High-density polyethylene stabilisers

An additive system was developed for poly(vinyl chloride) for medical applications. The additives include primary stabilisers (Ca-Zn stearate and Zn stearate), secondary stabilisers (epoxides) and lubricants (ethylene bisamide and high density polyethylene), to improve melt processing and heat stability. The use of the stabilisers resulted in reduced equipment down-time, increased the level of recycled material which could be incorporated, and enhanced the product characteristics, including colour, clarity, blush, aqueous extractables and particle generation. 5 refs. 

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). 

Mariani P, Carianni G, Balducci D, Roccasal-vo S, La Mantia FP. Melt stabilisation of high-density film-grade polyethylene. Macromol Symp 2001 176 73-82. [1st International Conference on Polymer Modification, Degradation and Stabilisation, 2000]. 

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