Polymethylene and the structure of polyethylene: Study of short-chain branching, its nature and effects

摘要: Model compounds in the form of polymethylenes, linear and branched, have been prepared used to develop methods measuring numbers lengths branches polymethylene. The polymethylenes for calibration work contain deuterated butyl branches; present polymers hava established by two independent methods: direct assay deuterium mass spectrometric analysis irradiation products. Using this series a new infrared tecnique has calibrated absolutely measure total number methyl group also specifically. technique is compensation method, using solid specimens double-beam spectrometer, which compensating material (linear polymethylene) devoid structural features, namely branches, be measured. same reference samples ethyl-branched (Hydropol), method estimating ethyl branch concentration developed. A study gaseous products butyl-branched anlysis, shown extent might provide quantitative means identifying such polymers; it greatly strengthened evidence earlier workers that low density primarily branches. conclusion, more terms, drawn from an various polymethylene-specimens: practically all observed can accounted as ethyls butyls ratio approximately 2:1. Some high polyethylenes few appear groups. effects on degree crystallinity, crystalline melting point, density, rate oxidation, dynamic mechanical properties are illustrated discussed. status theories concerning mechanism formation short side chanis polymethylene considered.