Plastic containers separate process

Recycling polymers is one way to minimize the disposal problem, but not much recycling occurs at present. Only about 25% of the plastic made in the United States is recycled each year, compared with 55% of the aluminum and 40% of the paper. A major obstacle to recycling plastics is the great variation in the composition of polymeric material. Polyethylene and polystyrene have different properties, and a mixture of the two is inferior to either. Recyclers must either separate different types of plastics or process the recycled material for less specialized uses. Manufacturers label plastic containers with numbers that indicate their polymer type and make it easier to recycle these materials. Table 13-5 shows the recycling number scheme. 

The BFS technology is an advanced aseptic processing technique which allows plastic containers to be formed by means of molded extruded polymer granules, filled, and sealed in one continuous process. This differs from conventional aseptic processing where container formation, preparation, and sterilization, and container filling and closiu e are all separate processes. 

HDPE by itself is a safe plastic material on account of its chemical inertness and lack of toxicity . Film and containers made from HDPE are used on a large scale in food and drug packaging and HDPE has been used in prosthetic devices including hip and knee joint replacements. All these applications underscore polymer safety. If articles made of HDPE contain fillers, processing aids, and colorants, their toxic effects must be estimated separately. 

The selective treatments of flame-retardant plastics are fulfilled when the WEEE plastics are treated (recovered, recycled, thermally disposed) together with other wastes, as is the case with energy recovery processes that are currently practiced in Europe.78 79 In this scenario, the joint recovery of plastics containing brominated flame-retardants with other materials complies with the purpose of the WEEE Directive without the removal requirement of Annex II. Recent technical studies and legal reviews demonstrate that WEEE plastics containing brominated flame-retardants are compatible with the EU WEEE Directive without separation and removal prior to the waste treatment. This has been confirmed by the 2006 EU Member States guidance on the separation requirements of the WEEE Directive.80... 

Most of the membranes listed in Table 5.20 are formed through phase separation processes, i.e., melt extrusion or coagulation of a polymer solution by a nonsolvent. In melt extrusion, a polymer melt is extruded into a cooler atmosphere which induces phase transition. The melt extrusion of a single polymer usually gives a dense, isotropic membrane. However, the presence of a compound (latent solvent) that is miscible with the polymer at the extrusion temperature but not at the ambient temperature, may lead to a secondary phase separation upon cooling. Removal of the solvent then yields a porous isotropic membrane. Anisotropic membranes may result from melt extrusion of a dope mixture of polymers containing plasticizers. 

Municipalities and cities are beginning to collect plastic bottles, any type of rigid plastic container, and in some cases plastic films. Film is often the most predominant component of plastic on a weight basis. Further development of process and separation technologies is necessary for mixed plastics if widespread recycling of plastic bottles, containers and film is to be increased. This report discusses technologies which have been developed for the separation and processing of waste plastics. 

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