1-hexene/propene and 1,5-hexadiene/propene copolymers with different comonomer contents were produced through slurry and bulk polymerizations with high activity heterogeneous Ziegler-Natta catalysts. The density, thermal and mechanical properties and molecular structure of the final resins were characterized and showed that the copolymer density, characteristic transition temperatures, modulus, average molecular weights and crystallinity decreased as the comonomer content increased. Density effects were more pronounced when 1,5-hexadiene was used as the comonomer, while variations of the xylene soluble contents and of the characteristic transition temperatures were more pronounced in the presence of 1-hexene. These results can be explained in terms of the smaller regularity of the chain structure when comonomer molecules are incorporated. Particularly, NMR analyses indicated that both double bonds were incorporated when 1,5-hexadiene was the comonomer, leading to formation of cyclic structures. When the diene content increased, reticulation caused the production of insoluble polymer resins.
Propylene; hexane; hexadiene; copolymerization; Ziegler-Natta
