Physicochemical study of crystals of ethylene-butadiene copolymers.

IR, differential scanning calorimetry, small-angle x-ray diffraction, bromination, and d. measurements of 3 butadiene-ethylene copolymer (I) [25068-01-3] crystals with butadiene (II)-(ethylene + II) molar ratios 2.3, 3.6, and 4.6 and trans double bond content <5% supported previous van der Waals potential energy calcns. that indicated I folds more easily than polyethylene if the trans double bond is located in the fold and that a high percentage of trans HC:CH groups is located on the crystal surfaces. The polymn. reaction leads to the formation of defects, consisting of 1 (b), 2 (bb), 3 (bbb) or more sequential mols. of II almost homogeneously distributed along a macromol. chain. The frequency of the type of defect depends on the II percentage; at very small I percentages, b defects prevail, while the addn. of more II causes bb defects.