Effects of poly(lactic acid) and polybutylene succinate ratios on properties of composite foams containing activated carbons

Polymer blends of poly(lactic acid) (PLA) and polybutylene succinate (PBS) containing activated carbon (AC) were foamed through an extrusion process using azodicarbonamide (ADC) as a blowing agent. The influence of PLA:PBS ratios on the bubble formation, cellular structure and size, foam density (ρ_f), void fraction (V_f) cell density, melt flow index (MFI) and crystallinity (X_c) were investigated. PBS acted as nucleation sites for the cellular generation at low concentrations due to the incompatibility of PLA and PBS in nature. The thicker cell walls occurred with smaller cell sizes and higher cell density at high PBS contents as a result of high melt viscosity. The crystallinity (X_c) of each polymer in composite foams was lower than that of un-foamed polymers and declined with the reduction of polymer proportions.