Microcellular foaming behaviors of chain extended poly (butylene succinate)/polyhedral oligomeric silsesquioxane composite induced by isothermal crystallization

Currently, the fabrication of microcellular semi-crystalline polymer foams using supercritical CO2 as a blowing agent had attracted worldwide interest. In this paper, a novel and facile isothermal crystallization induction method was proposed to prepare biodegradable microcellular semi-crystalline poly (butylene succinate) (PBS) foams by supercritical CO2. In order to improve melt viscoelasticity and increase cell nucleation number, chain extender (CE) and polyhedral oligomeric silsesquioxane (POSS) were introduced into PBS through melt blending method. Differential scanning calorimetry results showed that with the addition of CE and POSS, the crystallization temperature of various PBS samples increased and their crystallinity kept unchanged almost. Compared with those of pure PBS, the complex viscosity and storage modulus of chain extended PBS (CPBS), PBS/POSS and CPBS/POSS increased. The effect of chain extension, POSS addition and induction time on the foaming performance of various PBS samples was studied systematically. Microcellular CPBS/POSS foam was successfully fabricated at the induction time of 18 min and foaming temperature of 90 °C, in which the cell size and volume expansion ratio could reach 6.80 ± 1.21 μm and 7.48 ± 0.03 times, respectively. Finally, the formation mechanism of various PBS foams by isothermal crystallization induction method was presented and the thermal conductivity of various PBS foams was investigated.