Sustainable Design of Poly(trimethylene succinate- <i>co</i> -terephthalate) Copolyesters: Melt Memory Effects, Accelerated Crystallization, and Enhanced Mechanical Properties

The depletion of fossil resources and escalating microplastic pollution necessitate sustainable polymer alternatives. This study develops biobased biodegradable polyesters using 1,3-propanediol (PDO) as an ecofriendly substitute for industrialized 1,4-butanediol (BDO)-based polyesters. A series of poly(trimethylene succinate-co-terephthalate) (PTST) copolyesters with varied succinic acid contents were synthesized to investigate their nonisothermal crystallization kinetics, self-nucleation behavior, and mechanical properties. Crystallization kinetics analyzed via the Jeziorny, Ozawa, and Mo models revealed composition-dependent crystallization rates, growth morphology, and activation energies. Differential scanning calorimetry identified a melt memory effect in PTST, with a self-nucleation temperature interval (147–158 °C) narrower than PBAT’s (141–162 °C), suggesting chain flexibility governs this phenomenon. Postprocessing within this interval enhanced recrystallization, improving mechanical properties without costly and time-consuming annealing. Rotational rheology further confirmed accelerated crystallization during melt cooling within the self-nucleation interval. This work provides a cost-effective strategy to optimize the PTST performance while advancing sustainable material design.