Water Resistance, Mechanical Properties and Water-Induced Shape Memory Properties of Poly(vinyl Alcohol) Materials Modified by Waste Polyester Depolymerization Monomer

Depolymerizing waste polyethylene terephthalate (PET) into monomers and subsequently processing and utilizing them is widely acknowledged as one of the most effective recycling methods for waste PET. The poor water stability of poly(vinyl alcohol) (PVA) necessitates modification to enhance its application scope. Thus, this study explores the use of recycled terephthalic acid (rTPA) obtained from waste PET depolymerization to modify PVA, aiming to improve its water resistance, functionalize it, and expand its potential applications. Initially, the k-rTPA modifier was synthesized by treating rTPA with a silane coupling agent (γ-aminopropyltriethoxysilane, KH550). Subsequently, the k-rTPA modifier was employed to enhance the mechanical properties and thermal stability of PVA. Specifically, the elongation at break of the PVA/k-rTPA mixture increased from 169.87 to 364.67%, representing a 114.6% improvement over pure PVA. Moreover, the water resistance was significantly enhanced, indicated by a reduction in the equilibrium swelling rate from 197.5 to 76.6%, marking a 157.8% increase, as well as an increase in the contact angle and extended water dissolution time. Furthermore, the PVA/k-rTPA material demonstrated remarkable water-induced shape memory properties. Consequently, the introduction of the k-rTPA modifier notably enhances the performance of PVA materials, suggesting significant potential applications and broadening its scope of utilization.