Analysis of Mechanical Properties of Low Density Polyethylene/Rice-Husk Composite using Micro Mathematical Model Equations.

Abstract

Low Density Polyethylene and Rice-Husk of 0.300μm particle size were melt-blended together by extrusion process and the mechanical properties of the composite were investigated using ASTM D638 test method with Instron testing machine of LK10K and model-3 type. Experimental results showed that tensile strength and percentage elongation of the composite exhibited a gradual decrease with increase in filler loading while tensile modulus and hardness showed gradual improvement with increase in filler loading. The correlative analysis of the mechanical properties of the composite was compared with the experimental results and the results from the micro mathematical model equations. The result showed that there is a distinct variation between the experiment results and results from micro mathematical model equations. The mechanical properties of the composite indicate that it may useful in some applications that require low strength, high stiffness and hardness. Key Word Composite, Filler Loading, Low Density Polyethylene, Mechanical Properties. Mathematical Model Equations, Rice-Husk, Introduction The use of natural fibers as particulate fillers are known to have different effects when combined with different thermoplastics, and in most cases, improve the impact strength, stiffness, heat distortion temperature and cost reduction [1]. In this regard, rice-husk/thermoplastics composites has been found to be of great relevance in automotive applications, building construction, control of environmental pollution and plastic composite either with or without the aid of some common compatibilizers. However, the pulverized rice-husk owes its outstanding modification effect on its dimensional stability, biodegradability, renewability, and compatibility [2]. Recent interests on the inadequate final disposal (open burning, land filling) of rice-husk, and its resistance to decomposition in the soil, difficult digestion and low nutritional value to animals has led to the development of a new product with thermoplastic and lignocellulosic material [3]. Various works on the application of natural fibers like Flax, hemp, jute, straw, wood fiber, wheat, barley, oats, cane (sugar and bamboo), grass reeds, kenaf, ramie, oil palm empty fruit bunch, sisal, coir, water hyacinth, pennywort, kapok, papermulberry, raphia, banana fiber, pineapple leaf fiber and papyrus as the reinforcing agent in plastic composites have been reported. For instances, there has been many reports on the use of wheat straw fibers for production of composites, panel boards and powdered wheat straw for anion exchangers [4]. Yang et al [5] investigated the effect of compatibilizing agents on the mechanical properties and morphology of thermoplastic polymer composites filled with rice husk flour and reported that compatibilizing agents improved the mechanical properties better. Madufor and Enyiegbulam [6] carried out a systematic study on the mechanical properties of LDPE/Cassava/Wood Four composites and pointed out that the composite is useful in furniture and allied products. Sapuan et al [7] reported the study on tensile and flexural strength of coconut spathe and sapthe fibre reinforced epoxy composite. The results showed that tensile strength of coconut sapthe-fibre is inferior to other natural fibre such as cotton, coconut coir and banana fibres, and suggest that fibre treatment may improve the interfacial bonding between fibre and matrix leading to better mechanical properties of coconut sapthe-fibre reinforced composite laminates. Sharifah, Martin, and Simon [8] studied the mechanical properties of composites manufactured from polyester resin with Kenaf fiber that blows to a height of at least 10 meter. Composites based on biologically degradable polyester amide and plant fiber (flax and cottons) with good mechanical properties, such as sufficient water resistance and biodegradability, have also been investigated by Jiang and Hinrichsen [9]. Generally, fine particles when well dispersed within the polymer resin improves the stiffness and impact behavior of the resin [1]. This work is aimed at effective utilization of rice husk wastes as particulate fillers in modification of thermoplastics to improve their impact strength, dimensional stability and moisture absorption characteristics, and provide an alternative and better way of disposing the rice husk waste IOSR Journal of Engineering Mar. 2012, Vol. 2(3) pp: 399-407 ISSN: 2250-3021 www.iosrjen.org 400 | P a g e 2.0 Experimental 2.1 Materials Materials used for the study include Low density polyethylene (with density of 0.922g/cm 3 , melt flow index (MFI) of 4.0g/10min at 190 0 C, produced by Thai Polyethylene Co Ltd, China), rice-husk wastes collected from a local farm at Atani, Ogbaru L.G.A. Anambra state, and the pulverizing machine used for break the rice-husk into particle size of 0.300μm. 2.2 Apparatus and Equipment This includes single screw extruder, universal instron testing machine, pulverizing machine, electronic weighing machine, dumb bell cutting machine, Hardness testing machine, sieve. 2.3 Composite Preparation The rice-husk was sun-dried in an open air, grounded thoroughly and sieved to obtain a fine powder of 0.300μm diameters. LDPE and varying amount (1, 3, 5, 7 wt %) respectively of the rice husk powder were weighed using electronic weighing balance. Components of each composite sample were obtained using the formulations in Table 1.0 and combinations were done in %wt. The composites were prepared using a single screw extruder fitted with a slit die at a mixing speed of 100rpm and extruding temperature of 130 0 C, and cut to a dumb bell shape. Typical dimensions of dumb bell test samples were 135mm X 14mm X 2.0mm as shown in Fig 1.0 Table 1.0: The formulation of the composite samples.