Polyethylene Foam Research Articles

Superior electromagnetic wave absorption performance of Fe3O4 modified graphene assembled porous carbon (mGAPC) based hybrid foam

High performance Fe3O4 modified graphene assembled porous carbon (mGAPC) based epoxy paint coated on Polyethylene (PE) foam is realized by spray technique to fabricate light weight electromagnetic absorbers. The mGAPC as a pigment in a standard composition of commercial paint was optimized and the influence of solvent and additives are studied to achieve X-band (8.2–12.4 GHz) electromagnetic wave absorption (EA) in the hybrid foam (HF). From the comparative studies, the hybrid foams obtained from epoxy paint with toluene as solvent (without Mn-octate as additive) showed a Reflection Loss (RL) −19 dB (in the range of 8.3–8.7 GHz), which was further increased with the coating cycles up to −43 dB (in 10.2–11.2 GHz).The observed rise is attributed to increase in localized interfacial polarization that arises at the combined interfaces of mGAPC. The result showed 99% loss, which projects a promising EA paint for practical applications. Further thickness dependent studies of EA in Paint Coat HF1, reveals that with increasing thickness from 0.3 to 2 mm, the RL also increases from −19 to −43 dB with changing absorption band. The superior EA properties are correlated to the percolation threshold, pigment dispersibility and further correlated to the strong absorption, destructive interference, multiple internal reflections and interfacial polarization of the radiation in the hybrid foam. Moreover, considering the paint lowest thickness ∼0.3 mm with −19 dB of RL, the hybrid foam promises a cost-effective, fine, light-weight EA/RL material for secure electronic devices and packaging in civil and defence applications.

Reinforcement mechanisms of recycled glass beads reinforced thermoplastic foams under dynamic compressions

Polymer foams and recycled glass beads (GBs) are both promising lightweight porous materials with excellent energy-absorption performance. The dynamic response of polyethylene foams reinforced by GBs have been rarely reported. In this study, the mechanical behaviors and dynamic stress enhancement mechanisms of GBs reinforced thermoplastic polyethylene foams are experimentally investigated, and verified by finite-element (FE) numerical predictions where the GBs are explicitly modeled based on the characteristics of microstructural constituent materials. It is reported that with increasing loading rates, strain and stress localizations are more pronounced around hollow cells, GBs and the bridge regions. Ascribed to the interaction between GBs and foam matrix, higher strain rate also contributes to enhancements of elastic properties and plastic stress of GBs reinforced foams with lower and higher reinforcement volume fractions (f), respectively. In comparison with the case of low loading rate, increasing loading rate gives rise to the damage initiation in GBs at lower compressive strain, and the damage initiation leads to the plastic stress softening of foam composites. The results also demonstrate that the f and volume fraction of polymer (F) have negative and positive influence, respectively, on the energy absorption efficiency of GBs reinforced foams.

A boundary migration model for imaging within volumetric scattering media

Effectively imaging within volumetric scattering media is of great importance and challenging especially in macroscopic applications. Recent works have demonstrated the ability to image through scattering media or within the weak volumetric scattering media using spatial distribution or temporal characteristics of the scattered field. Here, we focus on imaging Lambertian objects embedded in highly scattering media, where signal photons are dramatically attenuated during propagation and highly coupled with background photons. We address these challenges by providing a time-to-space boundary migration model (BMM) of the scattered field to convert the scattered measurements in spectral form to the scene information in the temporal domain using all of the optical signals. The experiments are conducted under two typical scattering scenarios: 2D and 3D Lambertian objects embedded in the polyethylene foam and the fog, which demonstrate the effectiveness of the proposed algorithm. It outperforms related works including time gating in terms of reconstruction precision and scattering strength. Even though the proportion of signal photons is only 0.75%, Lambertian objects located at more than 25 transport mean free paths (TMFPs), corresponding to the round-trip scattering length of more than 50 TMFPs, can be reconstructed. Also, the proposed method provides low reconstruction complexity and millisecond-scale runtime, which significantly benefits its application.

