Muhammad M. Rahman

Enhanced tensile performance of epoxy and E-glass/epoxy composites by randomly-oriented amino-functionalized MWCNTs at low contents

Effect of amino-functionalized multi-walled carbon nanotubes (NH2-MWCNTs) on the tensile performance of epoxy and E-glass/epoxy composites was investigated. Low weight percentages (0.3 and 0.4u2009wt%) of NH2-MWCNTs were dispersed into a DGEBA epoxy resin using combination of sonication and three-roll milling methods. Composites with plain weave E-glass fabrics were fabricated by compression molding process. Tensile test results showed a significant enhancement in strength, modulus and toughness of epoxy and E-glass/epoxy composites at 0.3u2009wt% loading of NH2-MWCNTs. Micrographs of NH2-MWCNTs-incorporated epoxy and E-glass/epoxy composites revealed better dispersion of nanotubes in epoxy, better bonding between nanotubes and polymer and improved interfacial adhesion between fiber/matrix at 0.3u2009wt% loading. Micromechanical models were used to predict the tensile properties and compared with the experimental results. An improved dispersion and hence an enhanced crosslink interaction between NH2-MWCNTs and epoxy lead to the improvements in the tensile properties of the epoxy nanocomposites close to predicted values at 0.3u2009wt% loading. A similar rationale applies for the increase in properties of E-glass/epoxy nanocomposites.

Improvement in Mechanical and Thermo-Mechanical Properties of Carbon fibre/Epoxy Composites Using Carboxyl Functionalized Multi-Walled Carbon Nanotubes

Investigations were carried out to optimize mechanical and thermal performances of carbon fibre/epoxy composites modified with functionalized carbon nanotubes. For fabricating carbon fibre/epoxy nanocomposites, 0.1-0.4 wt.% carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs-COOH) were incorporated in an epoxy system. Laminates were cured at a temperature of 65.55 °C. The effects of MWCNT on flexural, interlaminar shear strength (ILSS),tensile and thermo-mechanical properties of carbon fibre/epoxy composites were studied. The results obtained from flexural, ILSS, tensile and dynamic mechanical analysis (DMA) of carbon fibre/epoxy demonstrated a linearly increasing trend in properties up to 0.3 wt.% MWCNT loading. Results obtained from the thermal mechanical analysis showed a linearly decreasing trend in coefficient of thermal expansion up to 0.3 wt.% MWCNT loading. The properties were lower at 0.4 wt.%, due to agglomeration that may have resulted in poor wetting of the carbon fibres.

Optimization of Low-Velocity Impact Properties of E-Glass/Epoxy Composites Using Plasticizing Modifiers

The prime aim of this work is to enhance the energy absorbing capabilities of e-glass/epoxy composite under low velocity impact using plasticizing modifiers. Epoxy terminated polyol at 5–15 phr loading levels as plasticizing modifier was mixed into two-phase SC-15 epoxy resin system by a high speed mechanical stirrer. Modified epoxy resin system was then used to fabricate E-glass/epoxy composites by hot press processing. Low velocity impact test at two different energy levels was carried out to investigate the effectiveness of incorporating plasticizing modifier on impact properties of these composites. In addition, three point bend test was also conducted to examine the effects on flexure properties with plasticizing modifiers. Incorporation of epoxy terminated polyol in E-glass/epoxy laminates proved efficient with a significant improvement of 23% in impact energy absorption capability over control counterpart. On the other hand, flexure strength and modulus has been decreased upon polyol loading whereas failure strain has been increased. The flexible polymer chain of polyol group inserted between epoxy molecules by chemical reaction enhances the ductility of the composites and reduces the number of cross-linking. Hence, energy absorption capability or overall toughness was found to increase with a slight reduction of peak strength and flexure strength and stiffness.Copyright