Graft‐polymerization of styrene on polyethylen single crystals

Abstract The graft polymerization of styrene through use of γ‐ray irradiation was carried out in vapour phase onto polyethylene single crystals, bulk films of polyethylene and paraffine crystals. It was found that the grafting yield for a given dosage was much less for polyethylene single crystals than for bulk films. The similar difference was also found between the pure paraffine (n‐tetracosane) and mixed paraffines, and these results were interpreted in the light of crystallinity. In order to characterize the polystyrene branches grafted onto the crystals, a new method based on chain transfer reaction was proposed for obtaining number of the grafted points and the length of the branches and was applied to the graft polymerization onto the polyethylene single crystals. The results were compared with those obtained for the graft polymerization onto paraffine crystals. In the latter case, molecular weight of the graft polymer obtained after extracting paraffines from the whole material could be obtained by assuming the copolymer as polystyrene homopolymer. In both of the cases the polymer branch was very long and the sites of grafting were very few. The crystallinities of the samples measured by a X‐ray diffraction method before and after the grafting showed that the grafting did not practically affect the original crystals. The surfaces of the grafted crystals were also examined by an electron microscope and the result implied that the reaction took place mainly on the surfaces of the crystals.