Synthesis of hyperbranched poly(ethyleneimine) based macromolecular antioxidants and investigation of their efficiency in stabilization of polyolefins

Macromolecular antioxidants with highly suppressed leaching to the environment, based on hyperbranched poly(ethyleneimine) carrier with bonded sterically hindered phenol and alkyl compatibilizing groups with various chain length were synthesized and tested for their efficiency in stabilization of polyolefins. The synthesis of the macromolecular antioxidants was carried out by amidation of the amine groups present in poly(ethyleneimine) with various carboxylic acids containing sterically hindered phenol and compatibilizing groups, such as n-butyryl, lauryl or stearyl. The structure of the resulting polymers was analyzed by H-1 NMR and by GPC. The antioxidant content of the samples was determined by UV-Vis spectroscopy. The efficiency of the synthesized antioxidants in thermooxidative stabilization of polypropylene was determined by chemiluminescence. The efficiency in photostabilization of polypropylene and polyethylene was investigated by using FT IR and UV-Vis spectroscopies. It was found that the macromolecular antioxidant which did not contain any compatibilizing groups shows the best stabilizing efficiency in both thermooxidative and photooxidation tests. The extent of extraction of the synthesized macromolecular antioxidants from polypropylene films was investigated as well. Low extent of extraction of the macromolecular antioxidants from the polypropylene films was observed in contrast to the high level of leaching of commercially used low molecular weight phenolic antioxidant. These results indicate the environmental advantage of the investigated poly(ethyleneimine) based macromolecular antioxidants over the widely applied low molecular weight compounds. (C) 2015 Elsevier Ltd. All rights reserved.