Question

Why random copolymers have a single glass transition temperature?

Answer 1

Glass transition temperatures Tg for a wide variety of (A-random-B) copolymers have been determined by means of d.s.c., with A, B = methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, t-butyl acrylate, 2-ethyl hexylacrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, t-butyl methacrylate, acrylonitrile, styrene and vinyl chloride, respectively. The composition of the AB copolymers was varied from 0 to 100% (w/w) in steps of 20%, thus yielding a data set of more than 400 Tg values. All types of Tg versus composition dependence were recovered, resulting in linear, convex, concave and sigmoidal shapes. In most cases, a satisfying description of the data was achieved via a one-parameter fit according to the Gordon-Taylor equation.

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