Structure and Properties of Polypropylene-Layered Silicate Nanocomposite Fibers and Nonwovens

Layered silicate (nanoclay) based additives have shown great potential in polymer and plastic applications because they overcome many limitations of traditional microcomposites. But there were only few studies on nanoclay-modified fiber systems. As fiber based systems are known to provide many beneficial characteristics because of their high surface area, a combination of nanocomposite technology and fiber formation is highly sought after. The main focus on this study is to analyze the structure-property relation of nanoclay-polymer composites in fiber and nonwoven formation process.;Polypropylene is selected as a host polymer matrix for this research and nanocomposite fibers of polypropylene and precompounded material of nanoclay based on organically modified montmorillonite is produced by melt spinning process. Addition of nanoclay might result in alteration of polymer melt rheology and crystallization kinetics, which are the key factors affecting microstructure formation during the fiber melt spinning. As polypropylene is semicrystalline in nature, changes in fiber fine structure will greatly affects its mechanical properties. Therefore changes in fiber fine structure parameters such as crystallinity, crystal size, crystal orientation, rate of crystallization and molecular orientation were studied using differential scanning calorimetry, wide angle X-ray diffraction, interference microscopy. Mechanical properties of nanoclay-PP composite fibers were studied and related to the changes in the microstructure caused by the addition of nanoclay.;Nanoclay types have significant effect on the polypropylene/nanoclay interaction and fiber properties. A comparison between different clay types Nanomax and Cloisite samples were carried out on nature of polymer/nanoclay dispersion, fiber fine structure and fiber properties. In order to analyze the effect of surfactant concentration, two different Cloisite samples with different surfactant concentration was chosen. Presence of compatibilizer plays a significant role in improving the compatibility between nanoclay and polypropylene. Polypropylene grafted maleic anhydride (PP-g-MA) with two different MFI values was chosen as the compatibilizer. They were mixed with PP/Cloisite type nanoclay samples in such a way that nanoclay to compatibilizer ratio is 1:2. Based on the polypropylene/nanoclay interaction, fiber fine structure changes and fiber properties, type of compatibilizer and nanoclay to compatibilizer ratio were fixed for spunbond process.;Spunbond thermal bonded fabrics were produced with different nanoclay additives at different concentration. Spunbond fabrics of polypropylene/compatibilizer samples were also produced and used as control. Changes in mechanical property and thermal behavior after nanoclay addition were analyzed and related to the structural changes caused by the presence of nanoclay particles. In order to analyze the effect of distribution of nanoclay on mechanical properties, bicomponent spunbond fibers were produced with nanoclay located either in core or sheath and compared for their mechanical properties.;Influence of nanoclay on thermal properties of PP fibers was studied using Thermo gravimetric analyzer. Using nonisothermal degradation, activation energy required for degradation in presence of nanoclay was studied. Effect of distribution on nanoclay on thermal degradation was also studied. The mechanism by which how the presence of nanoclay affects the thermal stability of PP fibers was established.