EVA | Foamed - Thermoplastic polymers, elastomers and additives

The EVA copolymer, which has a low proportion of VA (approximately up to 4%), can be referred to as polyethylene modified with vinyl acetate. It is a copolymer and is processed as a thermoplastic material, just like low density polyethylene. It has some of the properties of a low density polyethylene. Generally considered a non-toxic material.

The EVA copolymer, which has an average VA ratio (about 4 to 30%), is termed a thermoplastic ethylene-vinyl acetate copolymer and is a thermoplastic elastomer material. It is not vulcanized, but it has some of the properties of a rubber or plasticized polyvinyl chloride, particularly at the upper end of the range. They can be filled and both filled and unfilled materials have good properties at low temperatures and are resistant.

When it comes to a finished look, the overall appearance of a compression molded EVA foam (vacuumform / thermoformed) part can not be compared to that after an injection part of molded foam. The density increase and perfect "mold" finish of an injection mold, produces a part with a much superior aesthetics. Because the foam used for compression molded parts is outsourced, the quality of the foam is also likely to be variable, affecting the aesthetics of the final part. On the other hand, because injection molded foam is manufactured in the company with foam and part at the same time, the quality is always constant. Specific variables that affect the quality of compression parts, but not injection parts, are:

Plastic foams have many advantages, such as: weight, insulation capacities (sound and heat), energy absorption (impact, impact and vibration), buoyancy, and elastic properties in certain cases. Plastic foams are polymers containing dispersed cells throughout the polymer matrix. Polymer foam can be viewed from different perspectives, such as product dimension, foam density, cell size, cell density, foam morphology and foam properties. Foamed plastics have a wide density range of approximately 1.6 kg / m3 to more than 960 kg / m3. Depending on the average cell size and cell density, they can be divided into three main categories:

Compression of molded EVA foam parts will almost always cost you less than molded foam injection. Not only are the tools and equipment less expensive but the parts as well. Because compression molding uses bread bags, they are often chosen (cheap) low density foams. This results in inferior quality products that are excellent for a gift or other temporary product. Foam injection molded products, while more expensive, are attractive, with lasting value.

Those with low content of vinyl acetate (3 to 20% by weight) are used in the plastics market. In the toy industry they are used to make car wheels, puzzles, flexible early childhood toys, etc. Other applications are the manufacture of shoe soles, beach sandals, life vests, fenders, packaging, gaskets, tubes, cable covers, bags and deep-frozen containers.

Plastic materials are naturally good for long-term use. EVA foam can be added to natural rubber and EPDM material that can not only improve its strength, but also its durability and make it subject to long-term use. The rubber materials are durable but they are so heavy that sometimes they are not practical and portable to use. Compared to rubber materials, EVA foam is much more portable and easy to move. After adding a tough additive for its production, EVA foam can actually perform better than rubber materials, it also offers long-term durability.

EVA materials are widely used for marine products and applications. The EVA foam has a strong buoyancy in the closed cell structure. They are excellent in water resistance. You should also know that low and medium density EVA foam materials are lightweight and portable. These advantages make them quite suitable and outstanding for marine products. You can easily see EVA foam materials for water floats, boat cushion mats, swim boards and even as foam pieces in life jackets.

EVA foam is a closed cell foam material. They are naturally good at insulation. Also other closed cell foam materials do have better insulation abilities than open cell foam. For production, EVA foam materials need to go through vulcanization procedure where they are formed with a cross-linked also closed cell molecular structures. The insulation abilities of EVA foam includes heat and thermal insulation.The can resist temperature from minus 30 degree centigrade to 80 degree centigrade. Besides, we can also put ire retardant additives and anti -static agents to enrich the insulation performance of EVA foam materials.

As mentioned above, when the EVA foam sheet is produced, we can place natural rubber elements and other elastic additives. In this way, we can formulate highly resistant EVA foam materials once we use those resistant elements. Sometimes, the customer requires high strength EVA foam and is actually the mixture of EVA foam and rubber. Highly elastic EVA foam materials can be widely used to improve the cushioning and durability of products. Some foam products can see highly resistant EVA foam materials, such as squeegee blades, foam seals, foam gaskets, seat cushions, etc.