✍ Scribed by Jozef Bicerano; Robert L. Sammler; Craig J. Carriere; Jerry T. Seitz
No coin nor oath required. For personal study only.
The empirical form for the dependence, Tg(n) = Tg(co) (1 + a / n ) , of the glass transition temperature Tg on the average number n of repeat units between crosslinks, is generalized for randomly crosslinked high polymers. The new form, TJn)
is based on a correlation study of data for 77 samples of 10 different sets of resins. The fitting parameter a is resolved into composition-dependent N,,, and composition-independent c terms. N,,, summarizes the average number of rotational degrees of freedom per repeat unit, and is estimated in a straightforward manner from the structure and mol fraction of each repeat unit. The value of c is found from data analysis to be 5 f 2. The results of this work are consistent with expectations based on the entropy theory of glasses, and provide improved understanding and predictive ability for the properties of crosslinked polymers.
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A new quantitative model is proposed to correlate glass transition temperatures with bond radii-based structural parameters for poly( p-alkyl styrenes), polyolefins, poly(alkyl methacrylates), and poly(alkyl acrylates). The model provides a consistent prediction of the glass transition temperatures
## Abstract 4‐Chloromethyl styrene was copolymerized with various molar ratio of methyl methacrylate or ethyl methacrylate by solution free radical polymerization method, at 70 ± 1°C using α,α′‐azobis(isobutyronitrile) as an initiator. Then, very highly sterically hindered tris(trimethylsilyl)methy