Physical properties of some ethylene polymers

Various physical properties of 43 experimental ethylene-1-olefin copolymers and ethylene homopolymers produced by the Ziegler route were subjected to a statistical analysis. Correlations obtained indicate that the density of these polymers is a function almost solely of the number of branches introduced by the comonomer, regardless of their length. Similarly, tensile modulus and yield strength are shown to depend primarily on density, and to be independent of branch length. Physical properties of commercial resins produced by both low- and high-pressure processes are shown to follow the same relationships. Examination of homopolymers of widely different melt indexes indicates that vinyl unsaturation is not a reliable measure of number average molecular weight.