Synthesis and characterization of fully bio-based unsaturated polyester resins

The sustainable tomorrow for future generations lies with the present industrial development toward the proper utilization of various bio-based products. For a transition to a higher level of sustainability, it is necessary to form a new platform for advanced technology products. This paper reports the development of new fully bio-based unsaturated polyesters resins (UPRs). A series of prepolymers were synthesized by varying saturated diacids (oxalic, succinic and adipic acid), itaconic acid and 1,2-propandiol. Dimethyl itaconate was used as a reactive diluent (RD) in amounts of 30, 35 and 40 wt%. Rheological measurements showed that the obtained resins possessed viscosities (234–2226 mPa s) amenable to a variety of liquid molding techniques. The impact of composition variables—prepolymer structure and amount of RD—on the chemical, mechanical and thermal properties of the thermosets was examined by DMA, TA and tensile measurements and was discussed in detail. The tensile properties (37–52 MPa), glass transition temperature (60–97 °C) and coefficient of thermal expansion (71–168 10−6 °C−1) of the cured resins were in the desired range for UPRs. This investigation showed that UPRs based on itaconic acid can be tailored during synthesis of the prepolymer to meet the needs of different property profiles.