Development and Characterization of Epoxy Based Hybrid Composites Reinforced with Hair Fibers

Abstract

The research reported in this thesis essentially has four broad parts. One part is about exploring the possibility of composite making with human hair fiber as the reinforcing element in epoxy. The fabrication details of such a composite and its hybridization with secondary fillers have been discussed. The physical, mechanical and microstructural characteristics of these composites are presented. The following part describes the development of theoretical correlations for the prediction of effective thermal conductivity (keff) of polymer composites reinforced with short fibers and hybrid composites filled with any particulate filler along with the fiber. The third part has provided the experimental and analytical details on the dry sliding wear response of epoxy based composites reinforced with short hair fiber (SHF) and hybrid composites filled with glass microspheres in different proportions. The last part has reported on the thermal, acoustic and dielectric characteristics of the composites that includes an assessment of the effective thermal conductivities using the proposed correlations and their experimental validation. This research shows that successful fabrication of epoxy composites reinforced with short hair fiber and hybrid composites incorporated with various secondary fillers like solid glass microspheres (SGM), boron nitride (BN) and aluminum oxide (Al2O3) with solution casting technique is possible. The density and porosity of these composites are greatly influenced by the type and content of filler materials. Tensile, flexural and compressive strength of the composites can also be largely modified with the incorporation of short human hair fiber. It is further found that the wear performance of the epoxy+SHF composites can be improved significantly with the addition of solid glass microspheres and a parametric appraisal of the wear process can be made using Taguchi method. Using response surface methodology, correlations are established between the independent process parameters and output response. Further, an artificial neural networks (ANN) based model is used to predict the specific wear rates of epoxy+SHF and epoxy+SHF+SGM composites for different SHF contents and sliding velocities. It is found that reinforcement of short hair fiber improves the thermal insulation capability of the composite which can be further improved with the addition of SGM as the secondary filler. On the other hand, conductive fillers like BN and Al2O3 enhance the thermal conduction behavior of composite. An increment in the glass transition temperature (Tg) and drop in the coefficient of thermal expansion (CTE) of the composite have been observed with the reinforcement of hair fiber. Similarly, incorporation of the secondary fillers also causes enhancement in the Tg and drop in CTE of the hybrid composites. The reinforcement of hair fiber also improves the acoustic insulation ability of composite with operating frequency. It is further observed experimentally that for all such composites, hair fiber reinforcement causes a drop in dielectric constant value. Thus this work opens up a new avenue for the value added utilization of a bio waste like human hair as a reinforcing element in polymer based composites with promising application potential.