Thermally induced conformational changes in poly(vinyl chloride)

Abstract

Fourier transform infrared spectroscopy has been used for the detection of thermally induced conformational changes in atactic poly(vinyl chloride) (PVC). Difference spectra emphasize changes in the distribution of gauche defects in the chains as functions of temperature and annealing. Specific bands in the ν(CCl) and δ(CH2) regions varied with inverse temperature, allowing a calculation of the activation energies of the rotamer species. Conformational changes were also detected in quenched PVC films as a result of annealing below the glass transition temperature, Tg.

FTIR studies of conformational energies of poly(acrylic acid) in cast films

“…Substitution of these relations into the van't Hoff times controlling a structural relaxation. 11,12,14,15 Then the equilibrium constant, K is defined by relation yields Figure 3. Difference spectra of PAA obtained at 10ЊC intervals from 50 to 110ЊC.…”

“…A similar apture stability of better than {0.1ЊC. Calculation of the spectra was performed by Grams/386 (Gaproach was followed to study conformational changes of poly(vinyl chloride), 11,12 poly(methyl lactic Industries Co.) methacrylate) (PMMA), 13,14 and of deuterated PMMA 15 of various tacticity, and the conformational energies acquired were confronted with the…”

The influence of additives on crystallization of polyvinyl chloride

“…There is a marked peak at about 60 ℃. This peak is probably due to that PVC chains have not enough time to relax in quenching process, when annealed below the glass transition temperature, these chains relax and make the hole concentration in amorphous regions decrease [21] .…”

Irreversibility of stretching-induced local conformational changes as verified through an FTIR dichroism study for PVC

“…On the contrary at temperatures above 120°C the occurrence of a decrease of extended structures and a corresponding increase in less stable conformers was proposed. 10 Also, some attempts have been made in our laboratory especially to give further support for the GTTG À TT conformation-based mechanisms of a few chemical 1±3 and physical 5±9 behaviours of PVC. The detailed assignments of the carbon-chlorine stretching vibrations in the infrared spectrum of PVC have been made by several authors.…”