Polymer recycling: Thermodynamics and economics

Polymer recycling must conform to thermodynamic laws and economic restricti ons. The objective of polymer recycling is twofold: (t) the reduction of ru bbish and the burden of waste polymers on the environment, and (2) the cons ervation of resources. The environmental burden should be considered as par t of the cost for employing polymers. Polymer input to landfills can be red uced by source reduction, materials substitution, recycling, incineration, and/or degradation or reduction to low molecular weight compounds. While th e value of separated polymers is considerably greater than that of commingl ed ones, the separation is often difficult and requires an energy investmen t for "demixing". With present technology, this has not been justified for more than about 25% of the polymer waste feedstock. For the rest, energy re covery through incineration appears to be the thermodynamically and economi cally sensible route.