Recycling of poly

Dissolution/reprecipitation processes were evaluated for the recycling of poly-epsilon-caprolactam (PA6) and polyhexamethyleneadipamide (PA66). The process involved solution of the polyamide in an appropriate solvent, precipitation by the addition of a non-solvent, and recovery of the polymer by washing and drying. Dimethylsulphoxide was used as the solvent for PA6, and formic acid for PA66, and methylethylketone was used as the non-solvent for both polymers. The recycled polymers were evaluated by determination of molecular weight, crystallinity and grain size. Excellent recoveries were achieved, with no deterioration in the polymer properties. 33 refs. 

Paszun, D. and Spychaj, T Chemical recycling of poly(ethylene tereph-thalate), Ind. Eng. Chem. Res., 36, 1373-1383 (1997). 

C.M. Simon and W. Kaminsky, Chemical recycling of poly(tetrafluoroethylene) by pyrolysis, Polym. Degrad. Stab., 62, 1-7 (1998). 

Japon, S., Leterrier, Y. and Manson, J.-A. E., Recycling of poly(ethylene terephdialate) into closed-cell foams, Polym. Eng. ScL, 40, 1942 (2000). Letenier, Y., Laboratoiie de Technologie des Composites et Polymeres (LTC), Ecole Polytechnique Eederale de Lausanne (EPEL), CH-1015 Lausanne, Switzerland, personal communication, 2001. 

Tsuneizumi et al. [13] studied the chemical recycling of poly(lactic acid)-based polymer blends using environmentally benign catalysts, clay catalysts, and enzymes. Poly(L-lactic acid) (PLLA)-based polymer blends (e.g., PLLA/polyethylene [PE] and PLLA/poly(butylenes succinate) [PBS]) were degraded into repolymerizable oligomer. 

Nerkar M, Bandyopadhyay S, Kamalakaran R, Gupta S, Guo H. Recycling of poly(phen-ylene ether) blends. J Appl Polym Sci 2011 120(5) 2921-7. 

Paszun D, Spychaj T. Chemical recycling of poly (ethylene terephthalate). Ind Eng Chem Res 1997 36 1373-1380. 

Evstatiev M, Fakirov S, Krasteva B, Friedrich K, Covas J A and Cunha A M (2002) Recycling of poly(ethylene terephthalate) as polymer-polymer composites, Polym Eng Sci 42 826-835. 

Recycling of poly(butylene terephthalate) (PBT) faces similar problems. PBT is preferable used for injection molding applications due to its fast crystallization and the low uptake of water. It is often blended with PET, polycarbonate (PC) or polystyrene, containing various kinds of additives as fire retardants, dyes and fillers, as well. Any kind of recycling concept has to deal with this after-use disadvantages. 

Hu, L.-C. Oku, A. Yamada, E. Tomari, K. Alkali-Decomposition of Poly(ethylene terphthalate) in Mixed Media of Nonaqueous Alcohol and Ether. Study on Recycling of Poly(ethylene terephthalate). Polym. J. 1997, 29, 708-712. 

Fig. 12 Recyclability of poly (SBF)4PMnCI for styrene oxidation with PhIO(Ae)2 as oxidant...

Paszun D and Spychaj T (1997) Chemical recycling of poly(ethylene terephthalate),... 

Soeda Y, Toshima K, Matsumura S (2004), Enzymatic synthesis and chemical recycling of poly(carbonate-urethane) , Macromol Biosci, 4, 721-728. 

M. Evstatiev, S. Fakirov, B.Krasteva,K. Friedrich, J. A. Covas M. Cunha. Recycling of Poly(ethylene terephthalate) as Polymer-Polymer Composites. Polym. Eng. Sci., 42, 826-835 (2002). 

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