Development of the γ-crystal form in random copolymers of propylene and their analysis by dsc and x-ray methods
Abstract
Random copolymers of propylene with minor proportions of ethylene, butene and other comonomers develop γ-form crystallinity, mixed with α-form, on crystallisation from near the melting point. The proportion of γ-form increases with comonomer content. γ-form determinations, together with measurement of degrees of crystallinity by x-rays and melting point distributions by differential scanning calorimetry (dsc), after carefully controlled thermal treatment, can be used to characterize the chain distribution present. The effect of thermal history on the melt distribution observed by dsc and the ratio has been investigated in detail for one copolymer containing 6·5mol% ethylene, and the crystal morphology developed in this copolymer and fractions obtained by solvent extraction is discussed.
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High-pressure crystallization of iPP nanocomposites with montmorillonite and carbon nanotubes
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Effects of bulky 2,2′-substituents in dianhydrides on the microstructures and gas transport properties of thermally rearranged polybenzoxazoles
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