Characterization And Size Effect Of Strain Rate Sensitivity Of Fiber Materials

Based on extensive review of literature on characterization and size effect of strain rate sensitivity of fiber materials and nano-scale inter-phase, this study is carried out for inter-phase modification using plasma treated nano SiO2 coating on carbon fibers and ultrahigh molecular weight polyethylene (HMWPE) fibers. Similarly, plasma treatments are also applied to montmorillonite (MMT), carbon nanotube (CNT), TiO2 nano particles filled polylactic acid (PLA)/polypropylene (PP) nano-composite fiber. It is found that the plasma can etch, clean and deposit on nano-particle surface resulting on an improved inter-phase. From the results of Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR), it is observed that the uniform dispersion of the plasma treated SiO2 nano particle coating on the filaments not only filled in the micro-flaws, but also introduced the activated functional groups on the particle surfaces. The results of carbon fibers, UHMWPE fibers, aramid fibers coated with silica showed the same trend. The tensile test results show the activation volumes of filaments untreated and treated with plasma ranging at nano scale are important descriptors for the properties of the nano-structural interphase between fiber surface and nano-coating, in addition to the enhanced ductility of the filaments after SiO2 nano-particle sol-gel coating.The difference in molecular structure and crystal structure between PLA and PP causes poor compatibility when they are blended. However, the compatibility and filament elongation improved when plasma treated nano-powder are added into the polymer alloy by melt compounding PP/PLA in a twin-screw extruder. The properties of the nano-composite filament depend on the morphology of the polymer fibrils and their thermal stability. It is revealed that this subsequent mechanical processing stretches the polymer chains and creates fibrils of high aspect ratios, thus resulting in superior mechanical performance of the composites compared to the raw material. The strain dependence of damping increased and the viscosity, swelling ratio decreased with the increase of the ratio of nano-particles in a certain range.In this study nano-particles such as TiO2, SiO2, ZnO2, MMT and CNT treated by the atmospheric pressure plasma employed in a blend PP/PLA composite filament, in which unique interface structure for the nano-particles is obtained while maintaining or improving mechanical performance of the composite. It is found that using dynamic mechanical test can characterize the effect of the nano-particles on the composite fibers; the activation volume may also reveal the properties of the fiber related to nano-scale structures.