A certain amount of ordering has been found in “noncrystalline” synthetic rubbers, which were studied by the use of the technique of cooling the raw polymer before it is elongated and freezing it immediately after stretching to prevent relaxation. Polybutadiene and polydimethylbutadiene, whose monomer units were structurally symmetrical, displayed the greatest degree of ordering. The presence of a high percentage of 1,2-units in sodium-polymerized butadiene destroyed almost all of the ordering observed in the emulsion polymer. GR-S and emulsion polybutadiene showed the presence of small amounts of crystallites, presumably of 1,4-addition polybutadiene, probably the trans-form. Polydimethylbutadiene showed the presence of crystallites presumably of 1,4-addition in the cis-form. The intermolecular distance between the extended chains increased with increasing amounts of side groups. The departure of the Bragg angle spacing of the amorphous halo from the corresponding quantity for the liquid monomer increased with increasing amounts of side groups.
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