INSIGHT INTO Polyethylene

To get a better insight into the chlorination reaction, we wanted to avoid a heterogeneous process. Instead of polyethylene or polypropylene, we used polyisobutene, which is soluble in carbon tetrachloride, as are its chlorination products. In addition, we were interested in the structure and properties of the chlorinated products, especially in comparison with polyvinyl chloride (PVC) and vinyl chloride/isobutene (VC/IB) copolymers. 

The recombination between two alkyl radicals is believed to be the main source of radiation-induced crosslinks in polyethylene [21], so that it is important to study the mechanism for formation and reaction of the alkyl radical. We have applied the ESE method to elucidate the paramagnetic relaxation mechanism and the spatial distribution of the alkyl radical, in order to get further insight into the radiation-chemical reactions of polyethylene resulting in the formation of crosslinks. 

Since these first calculations, a variety of theoretical methods have been studied and applied to ideal chains of polyethylene and other polymers. The books by Ladik (1988) and Andre et al. (1991) describe theoretical methods employed, and the literature published prior to 1990. While these calculations provided some insights into the microscopic origins of the electronic properties of the polymers modelled, the correlation of predicted properties, e.g. the band gap and bandwidths, with experimental data was poor. The quality of the experimental data was also variable. 

In this work, the ESC resistance of two high-density polyethylenes obtained using different catalytic systems was compared at varying detergent concentration, in order to obtain some insights into the role played by the molecular structure of the material. 

In principle, the computational approach to the kinetics of the complex photooxidation process can give meaningful insight into the effects of outdoor weathering of hydrocarbon polymers. For clear amorphous linear polyethylene, the model suggests that the optimum stabilizer would be a molecularly dispersed additive in very low concentration which could trap peroxy radicals. An additive which decomposes hydroperoxides would also be effective but would require higher concentrations. The useful lifetime of unstabilized polyethylene is predicted to vary from a few months in hot weather (100°F) to almost two years in cool weather (45°F), which correlates well with experimental results and general experience. 

Acrylics are unsymmetrically substituted polyethylenes which are widely used and of technological importance. The high mass range spectra of the acrylics provide valuable insight into the SIMS fragmentation process, so they will be treated as a separate category. Both methacrylates and acrylates will be discussed. 

Understanding the polymerization process used to make a particular plastic gives insight into the nature of the plastic. For example, plastics made via condensation polymerization, in which water is released, can degrade when exposed to water at high temperature. Polyesters such as polyethylene terephthalate (PET)... 

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