X‐ray diffraction and infrared studies on annealed highly syndiotactic poly(vinyl chloride)

Abstract

X‐ray diffraction scans and infrared absorption spectra for the C‐CI stretching region were obtained for a highly syndiotactic poly(vinyl chloride) (PVC) sample made by the urea clathrate method. When the polymer was annealed at a series of increasing temperatures up to 180°C, x‐ray diffraction measurements showed that the crystallinity increases steadily with annealing temperature. Even at 50°C an increase above the original value of 63% was detectable and by 180°C it had reached 70% with a further increase to 78% after cooling to ambient temperature. There is a concurrent significant increase in the lateral crystallite dimensions. However, the infrared spectrum did not change, in agreement with the recent prediction of Moore and Krimm that there is no observable band splitting from interchain interaction in crystalline regions, thus indicating that these C‐CI bands cannot be used as a measure of crystallinity. The results from computer curve fitting of the spectra suggest that at least 85% of the polymer consists of long planar syndiotactic sequences and there is therefore substantial order along the chain direction. A mechanism for the increase in crystallinity on annealing, involving the lateral ordering of these regular chains, is discussed. Furthermore, as the temperature is raised some amorphous material is converted to a nematic phase, and this may crystallize during the subsequent cooling.

Vibrational assignments for the CCL stretching region of the Raman spectrum of poly(vinyl chloride)

“…These values agree quite well with the values of 0.10-0.20 generally found by x-ray studies for commercial PVCs and the value 0.63 found for well-annealed U-C PVC by Baker et a1. 16 They also agree well with the values estimated by Raman spectroscopy',' from the sum of the areas under the peaks at 608 and 636 cm-'; 0.11-0.22 and 0.64, respectively. Although this calculation is not rigorous, particularly because the value of N required is rather low and there is no direct evidence that the U-C PVC obeys Bernoullian statistics, it does suggest that the value of P, = 0.81 may be in the correct region for the U-C PVC.…”

Crystallization and Relaxation Behavior of Partially Disentangled Poly(vinyl chloride) Prepared from Large Molecule Solvent Dioctyl Phthalate

“… , assigned the band at 638 cm -1 , the carbon−chlorine stretching vibration of PVC, to long planar syndiotactic sequences. The intensity ratios of 638 and 690 cm -1 can be used to measure the content of planar syndiotactic units. Tabb and Koenig assigned the methylene deformation at 1427 cm -1 as a crystalline band and the ratio of intensities of the 1427 and 1435 cm -1 bands ( I 1427 cm -1 /I 1435 cm -1 ) as a relative measure of crystallinity.…”

Infrared study on the interaction of poly(vinyl chloride) and ketones. I. PVC‐MEK film system

“…PVC crystallinity was studied by many authors using x-ray diffraction and infrared spectrometry. [21][22][23][24][25][26] The existence of two types of crystals in PVC films was recently demonstrated by infrared and x-ray data. 26 This study was carried out with a variety of solvents and plasticizers and a relationship between gelation of PVC and crystallization was shown, with data that agreed with the results of Aiken et al I8 and Sabia and Eirich.…”