Effect of nanoclay and nano-calcium carbonate content on the properties of polybutylene succinate/nanoparticle composites

Abstract

How nanoparticle type and content affect polybutylene succinate (PBS) properties were investigated by varying nanoclay and calcium carbonate nanoparticles (nanoCaCO₃) from 0 to 15 wt%. PBS/nanoparticle composites were prepared by compounding with a co-rotating twin-screw extruder and forming them with a compression molding machine. Their mechanical properties, filler dispersion, crystallinity, and permeability were evaluated using tensile testing, energy dispersive X-ray analysis, transmission electron microscopy, differential scanning calorimetry, X-ray diffraction, and water vapor and gas permeability measurements. The results showed that adding nanoclay and nanoCaCO₃ enhanced the PBS stiffness. In comparison to neat PBS, the highest tensile moduli were 46% higher at 15 wt% nanoclay and 30% higher at 15 wt% nanoCaCO₃. The ultimate tensile strength (UTS) for the PBS/nanoclay composites tended to decrease as the nanoclay content increased. Nanoclay dispersion was poor in composites containing more than 5 wt% nanoclay. Surface treating the nanoCaCO₃ particles with a fatty acid resulted in similar UTS values and reduced the elongation at break to 15% from 225% for the neat PBS. The decrease in ductility resulted from PBS chain scission. The nanoclay and nanoCaCO₃ at low content enhanced the PBS crystallization. The nanoplatelet-shaped nanoclay led to greater agglomeration than the cubic-shaped nanoCaCO₃, but the nanoclay was more effective than the nanoCaCO₃. The water vapor barrier properties improved with the added nanoclay, with about a 52% reduction in water vapor permeability as compared to neat PBS. The water vapor and oxygen barrier properties of nanoclay were more effective than the nanoCaCO₃.