Investigation on thermoplastic co‐poly(ether‐ester) elastomer toughened poly(methylmethacrylate) blends

Blends of poly(methyl methacrylate) (PMMA) and copoly(ether‐ester) (COPE) elastomer have been prepared in different compositions namely, 95/5, 90/10, 85/15, and 80/20 wt % (PMMA/COPE), by melt mixing technique using twin screw extruder. The influence of COPE content on the mechanical properties especially impact strength, thermal behavior, and chemical resistance of PMMA have been investigated. The impact strength of the PMMA/COPE blends for all the compositions were found to be improved remarkably as compared to the virgin PMMA without affecting the other mechanical properties significantly. Various composite models, such as series model, parallel model, Halpin‐Tsai equation, and Kerner's model have been used to fit the experimental mechanical properties. The effect of chemical and thermal ageing on the performance of the PMMA/COPE blends was also studied. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Investigations on the influence of graphite filler on dry sliding wear and abrasive wear behaviour of carbon fabric reinforced epoxy composites

In this experimental study, the dry sliding wear and two-body abrasive wear behaviour of graphite filled carbon fabric reinforced epoxy composites were investigated. Carbon fabric reinforced epoxy composite was used as a reference material. Sliding wear experiments were conducted using a pin-on-disc wear tester under dry contact condition. Mass loss was determined as a function of sliding velocity for loads of 25, 50, 75, and 100 N at a constant sliding distance of 6000 m. Two-body abrasive wear experiments were performed under multi-pass condition using silicon carbide (SiC) of 150 and 320 grit abrasive papers. The effects of abrading distance and different loads have been studied. Abrasive wear volume and specific wear rate as a function of applied normal load and abrading distance were also determined.The results show that in dry sliding wear situations, for increased load and sliding velocity, higher wear loss was recorded. The excellent wear characteristics were obtained with carbon-epoxy containing graphite as filler. Especially, 10 wt.% of graphite in carbon-epoxy gave a low wear rate. A graphite surface film formed on the counterface was confirmed to be effective in improving the wear characteristics of graphite filled carbon-epoxy composites. In case of two-body abrasive wear, the wear volume increases with increasing load/abrading distance. Experimental results showed the type of counterface (hardened steel disc and SiC paper) material greatly influences the wear behaviour of the composites. Wear mechanisms of the composites were investigated using scanning electron microscopy. Wear of carbon-epoxy composite was found to be mainly due to a microcracking and fiber fracture mechanisms. It was found that the microcracking mechanism had been caused by progressive surface damage. Further, it was also noticed that carbon-epoxy composite wear is reduced to a greater extent by addition of the graphite filler, in which wear was dominated by microplowing/microcutting mechanisms instead of microcracking.     

Blends of styrene butadiene styrene TRI block copolymer/polyaniline-Characterization by WAXS

Electrically conductive blends based on polyaniline-dodecylbenzene sulphonic acid (Pani.DBSA)/styrene-butadiene-styrene (SBS) block copolymer have been prepared by two methods namely melt mixing and polymerization of aniline in the presence of SBS using in situ polymerization method. The influence of composition and synthetic methods on the performance of SBS/Pani blends was established. The obtained SBS/Pani blends have been characterized by mechanical, morphological and electrical properties. A great reduction in volume resistivity values with increase in Pani content was noticed for in situ polymerization method compared to melt mixing method. The microstructural parameters were also computed using Wide Angle X-ray Scattering (WAXS). The results are compared with mechanical and electrical properties.     

Three‐body abrasive wear behavior of E‐glass fabric reinforced/graphite‐filled epoxy composites

The present article summarizes an experimental study on three‐body abrasive wear behavior of glass fabric reinforced/graphite particulate‐filled epoxy composites. The wear behavior was assessed by rubber wheel abrasion tests (RWAT). The angular silica sand particle sizes in the range 200–250 μm were used as dry and loose abrasives. The tests were carried out for 270, 540, 810, and 1,080 m abrading distances at 22 and 32 N loads. The worn surfaces were examined using scanning electron microscopy (SEM). The results showed varied responses under different abrading distance due to the addition of glass fabric/graphite filler into neat epoxy. It was observed that the glass fabric reinforcement to epoxy matrix (G‐E) is not beneficial to abrasive wear resistance. Further, inclusion of graphite filler to glass fabric reinforced epoxy composite performed poorly resulting in significant deterioration in wear performance while the neat epoxy showed better wear performance. Selected mechanical properties such as hardness, ultimate tensile strength, and elongation at fracture were analyzed for investigating wear property correlations. The worn surface features were studied using SEM to give insight into the wear mechanisms. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers