Ethylene was polymerized at 15,000–25,000 psi at 130–220°C. with free‐radical initiators in the presence of 0–10% of C14‐labeled propylene, butene‐1, and octene‐1. Polymer composition was determined by scintillation counting. Molecular weight measurements and polymer unsaturation as detected by infrared analysis gave independent estimates of chain transfer. It was concluded that the major reaction of all α‐olefins is copolymerization: chain transfer is a minor reaction. For all α‐olefins, r1 (where ethylene is monomer 1) is 3.2–3.3 uncorrected, or 3.4–3.6 corrected for chain transfer.
SynopsisMelt and solution viscosity properties of laboratory-prepared batch polymerized high pressure polyethylene have been found to correlate well with molecular weight. These polymers have narrow and nearly constant molecular weight distributions and contain essentially no long-chain branches. Short-chain branching was found to have little or no effect on the relationships. Polyethylene made in the same reactor having longchain branches had melt and solution viscosity properties which deviated seriously from these relationships. The deviations serve as a semiquantitative measure of long-chain branching. When long-chain branching is absent, the correlations serve as rapid methods of determining a,, for narrow-distribution polymers.
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