engleski

FTIR Study of Poly(ethylene-terephthalate) During Mechanical Recycling Process

The practice of polymer recycling is continuously growing in order to minimize polymer waste and ensure environmental protection. However, the mechanical properties, durability and aesthetics of recycled material must not be lost in order to be acceptable for further use. Poly(ethylene-terephthalate), PET, is polymer material which is intensively used in many applications, mainly for production of bottles for storing soft drinks and mineral water. In recent years use of PET bottles is enormously growing as well as quantity of collected waste PET. For this reason procedures for PET recycling are constantly developing1. In the present work the mechanical recycling of PET was studied. It was carried out through the preparation of poly(ethylene-terephthalate)/high density polyethylene (PET/HDPE) polymer blends with low content of HDPE (3 to 15 mas %). Furthermore, modified PET/HDPE polymer blends were also prepared by addition of two types of modifiers: a) EPDM90/HDPE10 (polymer blend EPDM/HDPE 90:10) b) PET10/HDPE90 (polymer blend PET/HDPE 10:90) Changes in PET/HDPE polymer blends during recycling process were determined by FTIR spectroscopy. Samples were also characterized by titration of carboxyl groups and scanning electron microscopy. From the obtained results it can be seen that PET depolymerization occurs during the mechanical recycling process due to exposure of polymer to high temperatures. FTIR spectroscopy reveals characteristic changes in PET spectra due to depolymerization process when increased formation of carboxyl end groups is observed. Their content was also determined by titration. It can be also concluded that the use of modifiers prevents PET depolymerization. Modifier acts as polymer chain extender during mechanical recycling process and causes recovery of depolymerized PET. It can be concluded that the use of modifier enables preparation of PET/HDPE polymer blends with improved miscibility and properties.

poly(ethylene-terephthalate); recycling; FTIR spectroscopy

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