Lubricants plasticiser migration

As a moulding material, PVC was considered as an alternative to ABS for telephone housings and its applications included selector mechanism bank separators (Fig. 8.14). In selector mechanism bank separators it suffered from ageing, plasticiser migration and, with particular relevance to the selector application, was chemically degraded by the zinc content of finely divided brass or nickel silver wear debris. The problem was minimised by attention to material grade since the mechanism was found to relate to the lubricant and stabiliser contents of the plastic. 

Printing on vinyl surfaces can be problematic due to the influence of the formulation ingredients, particularly heat stabilisers and lubricants, on print adhesion. Spectroscopic analysis of PVC-P films has identified the formation of a barium zinc stearate complex which formed in the PVC matrix and migrated to the surface (207). Polymeric plasticisers have been developed to increase the surface energy, and so improve print adhesion. The incorporation of stearic acid had a surface energy reducing effect when used with the polymeric plasticiser (193). 

But plastics contain low molecular compounds such as oligomers and sometimes monomers, and additives such as plasticisers, lubricants, stabilisers and antioxidants, which are absolutely necessary either for the processing or the stability of the final polymeric materials. The drawback of using these is the potential migration of these additives from the package into the packed material. This is a problem of major interest where food or drugs are concerned. 

Areas in which X-ray photoelectron spectroscopy might be expected to perform best are the detection of surface effects (e.g. blooming), surface active additives (e.g. release and slip agents, lubricants, surfactants, etc.), rapidly migrating additives (e.g. plasticisers), or thin-film contaminants. XPS detection limits for additives (0.5 vol.%) are unfavourable for... 

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