SynopsisThe kinetics of polyesterification of the glycolyzed PET waste with adipic acid is reported. Glycolysis of PET waste was carried out with ethylene glycol at three different ratios of PET waste to glycol. The glycolyzed products could be readily polyesterified by reacting with adipic acid, to give polyester polyols with low acid number. Kinetics of polyesterification of the glycolyzed product made from 62.5% ethylene glycol (EG) and 37.5% waste were investigated further at different hydroxyl to carboxyl ratios. Reaction conditions were nonisothermal, comparable to the industrial process scheme consisting of two isothermal regions at 170" and 200°C. The kinetic results of the polyesterification of glycolyzed PET waste are compared to the polyesterification of pure diols, namely ethylene glycol and bis(hydroxyethy1) terephthalate (BHET) with adipic acid. The reactions follow second-order kinetics at 170°C and the rate of polyesterification of the mixed diol system from PET waste lies intermediate between those of the pure diols, namely, EG and BHET. Ethylene glycol exhibited the highest reactivity. At 200°C the kinetic plots of the mixed diols from PET waste were nonlinear, and thus the reaction may not follow second-order kinetics. The nonlinearity is explained in terms of the different reactivities of the different diol species in the reaction mixture. The polyester polyols, when cured with polymeric 4,4' diphenyl methane diisocyanates, gave polyurethane rigid foams and elastomers.
Arne-411 008, IndicrSyIlopSis PET waste was glycolyzed by propylene glycol at different weight ratios. The glycolyzed pmducta were analyzed for hydmxyl value, number average molecular weight., and the mount of frea glycol. The.glycolyzed products were reacted with d e i c anhydride at a hydmxyl to carboxyl ratio of 1 . 1 . The control resin wan a geaeral purpoee unsaturated polyester prepared by reacting phthalic anhydride, makic anhydride, and propylene glycoL The heating schedule of the polyeeteri6catiou was comparable to that normally employed in the indprocess, with two i e o t h d plateau of 3-4 h at 180 and 200'C. The rate of reactions and rate constants were datermined separately at 180 and 200°C. The kinetica of the PET-based unsaturated polyesters waa compared with that of the general purpaea re&. It was found that the PET waste could be depolymerized by propyleae glycol to a molecular weight range of 2'76-480. The polyeatdcation d o n a fdoweci a third-order kinetia The rates of p o l y d c a t i o n of PET based systems were higher than that of the general p w p w A. PET-baaed systems took about 10 h to reach an acid value of 32 mg KOH/g whereas the general purpoee resin took about 25 h to reach the anme add value.
SYNOPSISCorn starch was blended with styrene maleic anhydride copolymer (SMA) , ethylene-propylene-g-maleic anhydride copolymer (EPMA ) , and corresponding nonfunctional polystyrene and ethylene propylene copolymers. The concentration of starch in the blend was varied between 50 and 80% by weight. The torque generated during blending is reported as a function of starch content, mixer speed, and mixing time. Torque increased with increasing starch content for starch/SMA blends; the reverse was true for starch/EPMA blends. The torque was higher for the blends of the anhydride functional polymers compared to the blends of corresponding nonfunctional polymers. Water absorption of the blends increased with an increase in the starch content. StarchlSMA blends made at higher mixer speed or time were more water sensitive. Blends containing EPMA absorbed less water than SMA blends containing the same weight fraction of starch. Tensile strengths of blends containing functional groups were superior compared to the blends made from nonfunctional polymers. When the starch contents increased from 60 to 70%, the tensile strength remained unchanged for SMA blend but increased for EPMA blend. All samples supported the growth of microorganisms, which increased with increasing starch content. 0 1994
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