PERMEABILITY OF POLY(4-METHYLPENTENE-1) W ITH DIFFERENT DEGREES OF ISOTACTICITY

Poly(4-methylpentene-1) was prepared by bulk polymerization in the pre sence of a supported Ti-Mg catalyst, and the transport properties of t he polymer obtained were studied as a function of the stereo-regularit y of the material. Permeability coefficients, X-ray diffractograms, an d lifetime positron annihilation spectra were measured for samples wit h a content of isotactic fraction in the 58 - 98% range. It was shown that the variation of the degree of isotacticity of polymers does not change the permeability coefficients for different gases. No changes w ere observed in the degree of crystallinity, in the features of X-ray diffractograms, or in the parameters of lifetime spectra; these result s indicate that the free volume of poly(4-methylpenetene-1) is not sen sitive to its stereoregularity. The absence of significant dependences of permeability and other physicochemical properties on the tacticity of the polymer can be explained by the very loose packing of poly(4-m ethylpentene-1).