Developments on auxetic closed cell foam pressure vessel fabrications

Auxetic foam can have higher indentation resistance, better protection under impact and higher vibration damping than conventional foam. Unlike auxetic open cell foam, with established, commercially viable options for manufacturing, methods for making auxetic closed cell foam are not established. We revisited pressure-vessel methods, proposed in 1996, for making auxetic closed cell foam. We processed low-density polyethylene foam for 6 h at 400–700 kPa and 100 °C, causing foams to shrink by a factor of two to five. The volumetric compression kinked cell walls, producing negative Poisson’s ratios as low as −0.2 and Young’s moduli from 0.2 to 1.2 MPa. Trends between applied volumetric compression and Poisson’s ratio agree with those for open cell foam—initially decreasing to negative values as volume reduced by a factor of two after processing, then plateauing or slightly increasing as volume decreased by a factor of two to five. Foams of different sizes and shapes (15–75 mm sides) processed in the same conditions (700 kPa, 6 h, 100 °C) shrank evenly in all three axes and had similar final volume ratios. We noticed a long settling period, of up to three months, where foams slowly shrank. Placing foam in a vacuum after processing reduced the settling period to within 24 h.

Polymer‐decorated daikon‐based solar evaporators for efficient interfacial water evaporation

Interface solar evaporator has been recognized as a potential device for extracting freshwater from non-potable water. Biomass like daikon is an excellent candidate for fabricating solar evaporators because of its good hydrophilia and porous structure, which facilitates water transfer and vapor release. Besides, polymers like polydopamine and polypyrrole (abbreviated as PDA and PPy, respectively) possessing wide spectrum absorption are fascinating candidates for efficient solar evaporators. Herein, PDA-decorated daikon and PPy-decorated daikon (abbreviated as PDA-DK and PPy-DK, respectively) solar evaporators have been developed for vapor production. Due to polyethylene foam can effectively concentrate the heat on the photothermal materials, under 1-solar intensity, the water vaporization rates of PDA-DK and PPy-DK are enhanced to 1.50 and 1.60 kg m−2 h−1, and the relative solar thermal efficiencies are improved by about 40%, from 49.51% and 58.65% to 89.01% and 98.97%, respectively. Thanks to the super hydrophilicity and high water storage capacity, the PPy-DK has the self-cleaning ability and can effectively desalinate seawater with a desalination rate of around 1.6 kg m−2 h−1. Moreover, both solar evaporators exhibit considerable stability in evaporation rate, with no significant changes within 15 cycles. Outdoor experiments demonstrate that these two solar evaporators are capable of desalinating saltwater and cleaning dye wastewater.

Influence of HT on energy absorption in CLS compression process

ABSTRACT Paper honeycomb and EPE are widely used in the field of packaging protection and safety transportation. Given the cushioning and protective function of unilateral and bilateral composite layered structures (CLSs) including polyethylene foam (EPE) and paper honeycomb, this work focused on analyzing the energy absorption (EA) and compression deformation of honeycomb thickness (HT) CLS under diverse drop impact (DI) status. Experimental observation showed that the increase of HT can improve the impact resistance of EPE and its CLSs. For the CLS with the HTs of 10, 15, 20, and 25 mm, the increase of paper HT may reduce the EA at low impact energy, while enhancing the EA capability at high impact energy. However, the EA of CLSs with a large HT of 70 mm is relatively poor. For the same drop weight mass or impact energy, the stroke efficiency (SE) and specific energy absorption (SEA) of the unilateral CLS with the same HT are, respectively, increased by 39.1% and 16.2%, so the EA of the unilateral CLS is superior to the bilateral CLS.

Polyethylene Foam in Seamless Insulation Systems

Polymer Science: Peer Review Journal Polyethylene Foam in Seamless Insulation Systems Karapet Ter Zakaryan1 and Aleksey Zhukov2* 1TEPOFOL Ltd., Russia 2National Research Moscow State University of Civil Engineering (NRU MSUCE), Russia *Corresponding author: Aleksey Zhukov, National Research Moscow State University of Civil Engineering (NRU MSUCE), Yaroslavl sh. 26, Moscow, Russia Submission: March 07, 2022;Published: April 18, 2022 DOI: 10.31031/PSPRJ.2022.03.000565 ISSN: 2770-6613 Volume3 Issue3

Effect of polyethylene foam on dynamic cushioning energy absorption of paper corrugation tubes

Effect of polyethylene foam on dynamic cushioning energy absorption of paper corrugation tubes

Achieving low‐thermal conductivity and high β phase in PVDF/PMMA blend foams via low‐pressure microcellular foaming

