Specifications for Waste Plastic

Additional information on markets for recycled plastics is available in the Illinois Recycled Materials Market Directory (ILENR/RR-87/01), and the accompanying update, available from the Illinois Department of Energy and Natural Resources, Office of Solid Waste and Renewable Resources, Springfield, Illinois. The State of Wisconsin Depanment of Natural Resources, Bureau of Solid Waste Management (Madison, Wl.) also makes available a Wisconsin State Plastic Recycling Directory. 

One method of addressing plastic contamination in general is R link recycle product prices to product quality on a commonly accepted standardized system such as The American Society for Testing Materials (ASTM). The ASTM D-20 Committee addresses plastic recycling and degradable plastics. There are four draft standards regarding waste plastic contamination and recycling  

ASTM X-95-1-3 Guide for Development of Standards Relating to the Proper Use of Recycled Plastics (1/15/89) 

ASTM X-95-2-6 Standard Practice for Generic Making of Plastic Products (4/15/90) 

ASTM X-12-73 Proposed Standard Spcxtification for Polyethylene Plastics Molding and Extrusion (7/20/90) 

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Experimental and theoretical studies [32, 33, 35, 37] showed that, for different plastic waste feeds (PE, PP, PET, their mixtures) and under a fixed reactor temperature, the time of occurrence of defluidization for a bed of a given material is linearly related to the value of the ratio between the bed solids hold-up and the polymer feed rate. The latter is a key parameter of the process. Diagrams in Figure 16.6 summarize all the data obtained in these experiments under different operating conditions and report the linear relationships that fit the data very well for the specific temperature and plastic waste feeding. 

Unused reactants can be recycled and off-specification product reprocessed. Integrated processes can be selected the waste from one process becoming the raw material for another. For example, the otherwise waste hydrogen chloride produced in a chlorination process can be used for chlorination using a different reaction, as in the balanced, chlorination-oxyhydrochlorination process for vinyl chloride production. It may be possible to sell waste to other companies, for use as raw material in their manufacturing processes for example, the use of off-specification and recycled plastics in the production of lower grade products, such as the ubiquitous black plastic bucket. 

Some of the common reasons for size reduction are to liberate a desired component for subsequent separation, as in separating ores from gangue to prepare the material for subsequent chemical reaction, i.e., by enlarging the specific surface as in cement manufacture to meet a size requirement for the quality of the end product, as in fillers or pigments for paints, plastics, agricultural chemicals, etc. and to prepare wastes for recycling. 

The tenn size reduction is applied to all the ways in which particles of solids are cut or broken into smaller pieces. Throughout the process industries solids are reduced by different methods for different purposes. Chunks of crude ore arc crushed to workable size synthetic chemicals are ground into powder sheets of plastic are cut into tiny cubes or diamonds. Commercial products must often meet stringent specifications regarding the size and sometimes the shape of the particles they contain. Reducing the particle size also increases the reactivity of solids it permits separation of unwanted ingredients by mechanical methods it reduces the bulk of fibrous materials for easier handling and for waste disposal. 

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