Ultrastrong, High-Barrier, and Transparent Poly(butylene adipate-<i>co</i>-terephthalate) Achieved via Ligament Relaxation-Inspired Calendaring in the Cold Solid-State

The emergence of problematic materials and energy consumption is now challenging society. While numerous efforts have been made to tackle the issue of material generation, these advancements often come at the cost of significant energy consumption. In this work, we present a novel self-enhancement method inspired by ligament training, which can effectively regulate cohesive structures and fabricate ultrastrong, high-barrier, and transparent poly(butylene adipate-co-terephthalate) (PBAT) under cold solid-state conditions. This is due to relaxation training being able to inject more energy into the polymer chains, thereby reducing the relaxation of the molecular chains. Furthermore, the crystallization behavior during the relaxation training process was investigated. We demonstrated that the well-crystallized α-crystals produced in the relaxation training process serve as precursors to β-crystals. The PBAT with relaxation training (RT-PBAT) exhibited higher tensile strength of 101 MPa in the strengthening direction and storage modulus of 2030 MPa in −30 °C, representing increases of 159% and 980%, respectively, compared to pristine PBAT (39 MPa, 188 MPa). The oxygen barrier improvement factor (BIF) of 2.55 also contributed to enhanced fruit preservation capabilities. This work will open up a new path for the low-energy manufacturing of high-performance polymers.