Thermoplastic polyurethane polycaprolactone

Thermoplastic polyurethane elastomers have now been available for many years (and were described in the first edition of this book). The adipate polyester-based materials have outstanding abrasion and tear resistance as well as very good resistance to oils and oxidative degradation. The polyether-based materials are more noted for their resistance to hydrolysis and fungal attack. Rather specialised polymers based on polycaprolactone (Section 25.11) may be considered as premium grade materials with good all round properties. 

The major polymers with whieh PVC ean be alloyed are aerylonitrile-butadiene eopolymers, aerylonitrile-butadiene-styrene terpolymer, ethylene-vinylacetate copolymers, chlorinated polyethylene, chlorosulfonated polyethylene, thermoplastic polyurethanes, acrylics and methacrylics, and polycaprolactone. Table 18 lists the property enhancements achieved by blending these polymers with PVC. 

PROPERTIES OF THERMOPLASTIC POLYURETHANES BASED ON POLYCAPROLACTONE (POLYESTER) OF 2000 MOLECULAR WEIGHT... 

There are three main chemical classes of thermoplastic polyurethane (TPU) polyester, polyether, and a smaller class known as polycaprolactone [2]. 

Among the polyurethane, polyester, and polyamide thermoplastic elastomers, those with polyether-based elastomer segments have better hydrolytic stabihty and low temperature flexibiUty, whereas polyester-based analogues are tougher and have the best oil resistance (43). Polycaprolactones and aUphatic polycarbonates, two special types of polyesters, are used to produce premium-grade polyurethanes (12). 

Most thermoplastic elastomers are stable materials and decompose only slowly under normal processing conditions. If decomposition does occur, the products are usuaHy not particularly ha2ardous and should not present a problem if good ventilation is provided. Extra caution should be exercised when processing polyurethanes, especiaHy those containing polycaprolactone segments. In these cases the decomposition products may include isocyanates and caprolactam, both of which are potential carcinogens. 

Low profile plastics are added to reduce shrinkage during cure. They are normally thermoplastics that include polyvinyl acetates, polymethyl methacrylate, and copolymers with other acrylate, vinyl chloride-vinyl acetate copolymers, polyurethane, polystyrene, polycaprolactone, cellulose acetate butyrate, saturated polyester, and styrene butadiene copolymers. More details about the low profile additive (LPA) mechanism are published in the literature. ... 

THERMOPLASTIC (LINEAR) POLYURETHANE ELASTOMERS 247 Calculation of equivalent weights Polycaprolactone... 

Diphenylmethane 4,4 -diisocyanate (MDI) and 2,4 toluene-diisocyanate (TDI) are the most common diisocyanates used to produce polyurethane thermoplastic elastomers. The long-chain diols are usually polyesters [e.g., poly(ethylene adipate) glycol] or polyethers [e.g., poly(oxytetramethylene) glycol], Polycaprolactone glycol is used in premium products. 

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