AbstractPolyvinylidene fluoride (PVDF) foam exhibits wider applications than traditional foams such as polyethylene and polystyrene foams due to its good corrosion resistance, flame retardant and wide operating temperature range. However, PVDF is difficult to foam and rigorous operating conditions including high pressure and high temperature were unavoidably adopted to prepare PVDF foams. Herein, microcellular PVDF foam was successfully fabricated with the combination of adding polymethylmethacrylate (PMMA) and batch foaming at mild processing condition. Compared to the pure PVDF foam with a low‐expansion‐ratio of 1.1 times, the PVDF/PMMA (70/30) blend foam showed an expansion ratio as high as 20 times together with a small cell size of approximately 5 μm. Additionally, the prepared PVDF/PMMA blend foam exhibited a low‐thermal conductivity (0.039 w m−1 k−1) and high content of β‐phase crystal (95%), which shows promising application in areas like electronic devices, thermal insulation and packaging materials.

Salt leaching as a green method for the production of polyethylene foams for thermal energy storage applications

AbstractMaterials able to store thermal energy can be a useful strategy to reduce energy consumption of buildings and to decrease greenhouse gases emissions. In this work, for the first time, the technique of salt leaching has been used to produce novel polyethylene foams containing different amounts of a microencapsulated phase‐change material (PCM) with a melting point of 24°C, to be potentially applied in building insulation. The microstructural, thermal, and mechanical properties of produced foams have been comprehensively investigated. The prepared foams were characterized by high values of open porosity (about 60%) and by density values around 0.4 g/cm3. Infrared thermography analysis demonstrated that the time required from the samples to reach a set temperature, thanks to the presence of PCM, was up to two times higher with respect to the reference foam. Therefore, these materials could store/release an interesting amount of thermal energy. Shore‐A measurements evidenced that the addition of PCM generally led to a softening of the foams. Tensile mechanical tests confirmed the softening effect provided by the addition of the microcapsules, with a decrease of the stiffness and of the strength of the material. Interestingly, strain‐at‐break values were considerably increased upon PCM introduction.

Investigating the impact behavior of wrestling mats via finite element simulation and falling weight impact tests

In this paper, a novel approach is used to represent the viscoelastic behavior of cross-linked polyethylene foams at high strain rate: a compressible hyperelastic material model is combined with the Rayleigh damping method. We developed finite element models to simulate the impact tests described in the international assessment protocol of wrestling mats. The accuracy of the finite element analysis was validated with experimental data. We showed the nonlinear viscoelastic nature of the foam material by determining the relationship between the damping ratio and maximum compressive strain. We demonstrated the applicability of the method through the quality assessment of wrestling mats, and determined the minimum required thickness to prevent traumatic head injuries. The modeling and testing method can be implemented in the study of sandwich structures, thus the design process can be simplified. With further development, our approach can be used to design multilayered wrestling mats with better energy absorbing characteristics.

Investigating polymeric foam materials as compressible layer for tunnelling in squeezing ground conditions

Installation of a compressible layer between primary support and secondary lining is a feasible solution to decrease damage of the secondary lining induced by the time-dependent deformation in the squeezing tunnel. Laboratory tests and numerical analysis were conducted to investigate the feasibility of the polymeric foam for the compressible layer in a squeezing tunnel. The PU (Polyurethane) foam (density 70 kg/m3–100 kg/m3) and PE (Polyethylene) foam (density 90 kg/m3–130 kg/m3) are chosen as candidate filling materials of the compressible layer. The stress-strain curves of the candidate materials show a clear stress plateau stage, and the deformation capability and stress of the plateau stage can meet the requirements of the compressible layer. PU foam with density 80 kg/m3 is finally selected due to its energy absorption capability for the compressible layer. The performances of the PU foam compressible layer under uniform and nonuniform squeezing deformation are simulated, the results show that the stress and failure zone of the secondary lining can be clearly decreased by the PU foam compressible layer, and the tension stress of secondary lining induced by non-uniform tunnel deformation can be avoided. The mechanical performance of the PU foam indicates the feasibility of using polymeric foam as the compressible layer in squeezing ground conditions.

