Home» EVA Foam Application
EVA Foam Application: Polymer has been one of the most important materials in human society, with its synthesis technology that had been developed since the early 19th century. Polymers are used in many applications, which influence every aspect of our lives. These edge advantages are due to polymers’ properties, such as light weight, easy processability, isolation and other unique properties. To pursue lower density, better isolation and other related properties, foaming technology has been applied into polymers since the 1930s.
Foam is a substance that entraps on the inside, well-dispersed bubbles/cells. Ethylene-vinyl acetate (EVA), also known as poly(ethylene-vinyl acetate) (PEVA), is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene.
EVA Foam Application
EVA Foam Application: is an elastomeric polymer that produces materials which are "rubber-like" in softness and flexibility. This is distinct from a thermoplastic, in that the material is cross-linked, and thus difficult to recycle. EVA has a distinctive vinegar-like odor and is competitive with rubber and vinyl products in many applications.
Running involves a series of heel-strikes on the ground. The midsole foams of running shoes, by absorbing energy, limit the peak impact force in the heel-strike. A finite element analysis (FEA) was made of the stress distribution in the heelpad and a running shoe midsole, using heelpad properties deduced from published force-deflection data, and measured foam properties. The heelpad has a lower initial shear modulus than the foam (100 vs. 1050 kPa), but a higher bulk modulus. The heelpad is more non-linear, with a higher Ogden strain energy function exponent than the foam (30 vs. 4). Measurements of plantar pressure distribution in running shoes confirmed the FEA. The peak plantar pressure increased on average by 100% after 500 km run. In compressive impact tests the foams, of density around 50 kg m(-3), have higher initial yield stresses than Ethylene Vinyl Acetate (EVA) foam of the same density. The conventional cross-linking method using an electron beam for polyolefin foams is highly efficient, but the drawbacks are: costly equipment, nonuniform crosslinking, uneven dispersion of chemical foaming agents and additives, and relatively low gel content, which affect physical properties of the foam. In this paper, low density polyethylene (LDPE) and ethylene vinyl acetate (EVA) were blended in an 80/20 ratio, and this noncrosslinked foam was exposed to various doses of electron beam irradiation in air. The foam was made using isobutane as the blowing agent.
Ethylene vinyl acetate (EVA) copolymer/multiwalled carbon nanotube (MWCNT) nanocomposite foams were prepared to improve tensile properties without sacrificing elongation at break and compression set of EVA foams by using melt compounding method, the most compatible with current industrial applications. Without any modification of MWCNT and special treatment, a significant improvement of the mechanical properties including elastic recovery was observed for the EVA/MWCNT foams with only 1 phr MWCNT. Improvement of tensile strength and modulus without sacrificing elongation at break and elastic recovery of EVA/MWCNT foams with 1 phr MWCNT may have significant implications toward the elastomeric applications.
EVA Foam Application: Energy absorption is an important characteristic of mouth guards worn to reduce injuries to the orofacial complex in contact sports. Mouth guards reduce impact forces to teeth and jaws as well as reduce lacerations to soft tissues. Concussion is also claimed to be reduced in contact sports in those wearing mouth guards. Better performance of mouth guards through improved energy absorption and reduction in transmitted forces can be observed when mouth guards are thicker or when there are air inclusions in the mouth guard material. However, thicker mouth guards result in impaired speech and reduced respiratory efficiency. Air inclusions have been shown to improve energy absorption, reduce transmitted forces, and eliminate rebound within impacts with no corresponding increase in the
Thickness of the mouthguard. Similar improvements in energy absorption from impacts have been shown with modern athletic shoes and “bubble wrap” packaging of fragile goods, both of which have air or gas inclusions in their construction. advantage of an EVA foam would be a reduction in the weight of the polymer in a mouth guard, which could lead to savings in manufacturing costs by reducing the amount of raw material used. Questions could arise, however, about the “mouldability”, durability, finishing requirements, and the consequent problems with oral bacteria if the foam inclusions of the mouthguard are breached. Most important, however, is whether foamed EVA would provide improved performance in mouthguards through greater energy absorption and reduced transmitted forces from impacts capable of breaking teeth.
They were all rearfoot strikers, did not use orthotics, and reported no lower extremity injury. The response of EVA foam midsoles could be modelled in compression and tension using a single modulus version of the Ogden hyperfoam material. The problems tackled were axisymmetric, with a vertical axis of rotational symmetry. The large deformation option is used. Meshing was chosen to maximise the computation stability; nevertheless most simulations became unstable at high deformations. The thin cell faces of EVA foam are not perfect for containing air. As the air provides a major shock cushioning mechanism in the foam, its loss reduces the midsole performance. There is a complex interaction between the heel-strike stress field in the foam and the gas diffusion from the foam. Although the gas diffusion can be modelled during uniform creep loading, it is not yet possible to consider all aspects of the stress-diffusion interaction.
Injuries caused by impact and contact are common sports such as football and rugby and more dangerous sports such as motor racing, boxing and skiing. Often, contact with other people can cause an athlete to become off balance, or change direction quickly; this causes damage to the connective tissue; powerful direct contact may also cause a joint to become displaced. Impact injuries usually include spinal injuries, ligament and tendon damage, fractures and head and spinal injuries. They also added that although injuries are a part and parcel of contact sports; measures if taken appropriately would reduce the likelihood of suffering from an injury. Protective clothing is often worn in more dangerous sports to protect the body from injury; this can often be seen in rugby and boxing. Some of the common injuries in most widely played sport activitie. Impact injuries can damage to the connective tissue, and cause superficial injuries such as cuts, bruises, and most fractures which can be treated with simple medication and will heal over time; however head and spinal injuries should be treated as emergency medical condition.