Role of nanoclay in determining microfibrillar morphology development in PP/PBT blend nanocomposite fibers

Abstract

The aim of this work is to study the effect of organically modified montmorillonite (Cloisite 30B) on the microfibril formation of poly (butylene terephthalate) droplets in polypropylene/poly (butylene terephthalate)/organoclay blend nanocomposites during melt spinning process. An attempt is also made to investigate the effect of compatibilizer on partitioning of organoclay in this system. The nanocomposite samples were prepared via melt compounding by using a co-rotating twin screw extruder. The melt viscoelastic results along with the SEM micrographs revealed that nanoclay can have different effects on microfibril formation depending on the nanoclay partitioning which could be strongly controlled by nanoclay concentration. In the samples with low organoclay content (1 wt%), the nanoclay platelets mostly located in the interface and had no appreciable effect on the extent of microfibril formation while at higher organoclay loadings major part of nanoclay selectively partitioned inside the PBT droplets which reduced the droplet deformability and,hence, the extent of microfibril formation. This led to fibrils with rough surface and broad diameter size distribution which could be related to non-uniform organoclay distribution inside the PBT droplets as evidenced by TEM micrographs. However, incorporation of compatilizer was found to promote the migration of nanoclay from PBT to PP matrix; the mechanism which improved the microfibrillar morphology development.