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Stereoregular poly(vinyl chloride)(PVC)was prepared by solid state polymerization.Its solubility into organic solvents and the thermal properties were studied in comparison with those of ordinary free radically prepared sample.Urea canal PVC was obtained in a form of white powder,which was thermally unstable as evidenced by easy discoloration in the powder state heating up to 80oC to be pale purple.In contract,free radical PVC didn't causediscoloration in the solid state under the same conditions.Easy discoloration of urea canal PVC is probably due to the absence of termination reaction,and the insolubility into organic solvents is due to the stiffness of polymer chain.An elimination reaction was studied by FT-IR and 13C NMR spectra were measured.The elimination reaction was more rapid in free radical PVC(in solution)than in urea canal one(in suspension).The resulting poyene structure-(CH=CH)n-was essentially trans-form not cis-one.