Unidirectional Pre-stretching and Isothermal Annealing Reinforced Poly(butylene carbonate) Sheets at Room Temperature

Semicrystalline polymers usually undergo multilevel microstructural evolutions with annealing and stretching processes, which is essential to tailor the physical properties of the polymer. Here, poly(butylene carbonate) (PBC) sheets were prepared via isothermal annealing and unidirectional pre-stretching processes, then the changes of PBC in crystallinity, mechanical properties, thermal properties and microscopic changes before and after annealing and stretching were measured, as well as the relationship between microstructure and macroscopic properties before and after stretching. The strengthening mechanism of PBC was also described. It was demonstrated that shish-kabab structure emerged under the pre-stretching process. With the increase of the tensile ratio, the crystallinity, structure and mechanical properties are increased differently. Among them, the crystallinity and tensile strength after annealing-stretching treatment increased to 24.45% and 104.5 MPa, respectively, which were about 1.55 times and 3.4 times of those without any treatment.