Nirmal Saha

Tensile behaviour of unidirectional polyethylene-glass fibres/PMMA hybrid composite laminates

Abstract Unidirectional hybrid composite laminates based on high-performance polyethylene fibres and glass fibres were prepared with partially polymerized methyl methacrylate at room temperature, followed by heating at 55°C (well below the softening point of polyethylene fibres) for a stipulated time. It was observed that the tensile strength, modulus of elasticity and hybrid effect of the laminates depend on the relative proportion of both the fibres.

Stress relaxation behaviour of unidirectional polyethylene-glass fibres PMMA composite laminates

Abstract Unidirectional composite laminates based on glass fibres (GF) and high performance polyethylene fibres (PEF) and their hybrids were prepared with partially polymerized methyl methacrylate at room temperature, followed by heating at 55°C (well below the softening point of PEF) for 2 h. The stress relaxation behaviour of the composites were determined and analysed. It was found that at all strain levels, the rate of stress relaxation decreased by incorporation of GF in GF-reinforced composite laminates (GFRC) but the reversed behaviour was found in the case of PEF-reinforced composite laminate (PEFRC). An interesting observation of the study was that the rate of stress relaxation decreased linearly in two steps in the case of PEFRC, whereas in the case of GFRC, it decreased in one step. The rate of stress relaxation was increased with the increase of relative proportion of PEF in the hybrid composites and at a higher proportion of PEF, it decreased in two steps like PEFRC.

Stress-relaxation behavior of Unidirectional polyethylene-carbon fibers : PMMA hybrid composite laminates

Unidirectional composite laminates based on carbon fibers (CF) and high-performance polyethylene fibers (PEF) and their hybrids were prepared with partially polymerized methyl methacrylate (MMA) at room temperature, followed by heating at 55°C (well below the softening point of PEF, 147°C) for 2 h. The stress-relaxation behavior of the composites were determined and analyzed. It was found that at all strain levels the rate of stress relaxation decreased by the loading of CF in CF-reinforced composite laminates (CFRC); however, the reverse behavior was found in the case of PEF-reinforced composite laminate (PEFRC). An interesting observation of the study was that the rate of stress relaxation decreased linearly in two steps in the case of PEFRC, whereas in the case of CFRC, it decreased in a single step. In the case of hybrid composites, the stress relaxation decreases in two steps as in PEFRC.

Impact behavior of unidirectional polyethylene–glass fibers: PMMA hybrid composite laminates

Unidirectional (UD) hybrid laminates based on glass fibers (GF) and high performance polyethylene fibers (PEF) were prepared with partially polymerized methyl methacrylate (MMA) at room temperature followed by heating at 55°C (well below the softening point of PEF) for 2 h. Izod impact strength of the composites was then measured. An interesting observation of the study was the change in impact strength that was largely dependent on the position of GF and PEF ply/plies present within the hybrid laminates. When the ply/plies of PEF were at the impacted surface, the impact strength showed a higher value than that of the case when GF ply/plies were at the impacted surface of the hybrid laminates.

Heat-distortion temperature of unidirectional polyethylene–glass fiber–PMMA hybrid composite laminates

Unidirectional (UD) composite laminates based on high-performance polyethylene fibers (PEF) and glass fibers (GF) and their hybrids were prepared with partially polymerized methyl methacrylate (MMA) at room temperature, followed by heating at 55°C (well below the softening point of PEF, 147°C) for 2 h. The heat distortion temperatures (HDT) of the composites were measured and analyzed. The dependency of the HDT correlated with the wettability of the fibers, measured from the contact angle. The HDT of the composites increased with increasing GF content but decreased when PEF was used. An optimum combination of different properties was obtained by using PEF/GF/PMMA hybrid composites, with GF ply/plies on the lower tension side of the UD laminates.

Tensile behavior of unidirectional polyethylene fibers PMMA and glass fibers—PMMA composite laminates

Unidirectional (UD) composite laminates based on glass fibers (GF) and high-performance polythylene fibers (PEF) were prepared with partially polymerized methyl methacrylate (MMA) at room temperature, followed by heating at 55°C (well below the softening point of PEF) for 2 h. The tensile strength, modulus of elasticity, fiber efficiency and strength efficiency of both the composite laminates, loaded parallel to the fibers, at the same volume fraction range, were investigated. All the properties were compared between the two composite laminates. It was observed that the measured tensile strength and modulus of elasticity deviated from the values calculated from the Rule of Mixture (ROM). The deviation was minimal at the lower volume fraction of fibers, and increased with the fiber volume. An interesting feature that was observed was that the efficiencies of PEF-reinforced composite was higher than that of the GF-reinforced composite at the same volume fraction of the fibers.