Ethylene-vinyl acetate – EVA  

Ethylene vinyl acetate (also known as EVA) is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene. 

It is a polymer that approaches elastomeric materials in softness and flexibility, yet can be processed like other thermoplastics. The material has good clarity and gloss, barrier properties, low-temperature toughness, stress-crack resistance, hot-melt adhesive water proof properties, and resistance to UV radiation. EVA has little or no odor and is competitive with rubber and vinyl products in many electrical applications. 

Above information cited from: http://en.wikipedia.org/wiki/Ethylene-Vinyl_Acetate ]]> http://www.bysources.net/twpress/?feed=rss2&p=2550 http://www.bysources.net/twpress/?p=2548 http://www.bysources.net/twpress/?p=2548#comments Mon, 02 Nov 2009 08:19:09 +0000 admin2 http://www.bysources.net/twpress/?p=2548 Nylon is a thermoplastic silky material, first used commercially in a nylon-bristled toothbrush (1938), followed more famously by women’s stockings (”nylons”; 1940). It is made of repeating units linked by peptide bonds (another name for amide bonds) and is frequently referred to as polyamide (PA). Nylon was the first commercially successful synthetic polymer. There are two common methods of making nylon for fiber applications. In one approach, molecules with an acid (COOH) group on each end are reacted with molecules containing amine (NH2) groups on each end. The resulting nylon is named on the basis of the number of carbon atoms separating the two acid groups and the two amines. These are formed into monomers of intermediatemolecular weight, which are then reacted to form long polymer chains. 

Nylon was intended to be a synthetic replacement for silk and substituted for it in many different products after silk became scarce during World War II. It replaced silk in military applications such as parachutes and flak vests, and was used in many types of vehicle tires. 

Above information cited from: http://en.wikipedia.org/wiki/Nylon

Thermoplastic Elastomers - TPE 

Thermoplastic elastomers (TPE), sometimes referred to as thermoplastic rubbers, are a class of copolymers or a physical mix of polymers (usually a plastic and a rubber) which consist of materials with both thermoplastic and elastomeric properties. While most elastomers are thermosets, thermoplastics are in contrast relatively easy to use in manufacturing, for example, by injection molding. Thermoplastic elastomers show both advantages typical of rubbery materials and plastic materials. The principal difference between thermoset elastomers and thermoplastic elastomers is the type of crosslinking bond in their structures. In fact, crosslinking is a critical structural factor which contributes to impart high elastic properties. The crosslink in thermoset polymers is a covalent bond created during the vulcanization process. On the other hand the crosslink in thermoplastic elastomer polymers is a weaker dipole or hydrogen bond or takes place in one of the phases of the material. 

Above information cited from:

http://en.wikipedia.org/wiki/Thermoplastic_elastomer ]]> http://www.bysources.net/twpress/?feed=rss2&p=2700 http://www.bysources.net/twpress/?p=2117 http://www.bysources.net/twpress/?p=2117#comments Wed, 05 Aug 2009 02:41:00 +0000 admin2 http://www.bysources.net/twpress/?p=2117

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