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Influence of annealing, thermal history, and solvent treatments on the degree of crystallinity and glass transition temperature of normal and low temperature-polymerized PVC

1981; Taylor & Francis; Volume: 19; Issue: 2 Linguagem: Inglês

10.1080/00222348108223937

1525-609X

Paramjit Singh, J. Lyngaae-Jøsrgensen,

Polymer Nanocomposites and Properties

Abstract The influence of annealing, various thermal histories, and solvent treatments on the crystallinity, glass transition temperature, and shear modulus-temperature behavior has been studied in thin films of normal- and low-temperature-polymerized poly(vinyl chloride). It was found that annealing and solvent treatments could raise the crystallinity index of normal PVC by as much as 20%, while the low temperature PVC films were almost unaffected. Heating for short times (8–10 sec) at high temperatures (400–500ďC) had no significant effect. The glass transition temperature of films of neither resin was influenced by thermal treatments above Tg. A drop in Tg was observed between the first and the subsequent runs in case of low-temperature PVC powder, but wide-angle x-ray diffraction studies indicated that the crystallinity either was unaffected or increased as a result of heat treatment. The shear modulus-temperature curve for low-temperature PVC exhibited a very broad transition, and in case of the annealed films the curve was found to lie below that for the normal PVC until the point of sharp fall in the later curve beyond which it crossed over and then stayed above the normal PVC curve.