engleski

Products of Chemically Recycled PET Evaluated by FTIR Spectroscopy

Poly(ethylene-terephtalate), PET is a versatile polymer used in the manufacture of various kinds of packaging ; especially for soft drink bottles, fibres and films. The use of huge volumes of PET is attributed to its excellent thermal and mechanical properties, crystal clear transparency and non-toxic nature. However, PET does not create a direct hazard to the environment and its recycling is of great importance due to obtained high quality material and products. Several methods have been proposed for recycling waste PET and the most attractive method is chemical glycolysis into the corresponding monomers or raw chemicals that could be reused. In the present study, the glycolysis reaction was carried out at various temperatures with a weight ratio PET/EG=1:18 and time of 1-6 h in the presence of zinc acetate as a transesterification catalyst. The glycolysed products were separated and the yield of obtained bis(2-hydroxyethylterephtalate), BHET monomer and the content of oligomers were calculated. Further on, monomer and oligomers were identified by FTIR, TGA and DSC techniques. The FTIR spectrometer was used to identify the chemical structure of the glycolysis products along with neat PET, monomer BHET and various oligomers by monitoring changes in absorbance of the characteristic groups of each product. The main changes of absorbance are the appearance of (-OH) stretching at 3430 cm-1 indicating alcohol and acid hydroxyl end groups, absorbance of (-C=O) stretching at 1720 cm-1 due to acid groups and ester (-C-O) bands at 1245cm-1. Glycolysis of waste PET lead to the production of monomer BHET and various types of oligomers that could be used in the synthesis of a number of polymeric materials like unsaturated polyester resins and PET to novel biocompatible systems. Results show that the products of PET chemical recycling are mainly low molecular oligomers and monomers.

poly(ethylene-terephtalate); recycling; FTIR

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