Influence of Manufacturing Processes and Catalysts

At typical processing temperatures above 150 °C, chain cleavage occurs in polypropylene and branched or linear polyethylene with few unsaturated structures (MER increases), while branching and cross-linking dominates in polyethylenes with a high number of unsaturated structures (MER decreases). Fig. 4.39 (and Table 5.41). 

Ta b I e 4.4 Physical and chemical data of unstabilized CrOl- and Ti-cataiyzed PE-HD [38] 

Polyethylene MFR (g/10 min) MFRji/MFRj, (-) Yellow/ness Index (-) Tertiary H atoms per 1000 C Unsaturated bonds per 1000 C 

Ta b I e 4.5 Basic data for various polyethylene grades (catalytic amount of Ti/Mg- or CrO]-PE-LLD s ippm), 

Section 5.4 will present further investigations on the influence of catalysts and chemical structure on thermal-oxidative degradation in polyolefins in service. 

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Section 4.3.1.1 uses the example of polyolefins to show the influence of manufacturing processes and catalyst residues. 

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