Recycling polyurethane wastes

Progress in Rubber and Plastics Technology 16, No.l, March 2000, p.61-8 CHEMICAL RECYCLING OF WASTE SATURATED POLYESTERS AND URETHANE POLYMERS TO YIELD RAW MATERIALS FOR THE PRODUCTION OF POLYURETHANES Kacperski M Spychaj T Szczecin,Polytechnic... 

CHEMICAL RECYCLING OE WASTE SATURATED POLYESTERS AND URETHANE POLYMERS TO YIELD RAW MATERIALS FOR THE PRODUCTION OF POLYURETHANES... 

Techniques for chemical recycling of waste saturated polyesters, mainly poly(ethylene terephthalate) and of waste polyurethanes to produce polyurethanes are reviewed. 29 refs. Articles from this journal can be... 

The recycling of contaminated polyurethane waste is described with reference to a glycolysis process developed by Bayer and Daimler-Benz in which the wastes from three-layer composite instrument panels are treated. The reuse of contaminated PU is achieved by dispersely integrating the impurities in the secondary polyol during the glycolytic dissociation. The impurities are modified in such a way that they act as a filler in the secondary polyol. 3 refs. 

Chicago, 11., 26th-29th Sept. 1995, p.270-4. 43C6 TERTIARY RECYCLING OF WASTE POLYURETHANE CAR SEAT FOAM Tatsumoto K Elam C C Looker M J Evans R J US,National Renewable Energy Laboratory (SPl,Polyurethane Div.)... 

J. Braslaw and J.L. Gerlock, Polyurethane Waste Recycling. Polyol Recovery and Purification, Ind. Eng. Chem. Process. Des. Dev. 23, 552 (1984). (series of articles). 

Recycling within the section on Environmental Protection the report describes BASF s approach to recycling, and the example given is of selling solvent stripped from a waste stream. Elsewhere articles feature recycling polyurethane foams and hydrogen chloride. 

Today, several industrial plants based on glycolytic treatment are in operation for the chemical recycling of polyurethane wastes, mainly those generated from the insulation and automotive sectors.2... 

FIGURE 6.6 Recycling of polyurethane waste via partial decomposition in kneader. (After Muller, P. and Reiss, R., Die Makromol. Chem., Macromol. Symp., 57, 175, 1992. With permission.)... 

The world consumption of polyurethanes (PUs) is about 7 million tons per year (2004). The furniture industry, automotive manufacture, building industry, and technical insulation are the major consumers of PUs. It has been established that approximately 10% of PUs convert into wastes during their processing. Therefore, the development of concept for the chemical recycling of PUs is of great importance. Recycling polymer waste materials and used polymers is one way to conserve natural resources and reduce environmental stress. 

Selected chemolysis processes for PET are illustrated in Figure 9.8 and tabulated in Table 9.6. These reactions yield either the original monomers or products that can be converted to other monomers. Hydrolysis can be effectively used with PET and polyurethane waste plastics in feedstock recovery (Zia et al., 2007). Reaction conditions employed are varied and these selected references do not cover them exhaustively. Aromatic polyesters, PET and poly(butylene terephthalate), have been studied intensively for feedstock recovery. PET is extensively used in soda bottles and less than 30% of the product is mechanically recycled. 

Kacperski M and Spychaj T (1999) Chemical recycling of waste ester and urethane polymers as a source of raw materials for production of polyurethane, Polimery (Warsaw) 44 1-5 (in Polish). 

Simioni F, Modesti M and Rienzi S A (1991) Recycling of polyurethane waste, Cellular Polymer P Int Conf, London. 

Polyurethane materials are extremely versatile in that it is possible to produce a large variety of structures which range in properties from linear and flexible to crosslinked and rigid. The crosslinked PURs are thermosets, which are insoluble and infusible and therefore cannot be reprocessed by extrusion without suffering extensive thermal degradation. At present, the main sources of recyclable waste are flexible PUR foams and automobile waste. Waste and scraps of these materials may consist of 15-25% by weight of total PUR foam production. 

ICI Polyurethanes and du Vergier are evaluating a PU recycling method. The three-year project aims to use a pilot plant to demonstrate the practicality of the split-phase glycolysis process that ICI has developed. Work will initially focus on flexible foams based on MDI and specially made at Id s Rozenberg plant. In the second phase, the unit will use post-industrial waste. Assuming the trials are successful, a full-scale unit to handle at least 5000 t/y of scrap foam will be built. 

Polyurethane is a very common crosslinked polymer and many materials produced from it end up as waste. Given the quantity of material, recycling is a major problem. Cryogenic pulverization systems have been developed which can process PU foam to particles smaller than 1 mm (preferably <100 pm)/ " These particles are homogenized with polyol and then reacted with isocyanates to produce foam. This foam with 5% pulverized PU foam has a density equivalent to a similar foam produced without the recycled material. A further increase in filler content causes a density increase. Pulverized PU foam particles were also tried as a filler in natural rubber vulcanizates with good results. Figure 12.10 shows the effect of PU... 

This section describes the chemical recycling, via chemolysis, of certain condensation polymers which, although being produced in significantly lower amounts than polyesters and polyurethanes, are used in important applications, and so also contribute to the plastic waste stream. 

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