No abstract

The role of feeding method, as an important parameter in competition with thermodynamic parameters, on determining the nanoclay partitioning and its impact on microfibril formation in PP/PBT blend nanocomposite fibers were investigated. In the direct feeding method in which all components were fed into the extruder simultaneously, the major part of nanoclay with almost unchanged interlayer d-spacing was located in the PP matrix and the rest of the nanoclay partitioned into the PBT dispersed phase. However in the PBT based masterbatch method nanoclay, due to much greater melt intercalation occurred, remained in PBT droplets in the form of tactoids and/or platelets. In the masterbatch feeding method, incorporation of compatibilizer assisted more fraction tactiods and/or platelets to be transferred from PBT to the PP matrix while in the direct method it enhanced the extent of melt intercalation in the PP matrix. It was demonstrated that the nanoclay concentration in PBT droplets plays an important role in the extent of the microfibril formation during the melt spinning process. While at low organoclay loading (1 wt%) fine microfibrils could be formed in the fibers prepared by both methods of feeding, at higher organoclay loading (3,5 wt%) uniform microfibrils could hardly be developed in the fibers ,particularly, in the masterbatch feeding method due to high melt elasticity of the PBT droplets and uneven distribution of platelets and/or tactoids in the droplets.

The aim of the present work was to study the effect of microstructure and microfibril formation on dyeability of polypropylene/poly(butylene terephthalate)/organoclay blend nanocomposite fibres. The blend nanocomposite samples with the same blend ratio but varying in organoclay content were prepared via melt compounding by using a co‐rotating twin screw extruder. The microfibrillar morphology and nanoclay partitioning were studied using scanning electron microscopy and transmission electron microscopy together with rheological results. The presence of nanoclay in the form of tactoids in the polypropylene matrix accelerated the dye sorption but much greater ultimate dye uptake could be achieved for the sample in which the major part of the platelets were preferentially located inside the poly(butylene terephthalate) fibrils. Although increasing the organoclay concentration increased the ultimate dye uptake, it limited the fibril formation at higher organoclay concentration. The utilisation of a compatibiliser was found to have an enhancing effect on ultimate dye uptake. This could be explained in terms of the interfacial role of the compatibiliser in improving microfibril formation as well as partitioning a fraction of nanoclay platelets inside the polypropylene matrix.