On the distribution of chlorine-atoms in chlorinated polyvinylchloride prepared by various methods

The monoclinic α-modification of drawn and undrawn 6-polyamide is transformed into the γ-structure by a treatment with aqueous iodine-alkalijodine solution. A detailed investigation of this structure by X-ray, IR-spectroscopy and calorimetry is reported. In contrast to the γ^*-structure, which arises by fast cooling from the melt or by cold-crystallization from the glassy state, the γ-modification is well ordered and may be further improved by annealing. The well ordered γ-structure is not hexagonal but has a monoclinic or orthorhombic elementary cell with a crystal density of 1.190 g/cm³. In contrast to the γ^*-structure the γ-modification has a high thermal stability and on heating is directly transformed into the melt. For samples with γ- and with γ^*-structure the same relation between heat of fusion and specific volume is found, giving a density of 1.090 g/cm³ for the amorphous regions, which agrees with the density of a completely amorphous sample. The heat of fusion of the γ-crystal is 51 cal/g. Certain differences in the X-ray diagrams and IR-spectra between samples with γ- and γ^*-structure are discussed.