Decelerating and recovery techniques for hypervelocity projectiles

Recovering the projectile, target debris and assessing damage effects are important in evaluating the performance of hypervelocity systems and in developing protective countermeasures. We report the results of experiments and simulations that have been conducted to assess the viability of decelerating and recovering hypervelocity projectiles with masses >1.5 kg and velocities >1.7 km/s. The objectives were to retain projectile integrity and retrieve data from onboard diagnostics. This required the minimization of impact loads and frictional heat generation with respect to the selection of deceleration and recovery materials. According to the requirements of decelerating and recovering the hypervelocity projectile, an anti-flaming expandable polyethylene foam, an anti-flaming expandable polystyrene foam, an anti-flaming sponge and an anti-flaming expandable polyurethane foam were chosen as the decelerating materials in the verification test while paraffin was chosen as the recovery material. Based on their damage characteristics under impact and the cost, the anti-flaming sponge and the paraffin were selected as the decelerating material and recovery material respectively. Deceleration effects on the moving projectile were obtained by numerical simulation. The device was designed and installed with anti-flaming sponge and paraffin, which successfully recovered the projectile with a mass of 1.89 kg at a velocity of 1.90 km/s. The projectile velocity profile was successfully obtained in the deceleration and recovery materials.

Microbial Destruction of Polymeric Materials: Polyethylene Foam, Ethylene Vinylacetate, and Rubber

Microbial Destruction of Polymeric Materials: Polyethylene Foam, Ethylene Vinylacetate, and Rubber

RFID System for Respiratory Rate Monitoring

In this work, an RFID system was developed to monitor the respiratory rate. This monitoring was based on variations in the Received Signal Strength Indicator (RSSI) by the reader due to respiratory movements. In some breath measurement configurations, the maximum read range was greater than 1 m, which is the distance considered in the measurement configurations described in some scientific papers. The RSSI data, obtained by reading the RFID tag, were processed using the Daubechies wavelet of order 3 (db3) and considering three levels of signal decomposition. Less noisy breathing signals were obtained in the measurements with the participant seated and the RFID tag with the polyethylene foam on the abdomen. The respiratory frequencies acquired from the variations of the RSSI parameter were validated by comparison with the results obtained using a vital signals monitor.

Experimental study of mechanical properties of Sisal/banana fiber hybrid sandwich composite

Composites are becoming increasingly popular as a result of their useful features, like higher strength-to-weight ratio, higher modulus-to-weight ratio, resistance to corrosion and abrasive resistance. The purpose of this study is to examine the impact of moisture absorption on the mechanical characteristics of hybridized sandwich composite scaffolds made from epoxy resin, strengthened by woven fabrics of banana (B) and Sisal (S) fibers, and a fundamental layer of polyethylene foam (F). The buildings in this investigation were made using a hand layup approach. Samples of the composite are submerged in room-temperature water for varying amounts of time to determine the fibers' water absorption qualities. Several sandwich composite constructions are made and compared to a composite made from 100% Sisal fiber. According to the results, including foam into the Sisal/banana fibres increases their mechanical qualities. However, the composites' tensile, flexural, and impact strengths were diminished after prolonged exposure to water due to water permeating the fibre/matrix contact.

High‐performance thermal insulator based on polymer foam and silica xerogel

AbstractIn this work, methyltrimethoxysilane (MTMS) was used as a precursor, n‐hexadecyltrimethylammonium bromide (CTAB) as a surfactant, and EtOH/H2O as a co‐solvent, while 10 mM HCl and urea were used as acid and base catalysts to prepare silica xerogels and xerogel inside the cells of a polyethylene (PE) foam via a sol–gel process combined with ambient pressure drying. The xerogels and PE‐silica xerogel foams were characterized by scanning electron microscope (SEM), Brunauer–Emmett–Teller method (BET), and thermal conductivity. The results indicate that the xerogels have a three‐dimensional nanoporous structure, and the specific surface areas of the SiO2 xerogel and PE‐xerogel foam are 536 and 377 m2/g, respectively. The PE‐xerogel foam exhibited very low thermal conductivity (22–24 mW/m.K) compared with conventional insulation materials on the market (30–50 mW/m.K). The thermal insulation properties of PE‐silica xerogels were increased by 45% and 49% compared with neat PE foam. Additionally, the compressive modulus and density of the PE‐xerogel foam was increased by the presence of the silica xerogel. These PE‐xerogel foams are believed to be excellent candidates for thermal insulation applications in terms of cost/performance.

