Depending on whether they can be plasticized, elastomers can be categorized as either thermosetting or thermoplastic. Thermoplastic elastomers (TPE), which have been employed steadily more commercially since the 1990s, are rubber in the classic sense. Thermosetting elastomers are rubber. Rubber is treated using thermosetting equipment, whereas TPE is produced using thermoplastic equipment. These two forms of elastomers are processed in these two distinct methods.

A polymer substance known as TPE is described as having rubber-like flexibility at ambient temperature and having the ability to plasticize at high temperatures. Some of the qualities of thermoplastic rubber and thermoplastics are combined in this family of polymers. The TPE polymer chain’s fundamental structural characteristic is its ability to simultaneously join or graft various plastic segments (hard segments) and rubber segments (soft segments) with various chemical compositions.

The many varieties of TPE are as follows: styrene-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, and polyamide-based thermoplastic elastomers.

Elastomer made of styrene, a thermoplastic

The first studied thermoplastic elastomer is the styrenic block copolymer, which primarily includes SBS, hydrogenated SBS (SEBS), SIS, and hydrogenated SIS, among other materials. Its body is now the biggest and expanding thermoplastic elastomer in the world. Styrenic thermoplastic elastomers are particularly intriguing from an application standpoint due to their characteristics at room temperature that are comparable to vulcanized rubber as well as their remarkably high modulus of elasticity that does not change with relative molecular mass. Styrene-based thermoplastic elastomers are frequently utilized in wire, cable, waterproof coating, plastic modification, rubber elasticity, and other applications because to their high strength, softness, rubber elasticity, and little permanent deformation.

Elastomer made of polyurethane thermoplastic

Long-chain polyols (polyether or polyester) with an average molecular mass of 600–4000, chain extenders with a relative molecular mass of 61–400, and polyisocyanates are the main components of polyurethane thermoplastic elastomer (TPU). polymers with linear structure. While the chain extender and polyisocyanate make up the hard segment, the long-chain polyol (polyether or polyester) in the main chain of TPU macromolecules governs the soft segment’s low temperature performance, solvent resistance, and weather resistance. The resultant TPU can be either a soft elastomer or a brittle high-modulus plastic since the ratio of hard and soft segments can be varied widely.

TPU has been widely employed in a variety of industries, including footwear, healthcare, apparel, and defense supplies, but it has drawbacks, including poor aging resistance, a low coefficient of friction on wet surfaces, and a propensity for easy slippage.

Elastomer made with polyolefins

The major types of polyolefin thermoplastic elastomers (TPO) include blends, block copolymers, and graft copolymers. Two of the most common varieties of polyolefin thermoplastic elastomers are ethylene-octene copolymers (POE), which are produced by dynamic vulcanization, and thermoplastic dynamic vulcanizates (TPV), which are produced using metallocene catalysts.

POE

POE stands for polyolefin elastomers that are copolymerized with ethylene-olefin, such as ethylene-octene copolymer (EOC), ethylene-butene copolymer (EBC), and ethylene-hexene copolymer.

In general, POE refers to ethylene-octene copolymerized elastomers with an octene mass fraction of at least 20%. POE has unique mechanical, rheological, and age resistance qualities due to the specificity of its molecular structure. It has good low temperature toughness, high cost performance, and is gradually replacing ethylene propylene rubber in many situations. In addition to being used as a rubber, it can also be used as a thermoplastic elastomer, an impact modifier, and a toughening agent for plastics.

Since POE’s molecular structure is comparable to that of EPDM, it also has outstanding characteristics including resistance to aging, ozone, and chemical mediums. By crosslinking POE, the material’s heat resistance temperature is raised and its capacity for permanent deformation is diminished. Small, the primary mechanical characteristics have been substantially enhanced, including tensile strength and tear strength.
The three primary crosslinking techniques used in POE are the crosslinking with peroxide, the crosslinking with silane, and the crosslinking using an electron beam or -ray radiation. Additionally, POE has access to other crosslinking techniques including salt and photocrosslinking. Dicumyl peroxide DCP, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (bis 2,5), bis (tert-butylperoxyisopropyl) benzene BIPB, benzoyl peroxide (BPO), etc. are the most often used peroxide crosslinking agents.

TPV

Thermoplastic vulcanizate (TPV) is the name given to the thermoplastic elastomer produced via dynamic vulcanization. Unlike elastic block copolymers, which are a specialized form of TPE, TPVs are created from the synergy of elastomer/thermoplastic polymer blends and have superior qualities than simple blends.

Ethylene-propylene-diene rubber (EPDM) is a popular elastomer used in the production of TPV. Ethylene, propylene, and non-conjugated diene are the main components of EPDM. The double bond in a diene is reactive. It can be produced by the action of a vulcanizing agent. EPDM with plenty of crosslinking. Although EPDM has strong mechanical, thermal, and weather resistance, it has weak hardness and processability, which restricts its growth.

Dynamic vulcanization technique is essential for creating TPV. One of the developments in this technology is the ability to create new products by combining current polymers using low-cost existing processing techniques. Nylon/EPDM type TPV, PP/EPDM type TPV, nylon/nitrile rubber type TPV, etc. are a few examples.

04 Thermoplastic elastomer made of polyamide

TPAE is made up of a non-crystalline soft segment (polyester or polyether) and a high melting point crystalline hard section (polyamide). The kind of hard segment used and the size of the two blocks affect how well it performs. TPAE provides outstanding toughness, chemical resistance, wear resistance, and sound attenuation thanks to the presence of hard segment polyamide. Their mechanical, thermal, and chemical characteristics may be altered across a large range by choosing and managing the class of blocks.

Both the dibasic acid approach and the isocyanate method can be used to synthesize TPAE, depending on the raw materials needed. By esterifying carboxyl-terminated aliphatic polyamide blocks with hydroxyl-terminated polyether diols, TPAE is made using the dibasic acid technique. Aliphatic polyester, polyether, or polycarbonate serve as the soft segment in the isocyanate process while semi-aromatic amide serves as the hard segment.