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.