Compositional Heterogeneity of Copolymers

Molecular Structure of Styrene-Butadiene Copolymers

“…The width of this distribution can be varied considerably by changing the polymerization conditions. For instance, this distribution can be made quite narrow by polymerizing to low degree of conversion by the presence of a regulator (7). Still another type of heterogeneity arises from the distribution in molecular weights of the soluble molecules or the distribution in molecular weight between cross links in the gel portion of a rubber.…”

Butadiene-Styrene Resinous Copolymers

“…Comparatively little information on polymerization processes leading to high-styrene resins can be found in the scientific literature. MacLean, Morton, and Nichols (22) recently studied butadiene-styrene copolymers over the entire range of monomer composition. By the use of ierZ-hexadecyl mercaptan (hexanethiol) as modifier and isolation of polymer at low' conversion, products of relatively narrow range of molecular weight and relatively homogeneous as to comonomer composition of the chains w'ere obtained.…”