Abstract

AbstractQuantitative thin‐section electron microscope studies were made on compositional fractions of ethylene copolymers crystallized under several extreme conditions. The co‐units chosen were such that the chains contained either ethyl, hexyl, or acetate side groups. Certain general features are independent of the chemical nature of the co‐unit. It was found that up to about 2 mol % co‐unit content lamellae are observed in all copolymers which were slowly cooled from the melt. The lateral dimensions of lamellae are not as large as in corresponding homopolymers and the lamellae are segmented. As the branch content increases the lamellae become shorter and eventually degrade into small crystallites. Within this broad outline of behavior, differences between the copolymer types are discerned and discussed. By comparison with the Raman LAM it is shown that quantitative values for the crystallite size distribution are obtained by the electron microscopy method used. Furthermore, when the specimen consisted of well‐ordered lamellar stacks the degree of crystallinity obtained from the electron micrographs was in quantitative agreement with the enthalpy of fusion.

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