Plastics compliance testing

With this increased emphasis on testing foods, activity in searching for alternative simulants has diminished. This is to be welcomed. The use of food simulants in compliance testing for the general case (see Chapter 15) is still important. But the quest for alternatives that mimic simulants that in turn are intended to mimic foodstuffs represents a cul-de-sac. A simulant has to resemble a food in its interaction with the food contact material. It is clearly the case that different simulants are needed for different foods and for different materials, paper versus ceramics versus plastics for example. And maybe even different simulants could be needed for different classes of plastics and different types of substances. But if simulants have to be fine-tuned and tailored for individual applications then they lose much of their utility. 

Testing plastics materials for compliance with EU directives... 

This article outlines the food contact legislation in the UK that applies to plastic articles and materials that come into contact with food. Key requirements are that materials must not transfer chemicals to food in quantities that cause a hazard to human health, or cause the food to become tainted with a strange taste or odour. The regulations also set out testing conditions that enable compliance with the requirements to be demonstrated. 

These guidelines were originally developed for testing the suitability of plastics used in medical devices that may come into contact with bodily fluids, but they have been extended to adhesives as well. Generally, products are tested by an independent laboratory. The results are typically provided to device or adhesive manufacturers in the form of certifications of compliance on an as-requested basis. Meeting these standards verifies that the successfully tested products are nontoxic and biologically inert in the cured state. 

To support the analyst in applying such controls, CEN (the European Standardisation Commission) has in TC 194 adopted and validated analytical methods for the determination of the overall migration and the migration of some specific substances. These methods are intended to be applied for testing plashc materials and articles. At national level, e.g., in The Netherlands, the methods and simulants may also be used to demonstrate compliance with national regulation of non-plastic or multilayer materials composed of plastics and non-plastics (e.g. plastic on paper, coating on metal). 

Typical materials analysed using this technique include glass, uranium oxides, steel, platinum, geological samples, ceramic materials and plastics (Figure 7.21). Excellent information is obtained where surface composition is important, e.g. catalysts, presence of toxic elements, surface analysis in the application of adhesives, etc. It can be used as a quick qualitative test for the analysis of semiconductor components as specified as part of WEEE and RoHS compliance. 

Non-primary components such as cartons can also employ gauges, although obviously the type of gauge will be somewhat different, e.g. a transparent plastic line drawing of the carton profile, creases and scoring will show specification compliance if simply laid over the test carton. They can also show positional variation of identification and register code bars. 

Plastic materials are quite effective in controlling corrosion in industrial processing and storage. In a variety of applications, plastics are the only acceptable choice for process surfaces because of their chemical inertness. In each case, plastics must be qualified by testing to insure adequate corrosion protection and compliance with ever more stringent environmental and safety regulations. 

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