Polymers, domestic plastic waste

There are basically five different polymers that contribute to the total amount of domestic plastic waste, namely, PE, PP, PS, PVC, and PET. The composition of this MPW can change depending on the regional habits and seasons of a year, and also on the mode of waste collection. A typical composition may be PE 39%, PVC 22%, PET 19%, PS 8%, and PP 12% (by wt). 

Details are given of a visit by RECOUP to BP Chemical s feedstock recycling demonstration unit in Sunbury. The feedstock recycling technology has been developed by a consortium of companies, and will enable polyolefin rich plastic waste from domestic and commercial sources to be vapourised and then condensed to form a hydrocarbon wax. This can then be used to feed existing petrochemical crackers to produce polymers indistinguishable from virgin material, it is claimed. 

Incineration of engineering and domestic wastes of inhibited plastics is inefficient in terms of energy production and leads to contamination of the atmosphere by harmful combustion products. In addition, incineration requires thorough sorting of waste, which is uneconomic. According to statistical information [25], incineration of a ton of polymer scrap is twice as expensive as recycling and five times expensive as burial. To obtain official permission to build an incineration plant is in fact improbable in many countries in the world today. 

Moreover, PP/LDPE blends are the products of plastic recycling. Since separation of PP and PE in sohd domestic waste (SDW) is very expensive, many recycling companies sell mixtures of reworked PE and PP ( polymer mix ) [13]. Thus, the study of the stmcture of blends of these materials will increase the field of application of recycled plastics. This is the reason for why PP-LDPE blends are the main subject considered in this chapter. 

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