Enhanced Foaming Behavior of Ultrahigh Molecular Weight Polyethylene by Blending Silicone Powder in Microcellular Foaming

Microcellular foaming with CO2 as the blowing agent is developed to prepare low‐density ultrahigh molecular weight polyethylene (UHMWPE) foams. To improve the foaming behavior of UHMWPE, silicone powder is used to modify UHMWPE by twin‐screw compounding. The silicone powder contents, foaming temperatures, and foaming pressures are varied to investigate their effect on the foaming behavior of UHMWPE in a one‐step microcellular foaming process. The results show that the addition of silicone powder leads to significantly improved foaming behavior of UHMWPE by simultaneously increasing the expansion ratio and refining cellular morphology. With the presence of silicone powder, UHMWPE with an expansion ratio up to 34‐fold is prepared, while the maximum expansion ratio of pure UHMWPE foam that can be achieved is only 15‐fold. Moreover, for the foams with the same expansion ratio, the presence of silicone powder leads to significantly refined cellular morphology. The improved melt flowability and accelerated crystallization by adding silicone powder are responsible for the significantly enhanced foaming ability of UHMWPE. The heterogeneous nucleation effect of silicone powder plays a critical role in refining the cellular morphology by promoting cell nucleation and reducing cell collapse.

Bacterial Adhesion on Prosthetic and Orthotic Material Surfaces

Prosthetic and orthotic parts, such as prosthetic socket and inner sides of orthoses, are often in contact with human skin, giving bacteria the capability to adhere and form biofilms on the materials of those parts which can further cause infections. The purpose of this study was to determine the extent of bacterial adhesion of Staphylococcus aureus and Staphylococcus epidermidis on twelve different prosthetic and orthotic material surfaces and how roughness, hydrophobicity, and surface charge of this materials affect the adhesion. The roughness, contact angle, zeta potential of material surfaces, and adhesion rate of Staphylococcus aureus and Staphylococcus epidermidis were measured on all twelve prosthetic and orthotic materials, i.e., poly(methyl methacrylate), thermoplastic elastomer, three types of ethylene polyvinyl acetates (pure, with low-density polyethylene and with silver nanoparticles), silicone, closed-cell polyethylene foams with and without nanoparticles, thermo and natural cork, and artificial and natural leather. The greatest degree of adhesion was measured on both closed-cell polyethylene foams, followed by artificial thermo cork and leather. The lowest adhesion extent was observed on ethylene-vinyl acetate. The bacterial adhesion extent increases with the increasing surface roughness. Smaller deviations of this rule are the result of the surface’s hydrophobicity and charge.

Hybrid constructed wetlands integrated with microbial fuel cells and reactive bed filter for wastewater treatment and bioelectricity generation.

The present study aimed to develop a pilot-scale integrated system composed of anaerobic biofilter (AF), a floating treatment wetland (FTW) unit, and a vertical flow constructed wetland coupled with a microbial fuel cell (CW-MFC) and a reactive bed filter (RBF) for simultaneously decentralized urban wastewater treatment and bioelectricity generation. The first treatment stage (AF) had 1450 L and two compartments: a settler and a second one filled with plastic conduits. The two CWs (1000 L each) were vegetated with mixed plant species, the first supported in a buoyant expanded polyethylene foam and the second (CW-MFC) filled with pebbles and gravel, whereas the RBF unit was filled with P adsorbent material (light expanded clay aggregate, or LECA) and sand. In the CW-MFC units, 4 pairs of electrode chambers were placed in different spacing. First, both cathode and anode electrodes were composed of graphite sticks and monitored as open circuit. Later, the cathode electrodes were replaced by granular activated carbon (GAC) and monitored as open and closed circuits. The combined system efficiently reduced COD (> 64.65%), BOD5 (81.95%), N-NH3 (93.17%), TP (86.93%), turbidity (94.3%), and total coliforms (removal of three log units). Concerning bioenergy, highest voltage values were obtained with GAC electrodes, reaching up to 557 mV (open circuit) and considerably lower voltage outputs with closed circuit (23.1 mV). Maximum power densities were obtained with 20 cm (0.325 mW/m2) and 30 cm (0.251 mW/m2). Besides the electrode superficial areas, the HRT and the water level may have influenced the voltage values, impacting DO and COD concentrations in the wastewater.