Crystal Structure of Poly(vinyl chloride) Single Crystals

Abstract

Poly(vinyl chloride) Single Crystals 235 of these lines are 1.9, 3.0, and -1.6 kcal per mol (±0.1) for PS-PVK, PMMA-MVK, and PPVK, respectively. Although the number of values of the quantum yield are too small for exact determination, the activation energies obtained are reasonable for the barriers to rotation about carbon-carbon bonds. ConclusionsAt room temperature and above, photochemical reactions may compete with very efficient radiationless processes. Below the glass transition temperature in PMMA-MVK, PS-PVK, and PPVK a temperature dependence exists for the Norrish type II reaction which can be attributed to the changes in the segment mobility of the polymeric molecule. In the case of PMMA-MVK and PS-MVK, higher type II quantum yields are obtained at higher temperatures in the glassy region. In the case of PPVK, the type II quantum yield decreases slightly with increas-ing temperature. The apparent activation energies obtained from the temperature dependences are 2-3 kcal/mol which are of the same order of magnitude as the energy barriers to rotation around C-C bonds.In the glass transition region the type II quantum yield increases greatly in all the polymers studied due to the great increase in polymer segment mobility which occurs at this temperature. Above the glass transition region, the type II quantum yields in all polymers studied seem to be constant and, within experimental error, equal to the quantum yields obtained in solution for the same polymer and/or analogous low molecular weight model compounds.Acknowledgment. The authors acknowledged the able assistance of Mr. B. McAneney in the molecular weight determinations, Dr. J. Slivinskas for the computer program calculating scission and cross-linking yields, and the National Research Council of Canada for generous financial support.

PVC Morphology

“…55 Each cell contains two PVC chains arranged in planar zig-zag conformation, with the c direction corresponding to two chemical repeat units. Natta and Corradini 68 have measured the unit-cell dimensions as follows: a=1.06 nm, b=0.54 nm and c=0.51 nm.…”

Pole figure analysis of poly(vinyl chloride) samples: A first approximation

“…6 The WAXD profile of commercial PVC samples presents only two clearly identifiable reflections of sufficient intensity: the 200 and the 110 reflections. All the others are either too broad and overlap extensively or they are too weak for practical purposes (i.e., the 020 reflection; see Refs.…”

Gelation crystallization of poly(vinyl chloride)

“…This was first obtained (in much lower definition) by Natta et aLI5 for prepared low-molecular-weight syndiotactic polymer (oriented after mixing with conventional atactic polymer) and later also identified in solution-grown crystals of syndiotactic material. 16 The unit cell is orthorhombic with a = 10.4 A, b = 5.3 A, and c = 5.1 8, (c being the chain direction). The reflections which served for the identification are listed in Table 11.…”