S. A. R. Hashmi

Mechanical properties of sisal fibre at elevated temperatures

Sisal fibres extracted from the leaves of Agava sisalana plants 3, 5, 7 and 9 years old were tested at different temperatures for tensile strength, elongation, toughness and modulus. The tensile strength, modulus and toughness values of sisal fibre decreased with increase in temperature. The effect of plant age on tensile strength, tensile modulus and toughness of sisal fibre became very much less at 100 °C as compared to 30 °C. Fractured fibres were observed by using a scanning electron microscope. The ends of fibres fractured at elevated temperature showed a failure similar to that of inorganic fibres. Elongation values at all temperatures increased with age. Elongated capillaries were observed in fibres fractured at 80 and 100 °C, due to the removal of moisture and volatiles originally present in the fibres. The fibrils are clearly observed in the form of hollow cylinders. Fractured surfaces are composed of brittle as well as ductile phases. The ductile portion increased with the increase of temperature.

Sliding wear of PP/UHMWPE blends: effect of blend composition

In the present investigation, a wear resistant polymer, ultra high molecular weight polyethylene (UHMWPE) was melt blended with isotactic polypropylene (PP) in different proportions. Sliding wear tests were conducted by using Cameron Plint pin-on-disc apparatus. Polymer samples in the form of the pin were tested against EN-24 steel disc at different pressures and sliding speeds. The wear volume of PP reduces significantly on the addition of UHMWPE. At 0.28 m/s sliding speed, wear rate of PP was 15×10−12 m3/m which reduces to 0.28×10−12 m3/m on addition of 15 wt.% of UHMWPE. At 1.09 m/s sliding speed, PP deforms, while 15 wt.% of UHMWPE sample does not show significant deformation. Wear loss of 15 wt.% UHMWPE filled PP blend significantly low as compared to PP. Reduction in wear loss of UHMWPE filled PP blend has been attributed to the reduction in temperature of contact surface. Worn surface of the test sample showed two distinct morphological regions.

Effect of addition of polycarbonate on sheared flow of red mud-filled isotactic polypropylene

Different volume fractions of polycarbonate (PC) were incorporated to improve thermal stability of red mud (RM) filled polypropylene (PP). Effects of PC addition in RM filled PP on shear stress, melt viscosity, and melt elasticity have been determined under different shear rates by using a capillary rheometer. With the increase in shear rate, addition of PC in RM-filled PP reduced its shear stress and melt viscosity. However, recoverable shear strain increased with PC content in the blend.

Influence of steady shear flow on dynamic viscoelastic properties of un-reinforced and Kevlar, glass fibre reinforced LLDPE

An experimental study was conducted to observe the effects of parallel-superposed flow condition on viscoelastic properties of LLDPE, Kevlar fibre reinforced LLDPE and hybrid of short glass fibre and Kevlar fibre reinforced LLDPE. Parallel-plate rheometer was employed for these tests. Rheological parameters such as loss modulus (G″) and dynamic viscosity (η′) do not vary significantly on superposing steady state shear with oscillatory shear in the studied range of experiment at 185°C in un-reinforced LLDPE. Kevlar fibre reinforced LLDPE and Kevlar/glass fibre reinforced LLDPE showed significant changes in the flow behaviour under various sets of superposed conditions. Storage modulus (G′), andG″ become highly sensitive to low oscillatory angular frequencies (ω) under superposed conditions. These curves show two different regions with increased ω value. At low ω values, parametersG′ andG″ change sharply reaching a certain value, thereafter, changes are moderate with increased ω. In case of η′ a maxima is observed, position of which, depends upon the value of steady shear rate. Maxima shifts towards higher frequencies with the increased steady shear rate.

Mechanical Properties of Sunhemp Fibre — Polystyrene Composites

Sunhemp fibre-polystyrene composites were developed by using chopped sunhemp organic fibres and polystyrene. Sunhemp fibres impregnated in polystyrene solution were used for making composites under heat and pressure. Different. compositions of sunhemp and polystyrene were used for preparing there composites. Fibre reinforcement improved the flexural and impact strengths of composite. Impact strength data showed that maximum impact strength could be achieved by reinforcing 38 weight percent of fibres. Further reinforcement sharply decreased the impact strength. In case of flexural strength behaviour of composite, flexural strength decreased from 1.75 to 1.55 N/m m2 with the increase of fibre contents from 33.5 to 36 weight percent. Deflection in three point flexural testing decreased with increase of fibre content in the composite. Fracture behaviour of composites has been explained on the basis of fibre-polymer bonding.

Effects of hybrid composition of LCP and glass fibres on abrasive wear of reinforced LLDPE

The hybrid of liquid crystalline polymer (LCP) fibres and glass fibres (GF) provide a combination of modulus and toughness to semi-crystalline linear-low-density-polyethylene (LLDPE). LCP and GF fibres reinforced composites were studied using two-body abrasion tester under different applied loads. Two sets of fibre reinforced LLDPE, 10 and 20 vol%, were investigated. The contents of LCP and glass fibres were varied as 25, 50, 75 and 100 vol% of overall volume of fibres in LLDPE. The effect of replacing glass fibre with LCP fibre on wear is reported. Wear loss increased with the applied loads and glass fibre contents in LLDPE. The replacements of glass fibres with LCP fibres improved abrasive wear resistance of composite. The composite containing 20 vol% of glass fibres in LLDPE showed the specific wear rate nearly double to that of LCP fibre reinforced LLDPE. Incorporation of LCP fibre improved wear resistance of glass fibre reinforced LLDPE. Worn surfaces were studied using SEM. Glass fibres were broken in small debris and removed easily whereas LCP fibres yielded to fibrillation during abrasive action. The overall wear rate was governed by the composition and test conditions.

Tribological Behavior of Redmud Filled Polyester Composites

Abrasive wear behaviour of different composition redmud polyester composites was studied by using SUGA abrasion tester. Wear loss was more in case of 5Phr composite as compared to 15 Phr redmud polyester composites. Effect of particle size on wear loss was also observed and explained on the basis of the microstructures of the worn surfaces.