The Impact of Molecular Weight on the Characteristics of Injection‐Molded Partially Crystalline Thermoplastic Polyimide R‐<scp>BAPB</scp>

ABSTRACT This study investigates the correlation between the molecular weight of semicrystalline polyimide and the properties of injection moldings based on it. It was found that the degree of crystallinity can be increased by annealing of molding. The molecular weight of polyimide materials directly influences their glass transition temperature. An increase in molecular weight leads to a decrease in both the degree of crystallinity and the rate of crystallization within these materials. The mechanical properties of a polymer, such as its tensile strength, elastic modulus, and elongation at break, show a direct relationship with its molecular weight. As the molecular weight of a polymer increases, its strength, stiffness, and ability to elongate at break increase. Crystallization annealing leads to an increase in the rigidity of the material, but at the same time, there is a decrease in its plasticity, which is expressed in a decrease in elongation at break.