Fully Biobased Composites of an Itaconic Acid Derived Unsaturated Polyester Reinforced with Cotton Fabrics

In this study, a fully biobased composite reinforced by cotton fabrics was successfully fabricated by copolymerizing a bioderived unsaturated polyester (PEOI) with a green diluent, dimethyl itaconate (DI). The PEOI prepolymer was synthesized from itaconic acid (IA), oxalic acid (OA), and ethylene glycol (EG) via a simple polycondensation process and was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and viscosity measurements. Subsequently, the prepolymer was dissolved in DI to prepare a polymerizable unsaturated polyester resin (UPE) with low viscosity, excellent reactivity for free radical polymerization, and good compatibility with cotton fibers. After being reinforced by cotton fabrics, the resulting composites showed satisfactory material performance, including a strong tensile strength at break of approximately 34 MPa, a glass transition temperature (Tg) of approximately 108 °C, and thermal decomposition temperatures (Td5%) ranging from 224 to 276 °C. These green composites derived from renewable resources are hopeful candidates for replacing petroleum-based UPE resins, and the family of IA derivatives may play promising roles in fabricating fully biobased composites.