Improved chlorimated polyvinyl chloride

Chlorinated polyvinyl chloride in which at least 80% of the chlorinated units are 1,2-dichloroethylene units and in which the percentage of 1,2-dichloroethylene units arranged in sequences of four or more units exceeds significantly that to be expected from a random arrangement, which polymer is substantially non-crosslinked, may be prepared by chlorinating polyvinyl chloride suspended in a liquid halogenated hydrocarbon, or in an aqueous medium containing a liquid halogenated hydrocarbon, under irradiation from a high energy radiation source (wavelength shorter than 100 Angstruom units) at a mean irradiation dosage of 2000 to 35,000 rads. per hour. Preferred halogenated hydrocarbons are carbon tetrachloride and mixtures thereof with chloroform. Cross-linking may be prevented by excluding air, or by adding organotin compounds or tricresyl phosphate. The products may be blended with polyvinyl chloride to raise the softening point thereof. In examples, polyvinyl chloride is chlorinated in suspension in carbon tetrachloride, chloroform, mixtures of carbon tetrachloride and chloroform, and mixtures of water, hydrogen chloride and chloroform with and without carbon tetrachloride, while exposed to a cobalt 60 source. The products are compounded with polyvinyl chloride, dibasic lead phosphite, calcium stearate, wax, titanium dioxide and dioctyl phthalate.