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4 results on '"Jasbir Singh Kunnan Singh"'

1. Effects of PTFE Micro-Particles on the Fiber-Matrix Interface of Polyoxymethylene/Glass Fiber/Polytetrafluoroethylene Composites

Author

Jasbir Singh Kunnan Singh, Yern Chee Ching, De Shin Liu, Kuan Yong Ching, Shaifulazuar Razali, and Seng Neon Gan

Subjects
coefficient of friction, wear, surface etch, PTFE, POM, interface, Technology, Electrical engineering. Electronics. Nuclear engineering, TK1-9971, Engineering (General). Civil engineering (General), TA1-2040, Microscopy, QH201-278.5, Descriptive and experimental mechanics, QC120-168.85
Abstract

Reinforcing polyoxymethylene (POM) with glass fibers (GF) enhances its mechanical properties, but at the expense of tribological performance. Formation of a transfer film to facilitate tribo-contact is compromised due to the abrasiveness of GF. As a solid lubricant, for example, polytetrafluoroethylene (PTFE) significantly improves friction and wear resistance. The effects of chemically etched PTFE micro-particles on the fiber-matrix interface of POM/GF/PTFE composites have not been systematically characterized. The aim of this study is to investigate their tribological performance as a function of micro-PTFE blended by weight percentage. Samples were prepared by different compositions of PTFE (0, 1.7, 4.0, 9.5, 15.0 and 17.3 wt.%). The surface energy of PTFE micro-particles was increased by etching for 10 min using sodium naphthalene salt in tetrahydrofuran. Tribological performance was characterized through simultaneous acquisition of the coefficient of friction and wear loss on a reciprocating test rig in accordance to Procedure A of ASTM G133-95. Friction and wear resistance improved as the micro-PTFE weight ratio was increased. Morphology analysis of worn surfaces showed transfer film formation, encapsulating the abrasive GF. Energy dispersive X-ray spectroscopy (EDS) revealed increasing PTFE concentration from the GF surface interface region (0.5, 1.0, 1.5, 2.0, 2.5 µm).

Published
2018
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2. Optimization of Mechanical Properties for Polyoxymethylene/Glass Fiber/Polytetrafluoroethylene Composites Using Response Surface Methodology

Author

Jasbir Singh Kunnan Singh, Yern Chee Ching, Luqman Chuah Abdullah, Kuan Yong Ching, Shaifulazuar Razali, and Seng Neon Gan

Subjects
polyoxymethylene, polytetrafluoroethylene, surface etch, RSM, optimization, Organic chemistry, QD241-441
Abstract

This paper investigated the effects of polytetrafluoroethylene (PTFE) micro-particles on mechanical properties of polyoxymethylene (POM) composites. Since PTFE is immiscible with most polymers, the surface was etched using sodium naphthalene salt in tetrahydrofuran to increase its surface energy. The effects of two variables, namely PTFE content and PTFE etch time, on the mechanical properties of the composite were studied. Experiments were designed in accordance to response surface methodology (RSM) using central composite design (CCD). Samples were prepared with different compositions of PTFE (1.7, 4.0, 9.5, 15.0, or 17.3 wt %) at different PTFE etch times (2.9, 5.0, 10.0, 15.0, or 17.1 min). Four mechanical properties of the POM/GF/PTFE composites, that is, strength, stiffness, toughness, and hardness, were characterized as a function of two studied variables. The dependency of these mechanical properties on the PTFE etch conditions was analyzed using analysis of variance (ANOVA). Overall desirability, D global index, was computed based on the combination of these mechanical properties for POM/GF/PTFE composites. The D global index was found to be 87.5%, when PTFE content and PTFE etch time were 6.5% and 10 min, respectively. Good correlation between experimental and RSM models was obtained using normal probability plots.

Published
2018
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3. Discrete element method study of shear-driven granular segregation in a slowly rotating horizontal drum

Author

Ram Chand, Jasbir Singh Kunnan Singh, Chiow San Wong, and Sithi V. Muniandy

Subjects
Materials science, General Chemical Engineering, Mixing (process engineering), Drum, Mechanics, Granular material, 01 natural sciences, Discrete element method, 010305 fluids & plasmas, Condensed Matter::Soft Condensed Matter, Physics::Fluid Dynamics, Shear rate, Shear (sheet metal), Core (optical fiber), Classical mechanics, 0103 physical sciences, Rotating drum, General Materials Science, 010306 general physics
Abstract

Segregation and mixing of granular materials are complex processes and are not fully understood. Motivated by industrial need, we performed a simulation using the discrete element method to study size segregation of a binary mixture of granular particles in a horizontal rotating drum. Particles of two different sizes were poured into the drum until it was 50% full. Shear-driven segregation was induced by rotating the side-plates of the drum in the opposite direction to that of the cylindrical wall. We found that radial segregation diminished in these systems but did not completely vanish. In an ordinary rotating drum, a radial core of smaller particles is formed in the center of the drum, surrounded by larger revolving particles. In our system, however, the smaller particles were found to migrate toward the side-plates. The shear from anti-spinning side-plates reduces the voidage and increases the bulk density. As such, smaller particles in the mixer tend to move to denser regions. We varied the shear by changing the coefficient of friction on the side-plates to study the influence of shear rate on this migration. We also compared the extent of radial segregation with stationary side-plates and with side-plates moving in different angular directions.

Published
2017

4. Optimization of mechanical properties for polyoxymethylene/glass fiber/polytetrafluoroethylene composites using response surface methodology

Author

Luqman Chuah Abdullah, Jasbir Singh Kunnan Singh, Kuan Yong Ching, Seng Neon Gan, Yern Chee Ching, and Shaifulazuar Razali

Subjects
Toughness, Materials science, Polymers and Plastics, Central composite design, Glass fiber, Composite number, 02 engineering and technology, Article, lcsh:QD241-441, chemistry.chemical_compound, lcsh:Organic chemistry, 0203 mechanical engineering, polyoxymethylene, Response surface methodology, Composite material, polytetrafluoroethylene, Polytetrafluoroethylene, Polyoxymethylene, RSM, surface etch, optimization, General Chemistry, 021001 nanoscience & nanotechnology, Surface energy, 020303 mechanical engineering & transports, chemistry, 0210 nano-technology
Abstract

This paper investigated the effects of polytetrafluoroethylene (PTFE) micro-particles on mechanical properties of polyoxymethylene (POM) composites. Since PTFE is immiscible with most polymers, the surface was etched using sodium naphthalene salt in tetrahydrofuran to increase its surface energy. The effects of two variables, namely PTFE content and PTFE etch time, on the mechanical properties of the composite were studied. Experiments were designed in accordance to response surface methodology (RSM) using central composite design (CCD). Samples were prepared with different compositions of PTFE (1.7, 4.0, 9.5, 15.0, or 17.3 wt %) at different PTFE etch times (2.9, 5.0, 10.0, 15.0, or 17.1 min). Four mechanical properties of the POM/GF/PTFE composites, that is, strength, stiffness, toughness, and hardness, were characterized as a function of two studied variables. The dependency of these mechanical properties on the PTFE etch conditions was analyzed using analysis of variance (ANOVA). Overall desirability, D global index, was computed based on the combination of these mechanical properties for POM/GF/PTFE composites. The D global index was found to be 87.5%, when PTFE content and PTFE etch time were 6.5% and 10 min, respectively. Good correlation between experimental and RSM models was obtained using normal probability plots.

Published
2018

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