Recycling of plastic bottles is one of the directions of using recycled materials to renew the resource base of polymer materials. During processing, the problem of waste disposal is solved , and materials are obtained that can be sent back to production, even taking into account some restrictions (technological, hygienic, legislative, sanitary) associated with the reuse of polymers.
Due to the fact that polyethylene terephthalate (PET) has fairly stable mechanical properties, the processing of plastic bottles from it is the most developed and established way to use polymer recycled materials. There are two main types of processing - mechanical and chemical. As a rule, in most cases, the processing of PET bottles is done mechanically, since chemical requirements are high for raw materials, and the use of expensive catalysts is necessary. The mechanical method does not require plasticization of waste. PET bottles are first sorted from the remaining types of containers made of polymer (polyethylene, PVC) and foreign objects (cork, garbage). Depending on the requirements for the final product, the bottles can be sorted by color and even by type of polymer.
The initial processing of plastic bottles takes place on a knife crusher, where PET particles of 0.5-10 mm are formed as a result of technological processing. The resulting polymer chips are washed with a solution of caustic soda or water, after which it is dried according to a certain technology at a moisture content of 0.02-0.05% and a temperature of 130 º. The drying process is of great importance, failure to comply with the required moisture parameters leads to an irreversible deterioration in the quality of secondary raw materials.
After drying, the material is agglomerated, as a result of which the crumbs obtained in the previous stages of the technology are sintered into small lumps. At this stage, the processing of plastic bottles may be completed, as the agglomerate can already be used as raw material. In order to average the physical characteristics of the recyclable materials, it is granulated. As a result of it, the processed PET particles become more dense, and the resulting material is easier to use in the future and obtain the necessary materials on standard equipment.
The main directions of the use of raw materials from PET waste is the production of films, fibers and bottles. As a rule, given the mechanical and rheological (fluidity of the material) properties of recycled PET, it is used to produce containers for various chemicals. Recycled PET is not used as a container for food products. Fiber from recycled polyethylene terephthalate is most often processed into woven substrates for the manufacture of carpets and clothing or textiles. Recycled materials are also used for the manufacture of geotextiles, synthetic winterizer,
noise insulation materials, absorbent and filtering elements, electrical products, accessories (by casting), and automobile parts.