Non-plastics

An extremely wide range of surface finishes is possible which may not only simulate non-plastics materials but in addition produce novel effects. 

Texaco has conununicated the following acceptance criteria for its process (a.l). Depending on the design of the purification step after gasification, the process can deal well with up to 10% PVC in its feedstock. The tolerance to non-plastic materials like inorganics and paper is thought to be around 10%. Other acceptance criteria include ... 

Before MPW is fed into the process, a basic separation of the non-plastic fraction and size reduction is needed. This prepared feedstock is then introduced in the heated fluidised bed reactor which forms the core of the process. The reactor operates at approximately 500 °C in the absence of air. At this temperature, thermal cracking of the plastics occurs. The resulting hydrocarbons vapourise and leave the bed with the fluidising gas. Solid particles, mainly impurities formed from, e.g., stabilisers in plastics, as well as some coke formed in the process mainly accumulate in the bed. Another fraction is blown out with the hot gas and captured in a cyclone. 

The BASF process requires pretreatment. Plastics are separated from non-plastics, ground and agglomerated. The agglomerate is fed into the process. 

This figure is slightly superior to the worldwide consumption generally qnoted (150 million tonnes) probably becanse of distortions concerning the applications considered, with some non-plastics being included in the acconnting. 

The automotive industry favours sets of parts assembled by the plastic furnisher and including non-plastic elements such as metal components, electronics. .. This simplifies purchasing and on-line operations. For example, a seat module includes the frame, cushioning, slide system, position control device. .. 

Cardy RH, Lijinsky W, Hilderbrandt PW Neoplastic and non-plastic urinary bladder lesions induced in Fischer 344 rats and B6C3F1, hybrid mice by N-nitrosodiphenylamine. Ectotoxicol Environ Safety 3 29-35, 1979... 

The picture is less clear for molecular crystals when the molecules deviate strongly from a globular form. NMR data and tracer diffusion data are then often in disagreement. Diffusion profiles (In c, vs. distance) are found to be curved, which is usually attributed to additional heterogeneous and fast diffusion pathways. For plastic crystals, this could indicate that many of them possess a highly defective structure. Even for the aromatic ring molecule benzene, which forms a non-plastic crystal, one finds a D (NMR)/D (tracer) ratio on the order of 103. This cannot be understood unless one invokes other than bulk lattice mechanisms of diffusion. 

The lower the modulus of elasticity and the plasticity of a given material, the higher the deformation occurring in it. This phenomenon, especially for non-plastic materials, often hinders proper hardness estimation of a given object. Thus, efforts should be directed towards more precise... 

Mono- and polycrystalline natural and synthetic materials are not subject to plastic strain and have no independent slip system. Stress concentration occurs in them at.crack tips and at flaws in the material, affecting the maximum strength which originates from the chemical or physical cohesion forces present. Non-plastic materials (crystals, rocks, ceramics, glass) show brittle cracks—forming at very low plastic strain—usually originating from surface flaws. 

In some cases, conducting polymer-based ion-selective membranes can substitute the commonly used plasticized PVC-based ion-selective (liquid) membranes. However, there are fundamental differences between the two types of membranes. Conducting polymer membranes are most often non-plasticized and the charge is transported by both... 

In practice, ion plating is used mainly to deposit aluminium on non-plastics, but it is included here for the sake of completeness. 

The Plastics Directive foresees a QM value as a restriction criterion for ECH. As a consequence a pre-validated QM method was developed in the BCR project entitled Determination of the residual content of epichlorohydrin (ECH) in coatings . Similar to the BADGE discussion to justify determination of an area-related QM value, in this method it is stated that epichlorohydrin is mainly used in coatings on a non-plastic support. Therefore the amount of coating on a final article (e.g. coated cans) cannot be determined within an acceptable accuracy and, in consequence, the amount of residual epichlorohydrin should be measured and related to the area and given in mg/ dm2. The method was found to be appropriate for the quantitative determination of ECH at 1 pg per dm2 of coating. In general this allows for the detection of ECH at the level of 1 mg/kg polymer. 

Figure 3.1 Non-plastic (Newtonian) and plastic (non-Newtonian) melt flow behavior (courtesy of Plastics FALLO)...

The completion of harmonisation of rules for plastic food contact materials and articles is within sight. The finalisation of the positive list for authorised additives is likely to happen in 2008. In 2007 the Commission will, besides the Community list of authorised additives, publish a list of additives authorised at national level for which a valid application for EU authorisation has been made to EES A. Only these substances may be used until evaluation is finalised by EES A and a decision on authorisahon is taken by the European Commission. Another project in the plastics sector is the extension of the rules to multimaterial multilayer structures where the plastic layer is in contact with the food. At this moment only plastic materials which consist entirely of plastic are covered by the plastics Directive. These materials, when they are made up from layers of plastic, constitute only about 15% of the mutilayer market. Other multilayer materials such as beverage cartons, which consist of a food contact layer of plastic and aluminium and/or paper, are not yet covered by specific legislation. Extension of the plastics mles to these materials will have to take into consideration requirements for the non-plastic layers and establish mles for migration testing of these materials. 

Basic requirements for active and intelligent materials have been set in the Framework Regulation. However, some issues need further clarification. The main issues are the applicability of the requirements of the plastics directive to active and intelligent plastic materials, especially compliance with overall and specific migration limits, rules for non-plastic active and intelligent materials, risk assessment of active ingredients and if necessary conditions/restriction of their use, and mles on the efficacy of the materials in relation to instructions for their use and protection of the consumer. 

The time and temperature conditions that must be chosen to mimic contact with the food are regulated for plastics in Directives 82/711/EEC (basic rules), 93/8/EEC (basic rules, 1st amendment) and 97/48/EC (basic rules, 2nd amendment). Additional information can be found in CEN methods for overall migration (EN 1186-1 2002) and specific migrations (EN 13130-1 2005). In many cases national legislation also applies the use of such simulants, temperature and time conditions, to other, non-plastic, food contact materials. Eor ceramics a specific time/temperature/food simulant has been chosen 22 °C for 24 hours using 4% acidic acid as food simulant regardless of the real-life application, as described in Directives 84/500/EEC and 2005/ 31/EC. 

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). 

In the absence of specific legislation for the other (non-plastic) food contact materials used in take-away and snack food packaging then the plastics legislation is used as a guide, although limits are not taken as presumptive standards. Where possible, in the absence of specific migration limits (SMLs), levels found are related back to exposure restrictions such as tolerable daily intake (TDl) or acceptable daily intake (ADI). 

ASTM C285-88 (Re-approved 1994) Standard test method for sieve analysis of wet milled and dry milled porcelain enamel, for determination of the fineness of frit in wet-or dry-milled porcelain enamels and other ceramic coatings on metals by use of the number 200 or No 325 mesh, 212 ASTM C925-79 (Re-approved 1995) Standard test method for precision electroformed wet sieve analysis of non-plastic ceramic powders, for particle size distribution determination ofpulverized alumina and quartz for particle sizes from 45 pm to 5 pm by wet sieving, 212, 230... 

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