Random Butene-1/Ethylene Copolymers: Influence of Composition on the Three-Phase Structure.

A detailed analysis of the three-phase structure of random butene-1/ethylene copolymers was conducted by differential scanning calorimetry. The development of the crystalline, mobile amorphous, and rigid amorphous fractions was analyzed as a function of crystallization temperature and copolymer composition. It was found that, under the chosen experimental conditions, the rigid amorphous fraction (wRA) varies only slightly with crystallization temperature, but is affected by copolymer composition. The slight increase of wRA with ethylene content is discussed taking into account the recent literature data about an increased fold surface energy of Form II crystals of poly(butene-1) upon random copolymerization with ethylene. [ABSTRACT FROM AUTHOR]