Mixing of hindered amine-grafted polyolefin elastomers with LDPE to enhance its long-term weathering and photo-stability

Polyolefins are a commodity plastic family known as low cost and recyclable material, that has displayed high potencies for wide variety of applications, resulting from their desired chemical, mechanical, and physical properties. However, further modifications are needed to improve their properties to extend their service lifetime, weathering resistance, and photostability for use in outdoor applications, which are due to their low thermal and photo-stabilities. In this research, hindered amine light stabilizers were used to enhance the photo-stability of low-density polyethylene (LDPE). For this purpose, unsaturated 4-amino-2,2,6,6-tetramethylpiperidine (UATMPP) was prepared by amidation reaction of amine groups in amino-2,2,6,6-tetramethylpiperidine with acryloylol chloride of 10-undecenoyl chloride in presence of triethylamine and 4-dimethylaminopyridine. Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) exhibited successful preparation of UATMPP. UATMPP was grafted on polyolefin elastomer (POE) through melt free radical grafting method. FTIR and NMR confirmed the successful preparation of UATMPP-grafted POE. Finally, UATMPP-containing POE was mixed by LDPE through melt compounding. The results from the calculation of carbonyl index from FTIR and tensile testing after UV irradiation exhibited desired antiaging and UV-resistant properties of LDPE/POE blends, which were influenced by grafting degree of UATMPP as well as POE content (wt%).