by Poisson’s effect and associated with three different mechanisms – axial strain acceleration, large deformation, and Poisson’s ratio change. The effect of Poisson’s ratio change during deformation on radial inertia was specifically investigated for hyperelastic foam materials, and verified with experimental results obtained from Kolsky compression bar tests on a silicone foam.

Desain dan fabrikasi patok rintangan lapangan golf bahan polymeric foam yang diperkuat serat tandan kosong kelapa sawit

A golf course with obstacles in the forms of water obstacle and lateral water obstacle marked with the stakes which are called golf course obstacle stake in this study. This study focused on the design and fabrication of the golf course obstacle stake with a solid cylindrical geometry using EFB fiber-reinforced polymeric foam composite materials. To obtain the EFB fiber which is free from fat content and other elements, EFB is soaked in the water with 1% (of the watre total volume) NaOH. The model of the mould designed is permanent mould that can be used for the further refabrication process. The mould was designed based on resin-compound paste materials with talc powder plus E-glass fiber to make the mould strong. The composition of polimeric foam materials comprised unsaturated resin Bqtn-Ex 157 (70%), blowing agent (10%), fiber (10%), and catalyst (10%). The process of casting the polimeric foam composit materials into the mould cavity should be at vertical casting position, accurate interval time of material stirring, and periodical casting. To find out the strength value of the golf course obstacle stake product, a model was made and simulated by using the software of Ansys workbench 14.0, an impact loading was given at the height of 400 mm and 460 mm with the variation of golf ball speed (USGA standard) v = 18 m/s, v =35 m/s, v = 66.2 m/s, v = 70 m/s, and v = 78.2 m/s. The clarification showed that the biggest dynamic explicit loading impact of Fmax = 142.5 N at the height of 460 mm with the maximum golf ball speed of 78.2 m/s did not experience the hysteresis effect and inertia effect. The largest deformation area occured at the golf ball speed v = 66.2 mm/s, that is 18.029 mm (time: 2.5514e-004) was only concentrated around the sectional area of contact point of impact, meaning that the golf course obstacle stakes made of EFB fiber-reinforced polymeric foam materials have the geometric functional strength that are able to absorb the energy of golf ball impact. Keywords: Composite, Polymeric Foam, EFB Fiber, Tension Distribution, Ansys Workbench 14.0

Design and fabrication hazard stakes golf course polymeric foam material empty bunch (EFB) fiber reinforced

A golf course with obstacles in the forms of water obstacle and lateral water obstacle marked with the stakes which are called golf course obstacle stake in this study. This study focused on the design and fabrication of the golf course obstacle stake with a solid cylindrical geometry using EFB fiber-reinforced polimeric foam composite materials. To obtain the EFB fiber which is free from fat content and other elements, EFB is soaked in the water with 1% (of the watre total volume) NaOH. The model of the mould designed is permanent mould that can be used for the further refabrication process. The mould was designed based on resin-compound paste materials with talc powder plus E-glass fiber to make the mould strong. The composition of polimeric foam materials comprised unsaturated resin Bqtn-Ex 157 (70%), blowing agent (10%), fiber (10%), and catalyst (10%). The process of casting the polimeric foam composit materials into the mould cavity should be at vertical casting position, accurate interval time of material stirring, and periodical casting. To find out the strength value of the golf course obstacle stake product, a model was made and simulated by using the software of Ansys workbench 14.0, an impact loading was given at the height of 400 mm and 460 mm with the variation of golf ball speed (USGA standard) v = 18 m/s, v = 35 m/s, v = 66.2 m/s, v = 70 m/s, and v = 78.2 m/s. The clarification showed that the biggest dynamic explicit loading impact of Fmax = 142.5 N at the height of 460 mm with the maximum golf ball speed of 78.2 m/s did not experience the hysteresis effect and inertia effect. The largest deformation area occurred at the golf ball speed v = 66.2 mm/s, that is 18.029 mm (time: 2.5514e-004) was only concentrated around the sectional area of contact point of impact, meaning that the golf course obstacle stakes made of EFB fiber-reinforced polymeric foam materials have the geometric functional strength that are able to absorb the energy of golf ball impact.

Novel porous bioabsorbable phosphate glass matrix nanocomposites incorporating trisilanolphenyl polyhedral oligomeric silsesquioxane prepared by extrusion

Phosphate glass matrix nanocomposites containing trisilanolphenyl polyhedral oligomeric silsesquioxane (POSS) were investigated for the first time to accelerate efforts to develop novel hybrid phosphate glass/POSS composites with enhanced benefits. Tin fluorophosphate glass (Pglass) having ultra-low glass transition temperature (Tg) was utilized as the matrix material in extrusion at relatively low processing temperature (i.e., 270±10°C) compared to that of typical borosilicate and sodalime glasses. The resulting nanocomposites materials were highly porous due to evaporation of condensed water produced in situ from polysiloxane condensation reaction between the Pglass and POSS during the extrusion process. As the amount of POSS was increased in the Pglass matrix material, the glass transition temperature was significantly changed by the bulky POSS molecules. The novel porous nanocomposites should find a number of uses in applications at elevated temperatures where conventional organic polymer foam materials are not useable.

Increased X-ray Visualization of Shape Memory Polymer Foams by Chemical Incorporation of Iodine Motifs.

Shape memory polymers can be programmed into a secondary geometry and recovered to their primary geometry with the application of a controlled stimulus. Porous shape memory polymer foam scaffolds that respond to body temperature show particular promise for embolic medical applications. A limitation for the minimally invasive delivery of these materials is an inherent lack of X-ray contrast. In this work, a triiodobenzene containing a monomer was incorporated into a shape memory polymer foam material system to chemically impart X-ray visibility and increase material toughness. Composition and process changes enabled further control over material density and thermomechanical properties. The proposed material system demonstrates a wide range of tailorable functional properties for the design of embolic medical devices, including X-ray visibility, expansion rate, and porosity. Enhanced visualization of these materials can improve the acute performance of medical devices used to treat vascular malformations, and the material porosity provides a healing scaffold for durable occlusion.