Synthesis of 2-Methyl-1,3-Propanediol Modified Azelaic Acid-Octanediol Copolyester Plasticizers and Their Plasticizing Effect on Polyvinyl Chloride

Currently, mainstream phthalate plasticizers pose serious threats to the environment and human health. As an eco-friendly and harmless alternative, polyester plasticizers have garnered widespread attention. However, their complex preparation process and low plasticizing efficiency have limited their practical application. In this study, a series of copolyester plasticizers (POMAZ), synthesized from azelaic acid, octanediol, and various contents of 2-methyl-1,3-propanediol (MPO), were prepared via direct esterification. The preparation process is controllable, and the number-average molecular weight of POMAZ ranges from 1000 to 4000, with a thermal degradation temperature above 270°C, demonstrating excellent thermal stability. PVC samples plasticized with POMAZ showed a decrease in glass transition temperature to −30°C and increased hydrophilicity with higher MPO content. Measurements of the tensile elongation at break of plasticized PVC verified the outstanding plasticizing performance of the POMAZ series. Specifically, POMAZ-45/PVC exhibited an elongation at break of up to 975.3%, with a plasticizing efficiency reaching 273.2%.