Polycarbonates recycling

Dow ABS Nylon 6/6 Polycarbonate Polyethylene, HDPE, LDPE, LLDPE, ULDPE Polypropylene HPPP, CPPP Polystyrene HIPS, GPPS, Recycled, Advanced Styrenic Resin SAN Polyurethane Elastomers Polyolefin Plastomer PC/ABS Crystalline Polymer ABS/TPU... 

Recovery and reuse of synthetic polymers is by far the most acceptable way of dealing with the problem of waste. Items can rarely be reused as such but instead the polymers from which they are fabricated can be recycled. In principle, polymers can be recycled without any significant loss of their properties. For example, polycarbonate bottles can be recycled into automobile bumpers and then into articles for high performance housing. 

A method of converting polycarbonate (PC) to bishydroxyethyl ether of bisphenol A (BHE-BPA) was studied, with a view to recycling PC plastic wastes. Treating PC in ethylene glycol with a catalytic amount of sodium hydroxide produced the monohydroxyethyl ether of bisphenol A (MHE-BPA, 42%), BHE-BPA (11%) and BPA (42%). BHE-BPA was produced quantitatively when 1.6 mol. equiv. ethylene carbonate was added to this reaction system. The reaction of BPA with EC produced both BHE-BPA and MHE-BPA, indicating that ethylene carbonate was formed as an intermediate in the base catalysed reaction of PC with ethylene glycol. A large proportion of this ethylene carbonate formed from PC was, however, lost by decarboxylation so additional ethylene carbonate must be provided for the quantitative preparation of BHE-BPA. 12 refs. 

Economic and ecological aspects of chemical recycling are examined, and the application of such processes to the recovery of monomers and intermediates from PETP, polyamides, polyurethanes, polycarbonates, unsaturated polyesters, polyacetals, PMMA and PS is discussed. 17 refs. SNIA... 

Polyester-6/oe/ -polycarbonate, 7 646 Polyester bottles, recycling, 20 54-56 Polyester can coatings, 13 39 Polyester carbonates, 19 822 Polyester-carboxyl powder coatings 1998 production, 7 49 Polyester composites, cross-linked, 20 114 Polyester composition, determining, 20 21 Polyester diols, 25 476... 

Polyester manufacture, organic titanium compounds in, 25 123 Polyester materials, recycling, 20 22 Polyester/polyether/polycarbonate,... 

R. Balart, L. Sanchez, J. L6pez, and A. Jimenez, Kinetic analysis of thermal degradation of recycled polycarbonate/acrylonitrile-butadi-ene-styrene mixtures from waste electric and electronic equipment,... 

Research on the pyrolysis of thermoset plastics is less common than thermoplastic pyrolysis research. Thermosets are most often used in composite materials which contain many different components, mainly fibre reinforcement, fillers and the thermoset or polymer, which is the matrix or continuous phase. There has been interest in the application of the technology of pyrolysis to recycle composite plastics [25, 26]. Product yields of gas, oil/wax and char are complicated and misleading because of the wide variety of formulations used in the production of the composite. For example, a high amount of filler and fibre reinforcement results in a high solid residue and inevitably a reduced gas and oiFwax yield. Similarly, in many cases, the polymeric resin is a mixture of different thermosets and thermoplastics and for real-world samples, the formulation is proprietary information. Table 11.4 shows the product yield for the pyrolysis of polyurethane, polyester, polyamide and polycarbonate in a fluidized-bed pyrolysis reactor [9]. 

Electrical and electronic devices are made utilizing several various types of plastic materials, thus when discarded their waste is difficult to recycle. The plastics employed in housing and other appliances are more or less homogeneous materials (among others PP, PVC, PS, HIPS, ABS, SAN, Nylon 6,6, the pyrolysis liquids of which have been discussed above). However, metals are embedded in printed circuit boards, switches, junctions and insulated wires, moreover these parts contain fire retardants in addition to support and filler materials. Pyrolysis is a suitable way to remove plastics smoothly from embedded metals in electrical and electronic waste (EEW), in addition the thermal decomposition products of the plastics may serve as feedstock or fuel. PVC, PBT, Nylon 6,6, polycarbonate (PC), polyphenylene ether (PPO), epoxy and phenolic resins occur in these metal-containing parts of EEW. 

Phosgene is an important intermediate in the manufacture of polycarbonate and polyurethane. U.S. 6,500,984 (to General Electric) describes a process for phosgene using carbon and silicon carbide catalysts. U.S. 6,054,104 (to DuPont) describes a process using a silicon carbide catalyst. U.S. 4,231,959 (to Stauffer Chemical) describes a process with recycle of unconverted CO. Estimate the cost of production for a world-scale plant. Which catalyst or combination of catalysts would you recommend ... 

NEC has a target to phase out the use of all halogenated flame retardants by 2011. In 1999 the company launched a polycarbonate containing a silicone flame retardant that it claims to be far superior to conventional flame retardants and is neither phosphorus nor halogen based and can be recycled up to five times for the same purpose. 

Acetone and phenol can be recovered after the neutralization of the acidic mixture from the cleavage reactor with sodium hydroxide or phenolate solution. The neutralized mixture is then subjected to a series of distillations. Acetone is first distilled, then cumene is recovered, together with a-methylstyrene, which is either purified and marketed or hydrogenated back to cumene and recycled to the oxidation. Phenol is finally distilled with a purity up to 99.99%, suitable for the production of polycarbonate grade bisphenol A and other chemicals and polymers. 

Use 10-60 times, then remake into a different object with a long life (polycarbonate milk bottle recycled into a part for an automobile). 

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