Polymerizable UV absorbers for the UV stabilization of polyesters. II. Photodegradation study of UV-stabilized PET copolymers

Polymerizable UV absorbing monomers (UVAMs) were copolymerized with bis(hydroxyethyl) terephthalate to yield copolymers of poly(ethylene terephthalate) (PET). PET copolymer films containing 3-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-3-hydroxyphenoxy]-1,2-propanediol (UVAM 12) and 6,6'-(6-phenyl-1,3,5-triazine-2,4diyl)bis(3-(2-hydroxyethoxy)phenol) (UVAM 24) were exposed to UV radiation for 1082 hrs. in a QUV-A accelerated weathering instrument and analyzed periodically using FT-IR spectroscopy and GPC. It was found that PET films containing copolymerized UVAMs outperformed films containing admixed Tinuvin 1577 stabilizer, thereby offering even greater protection to polymer films against UV-induced crosslinking and chain scission.