Preparation of lightweight PBS foams with high ductility and impact toughness by foam injection molding

Lightweight and highly tough polymer foams play a crucial role in resource conservation and environmental protection. One such biodegradable material that has garnered attention for its excellent processability and mechanical properties is polybutylene succinate (PBS). However, achieving PBS foams with superior mechanical properties remains a significant challenge. In this study, we prepared PBS foams with higher ductility and impact toughness using foam injection molding. The improved ductility of these foams can be attributed to the highly oriented cellular structure along the direction of the tensile load, transforming from regular circular shapes to tubular ones. This cellular structure effectively blunts crack tips, thereby enhancing impact performance. When the mold-opening distance is 0.4 mm, the fracture elongation of PBS foams is 486%, the tensile toughness is 4,586 MJ·cm−3, and the impact strength is 12.73 kJ·m−2. These values are 98%, 53%, and 29% higher than those of unfoamed PBS, respectively. As the mold-opening distance increases, the relative density of PBS foams decreases, leading to a reduction in fracture elongation, tensile toughness, and impact strength. Interestingly, the specific impact strength of PBS foams consistently surpasses that of unfoamed PBS, and increases proportionally to the mold-opening distance.