Thermoplastic polyurethanes formulation, typical

Permanent Gases. Air can be whipped into liquid plastisol or used to froth liquid polyurethane formulations. In hot processing, where air could cause oxidative degradation, nitrogen alone is used typically, it is compressed into molten polymer during molding or extrusion to make thermoplastic structural foam. 

Polyurethane elastomers (some TUP, thermoplastic polyurethane) These terpolymers can be used uncured for most applications however, selected grades can be eross-linked to enhance properties. As a family these elastomers are tough and wear resistant. They have excellent chemical resistance and flexibility. They can have excellent clearity. Applieations include cable jackets. Automotive fascia, connectors, fittings, and many, many more. Ethylene-Propylene-Dlene Terpolymers (EPDM) These terpolymers typically contain a few percent of a diene such as hexadiene. This material is easy to fabricate and then is usually heat-treated at 125"C to 175 C to induce crbss-linking. The physical properties are much different after crosslinking. Commonly, they are heavily formulated for applications which include wire jacketing systems, automotive hoses, and roof sheeting. 

A typical example of the applications that hyphenated-TGA can be used for has been pub -fished by Pielichowski and Leszczynska [32 ]. They have shown how a combination of TGA and IR can be used to characterise the most abundant volatile products of polyoxymethy-lene/thermoplastic polyurethane blends and, having done so, have gone on to discuss the mechanism of their formation. Gupta et al[33] have shown how high resolution TGA-MS can be used to characterise the properties of a range of flame retardant bromobutyl rubber formulations. 

Thermoplastic elastomers that are formulated into hot-melt adhesives include polyurethane and block terpolymers, such as styrene-butadiene-styrene styrene-iso-prene-styrene and styrene-olefin-styrene, in which the olefin component is typically ethylene, propylene, and/or butylene. The saturation in the mid-segment of these terpolymers results in better UV and thermooxidative resistance than that of unsaturated butadiene and isoprene midsegments. 

Two-pack and moisture cured polyurethanes, which offer better chemical and solvent resistance, are increasingly being used. Two-pack epoxy (epoxy-amine) lacquers are also used but are not favoured for exterior use because of their poorer durability. Epoxy resins are notorious for their poor chalking characteristics. A typical example of a clear acrylic lacquer would be the following formulation recommended by the International Copper Research Association in the USA. It is listed in the Rohm Haas booklet on thermoplastic acrylics ... 

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