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  • Author: N. Narasimha Murthy x
  • Materials Sciences x
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Abstract

Polyphenylene ether (PPE) is a polymer with very high glass transition temperature, superior thermal stability but poor melt processability. Mainly to improve its processability and chemical resistance, it is blended with Polystyrene (PS) and Nylon-6, respectively. In this research, ternary blends of PPE/PS/Nylon-6 were prepared using co-rotating twin screw extrusion and test specimens were injection molded. The influence of Maleic anhydride and screw speed on the mechanical and thermal properties of the ternary blends was investigated. The 40/40/20 blends, without Maleic anhydride, processed at screw speed of 600 min–1 showed highest tensile, flexural and impact strengths of 65.74 MPa, 82.22 MPa and 8.88 kJ/m2, respectively. Complete miscibility of the three polymers in the ternary blend was evidenced by scanning electron micrographs. Glass transition temperature of the ternary blend was 127 °C. High thermal and dimensional stability of the blend was evidenced by lowest volatile mass and highest residual mass at 800 °C along with decomposition temperature of 458.6 °C. Maleic anhydride was not effective as compatibilizer in improving the mechanical properties of the ternary blend.

Abstract

This paper focuses on investigating the influence of laser power, pulse frequency and scanning speed on material removal rate and surface roughness during CO2 laser surface treatment of alumina ceramics. Pulse frequency and laser power were the significant factors influencing the material removal rate and surface roughness, respectively. Adequate response surface models were established to correlate the laser parameters and the measured responses. Grey relational analysis predicted the optimal responses at 90 W laser power, 5 kHz pulse frequency and 400 mm/s scanning speed. Desirability function based Multi objective optimization results indicated that minimum material removal rate (0.5117 mm3/s) and surface roughness (0.5968 µm) are achieved at 90 W laser power, 5 kHz pulse frequency and 337.37 mm/s scanning speed which were in close agreement with Grey Relational results. Increase in homogeneity and smoothness of the laser treated alumina surface along with formation of micro recast particles away from the laser traverse path were evidenced by the SEM micrographs.