Vinay Kumar Singh

The objective of this investigation was to fabricate cross-linked polyvinyl alcohol (PVA) based laminate composites reinforced with biaxial cotton sheets. Cross-linking was done with sulfuric acid, to overcome the water solubility of PVA. A water uptake test was performed to evaluate the effect of cross-linking on the water absorption properties of the composites. Morphology, distribution and bonding between the matrix and reinforcement of the fabricated composites were studied using scanning electron microscopy. Mechanical properties such as the tensile strength (TS), modulus of elasticity and elongation of the fabricated composites material were evaluated. There was about a 56.25% increase in the TS of the cross-linked composite as compared to the neat PVA, and at 64 wt.% of cotton fiber, there was about a 56% increase in the TS as compared to the cross-linked PVA. The thermal degradation analysis of fabricated composites material was carried out by thermogravimetric analysis. The thermal stability increased with increase in cotton fiber wt.%. The viscoelastic properties of the fabricated composites material were determined by dynamic mechanical analysis. The effects of stress (4 MPa, 6 MPa and 8 MPa) and temperature (20°C and 40°C) on creep and recovery behavior of the laminated composites were studied.

In the present work walnut particle reinforced composite material was developed. Ten wt%, 15 wt%, 20 wt% and 25 wt% (weight percentage) of walnut particles were mixed with epoxy resin (CY-230). Scanning electron microscopy (SEM) shows that the walnut particles were well dispersed in the epoxy resin matrix. Addition of walnut particles increased the modulus of elasticity of the bio composite. Addition of walnut particles in bio composite decreased the ultimate strength both in compression and tension. However, addition of walnut particles in bio composite increased the hardness. Flexural modulus of elasticity also increased with increasing walnut particles weight percentage, whereas flexural strength and strain decreased with increased weight percentage of walnut particles.

An epoxy resin (EP) matrix has been modified with depolymerized natural rubber (DNR). The 0.5, 1.0, 1.5, 2.0, and 2.5 wt% DNR-filled epoxy were used for the present investigation. The primary aim of this development is to scrutinize the mechanical properties of such cured epoxy filled with DNR. When the rubber content was low, the mechanical strength was low and the free volume of DNR in epoxy matrix was less. With the increase in rubber content, the free volume of rubber in the composite increases and the mechanical strength increases; however, after a specific weight percentage of rubber, if we increase the amount of rubber, the mechanical strength decreases and the free volume of rubber in the composite increases quickly, but with the increase in DNR weight percentage in epoxy matrix, the hardness decreases. The scanning electron microscopy (SEM) results justified the results obtained from the mechanical tests.

Lately, materials research has shifted to composite materials from monolithic, adjusting to the global need for light weight, low cost, quality, and high performance in structural materials. Every effort aims to develop a material which can be appropriate for various industry and machinery purpose. In the present study, a modest attempt has been made to develop cast aluminum based silicon carbide (SiC) particulate metal matrix composite (MMC) and worked upon to raise the wettability factor between the matrix and dispersion phase. Magnesium (Mg) is used as wetting agent. It works by scavenging the oxygen from dispersoids surface and thinning the gas layer around dispersoids and this is done by forming MgO or MgAl ₂ O ₄ or both according to concentration of Magnesium added. Mg ₂ Si is the compound responsible for strengthening. The combination of aluminum and magnesium seems to have synergetic effect on wetting and give appropriate strength. All mechanical properties obtained are well correlated with microstructure obtained by Scanning electron micrograph. Differential thermal analysis (DTA) and thermo gravimetric analysis (TGA) also justified the results obtained in present investigations.