Modification of waste poly( ethylene terephthalate) (PET) by using poly(L-lactic acid) (PLA) and hydrolytic stability

The purpose of this study is the preparation of hydrolytically degradable copolymers of waste poly( ethylene terephthalate) ( PET). To achieve this, we modified PET by using biodegradable poly( lactic acid) (PLA). Modification reactions were carried out in o-nitrophenol as solvent at 140 and 170 degrees C for 8, 16, and 24 h in the presence of dibutil tin oxide (DBTO) as catalyst. The amount of the total polymers ( PLA and PET) in the reaction mixture was 30% by weight, and the weight ratios of PLA/PET were 10/90, 50/50, and 90/10. These modified products were characterized by Fourier transform infrared spectrometer ( FTIR), differential scanning calorimeter (DSC) as well as by hydrolytic degradation determinations. Hydrolytic degradations of the products were determined gravimetrically. Disc-shaped samples were placed in tubes containing phosphate buffer solution of pH 7.2 and kept in a water bath at 60 degrees C for 28 days. The weight loss of the products after hydrolytic degradation ranged from 1.25% to 48.75% after 28 days.