The Effects of Antioxidants Content on Mechanical Properties and Water Absorption Behaviour of Biocomposites Prepared by Single Screw Extrusion Process
The performance of hybrid fillers between rice husk and sawdust filled recycled high density polyethylene (rHDPE) with the presence of antioxidants (IRGANOX 1010 and IRGAFOS 169, with the ratio of 1？:？1) was investigated. The biocomposites with 30？wt% of matrix and around 70？wt% of hybrid fillers (rice husk and sawdust) and different antioxidants’ contents (0 to 0.7？wt%) were prepared with single screw extruder. Increasing the amount of antioxidants in biocomposites reduced the modulus of elasticity and modulus of rupture on flexural testing. The addition of antioxidants increased the tensile and impact strength of biocomposites. From the study, samples with 0.5？wt% of antioxidants produce the most reasonable strength and elasticity of biocomposites. Furthermore, the effect of antioxidants content on water uptake was minimal. This might be caused by the enhanced interfacial bonding between the polymer matrix and hybrid fillers, as shown from the morphology by using scanning electron microscopy (SEM). 1. Introduction The large amount of disposable bottles presently produced makes the search for alternative procedures for recycling of these materials imperative. As chemical processing is most often costly and sometimes aggressive to the environment, a possible solution is the recycling of such material by thermomechanical techniques [1]. Great attention has been focused on the addition of natural fibres as reinforcement for plastics, replacing glass fibres and other synthetic materials. This is due to environmental concerns and also for providing a good combination of high performance, great versatility, and processing advantages at lower cost. Some drawbacks reduce the application of natural fibers as reinforcement in polymers, such as the incompatibility between fibres and polymer matrices, the tendency to form aggregates during processing, and the poor resistance to moisture. Incompatibility of components is responsible for poor thermal and mechanical properties. The stress transfer from the matrix to the fibre depends on fibre-fibre and fibre-matrix interactions [2]. To overcome this problem, it is necessary to promote polymer modification with polar groups (such as maleic anhydride or glycidyl methacrylate stearic acid) to enhance the adhesion between the composite components. The coupling agent more often used for this application is a polyethylene graft maleic anhydride (MAPE). Interactions between the anhydride groups of maleated coupling agents and the hydroxyl groups of natural fibres can overcome the incompatibility and increase tensile and
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