Studies on metallocene catalyzed copolymers of ethylene with 10- undecen- 1- ol

Ethylene was copolymerized with 10-undecen-1- ol in the presence of four different metallocene catalyst systems. The copolymers were characterized by differential scanning calorimeter (DSC) and by dynamic mechanical analysis (DMA). It was demonstrated that properties of the catalysts used affected the crystallization behaviour of the copolymers because the catalysts exhibited differences in conversions of the polar comonomer. The step crystallization technique using DSC provided useful information about the differences in comonomer incorporation in the chain. The formation of multiple peaks, based on differences in ethylene sequence length, is much weaker for the copolymers produced with a non- bridged metallocene, than for polymers produced with bridged catalysts. A study of the crystallization rates in nonisothermal experiments exhibited a small decrease in crystallization temperatures with increasing branching. The Hoffman-Weeks extrapolation of melting point vs crystallization temperature gave reasonable results for silylene-bridged copolymers. In DMA, study was made of the storage modulus as an indicator of stiffness and loss tangent as a measure of the effect of branching on the β-relaxations. The DMA measurements indicated a slight increase in the flexural modulus, or stiffness values, of the copolymers relative to the corresponding homopolymers. The damping curves did not show any peaks in the β-relaxation range, which indicates that the amount of short branching in the copolymers is negligible.