Entanglement molecular weight Thermoplastics

Hergenrother W.L. and Doshak J.M., Determination of entanglement molecular weight of thermoplastic elastomers by tensile retraction measurement, J. Appl. Polym. Sci., 40, 989, 1990. 

Polystyrene is an important commercial thermoplastic that has been described by Priddy [121]. Its entanglement molecular weight is aroimd 18,000 and for both structure-rheology studies and commercial applications, molecular weights much higher than this are of primary interest. Nearly all commercial polystyrene is atactic and is thus a transparent glass at temperatures below its Tg, which is 100 °C. New catalyst systems are able to produce isotactic and syndiotactic versions, but these have not found practical applications to date due to their brittleness. 

Tong J.D. and Jerome R., Dependence of the ultimate tensile strength of thermoplastic elastomers of the triblock type on the molecular weight between chain entanglements of the central block. Macromolecules, 33, 1479, 2000. 

Polybutene-1, PB-1, or polybut-l-ene is another stereospecific (isotactic) polyolefin polymer, discovered by Prof. Giulio Natta in 1954. It is a linear high molecular weight crystalline thermoplastic polymer, with low density (0.91). The ethyl side groups create entanglement, which provides for the very good creep resistance of this polymer, which also has an abrasion resistance comparable to UHMWPE, and an excellent resistance to chemicals and environmental stress-cracking. 

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