HDPE, additives Stabilisers

Oligomeric hindered amine light stabilisers, such as Tinuvin 622 and Chimassorb 944, resist satisfactory analysis by conventional HPLC and have required direct UV spectroscopic analysis of a polyolefin extract [596], PyGC of an extract [618,648], or SEC of an extract [649]. Freitag et al. [616] determined Tinuvin 622 in LDPE, HDPE and PP by saponification of the polymer dissolution in hot toluene via addition of an... 

Oxidative degradation and the importance of antioxidant additives have already been discussed in detail in Sect. 5.2.2. T q)ically, phosphite and a hindered phenol are used as the main components of the antioxidant package for most of the HDPE geomembranes available on the market. Normally, carbon black is added as UV stabiliser. The concentration of the antioxidant components is t3 ically in the range of a few thousand ppm (mg/kg). Depletion of these antioxidants was identified as the relevant... 

Crompton [59] has described a simple direct thin-layer method for the determination of UV 531 ultraviolet stabiliser in hot toluene extracts of HDPE. Interference was encountered from a number of additives, namely, dilauryl thiodipropionate, lonox 330, lonol CP, Topanol CA, Santonox R and Polygard. 

In this connection, O Brien and co-workers [13,14] carried out detailed studies of the use of the mathematical models for the prediction of migration of additives from food contact polymers and compared these predictions with experimental data. In their first paper [13] experimental migration data was obtained and used to evaluate two Fickian-based models for predicting the migration of four additives from high-density polyethylene (HDPE) into olive oil. Additives were a benzophenone UV stabiliser (2-hydroxy-4-N-octyloxy benzophenone), an antioxidant and a benzothiazole stabiliser, a colorant carrier (adipic acid, bis(2-ethylhexyl) ester, a propionate antioxidant (octadecyl-3-(3,5-di-ter -butyl-4-hydroxyphenyl)propionate) and a benzotriazole UV stabiliser (2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole). 

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