Modification of poly(ethylene terephthalate) by copolymerization of plant-derived α-truxillic acid with excellent ultraviolet shielding and mechanical properties

Ultraviolet-shielding poly(ethylene α-truxillate-co-ethylene terephthalate) (PETT) was synthesized via the addition of α-truxillic acid (TA) as a third monomer in the copolymerization modification of poly (ethylene terephthalate) (PET). The effects of TA, with its semi-flexible/semi-rigid special structure, on the chemical structure, thermal properties, crystallization behavior, ultraviolet blocking properties, and mechanical properties of PETT were then investigated. Thermal analysis revealed that a small amount of TA significantly reduced the crystallinity and melting temperature of PETT but did not affect its thermal stability. Notably, the material exhibited excellent thermal properties in processing applications. With the addition of only 10 wt%, PETT could block ~100% of the ultraviolet spectrum (<400 nm), making up for the defect that pristine PET cannot shield the UV-A spectrum (320–400 nm). The yield stress also increased significantly from 29.8 MPa for the neat PET to 40.2 MPa for PETT (10 wt% TA). In addition, the TA is plant-derived and synthesized by environmentally friendly photodimerization reaction. A small amount of TA provides PET with excellent ultraviolet shielding performance and mechanical properties, broadening its application prospects in the field of anti-ultraviolet packaging materials.