The impact of a designed lactic acid-based crosslinker in the thermochemical properties of unsaturated polyester resins/nanoprecipitated calcium carbonate composites

Unsaturated polyester composites (UPCs) were prepared from biobased unsaturated polyester resins (UPRs) and nanoprecipitated calcium carbonate (NPCC). The UPRs were obtained from the crosslinking reaction of an unsaturated polyester (UP) made from renewable monomers and styrene (St) or a mixture of St with a designed lactic acid-based crosslinker (BPPC). The UPCs were obtained by adding the NPCC to the formulations. Aspects of the composition of the UPs and of the BPPC were confirmed by FTIR and H-1 NMR spectroscopies. Different UPCs were prepared and the influences of the addition of NPCC and of the amount of BPPC on their thermomechanical properties were evaluated. The BPPC has a major influence on the properties of the UPCs, namely a significant improvement of mechanical properties and of the thermal stability of UPCs. Both results suggest that the BPPC may be acting as a compatibilizer between the polymer matrix and the filler.