Development of biobased unsaturated polyester resin containing highly functionalized castor oil

A highly functionalized castor oil product mainly composed of castor oil pentaerythritol glyceride maleates (COPERMA) was employed to fabricate a partial biobased unsaturated polyester resin (UPR) through blending it with petroleum-based UPR. The COPERMA product synthesized was characterized by FT-IR, 1 H NMR, and ESI-MS to determine its possible structure and its functionality. The 1 H NMR results showed that the maleate C C functionality of the COPERMA product was high (2.62). This highly functionalized product was then mixed with 35   wt% styrene before blending this mix with petroleum-derived UPR to prepare a new partial biobased UPR. Physical, thermal, and mechanical properties of the UPR/COPERMA resins were carefully studied. Physical properties data indicate that the resultant biobased resins are suitable for liquid molding process and had a less shrinkage than the neat UPR. Compared to the neat UPR, the cured UPR/COPERMA resins demonstrated comparable or even better thermal and mechanical properties when the content of COPERMA resin was up to 10   wt%. When the content of COPERMA resin increased to 20   wt%, the tensile strength and storage modulus at 35   °C decreased gradually, but not as much as reported in other oil/UPR systems, while other properties, such as crosslink density, glass transition temperature, tensile and flexural moduli, and impact strength, were still improved.