i Asari, Ashraf Rohaniza
(2013)
Preparation, Properties And Durability Studies Of Hdpe – Kenaf Core Filler Composites.
Masters thesis, Universiti Sains Malaysia.
Abstract
Wood plastic composites (WPCs) were prepared using high density polyethylene (HDPE) as a matrix, maleic anhydride grafted polyethylene (MAPE) was used as coupling agent and two types of natural fillers were used which are kenaf core filler (KCF) and wood flour (WF). Parameters studied for the first stage are effect of incorporation MAPE, effect of different fillers loading and effect of different types of fillers on mechanical, thermal and water absorption properties of WPCs. Filler was compounded with HDPE by using internal mixer, filler weight fraction were 0, 20, 40 and 60%. WPCs incorporated with MAPE increased the stabilized torque, density, tensile strength, tensile modulus and strain while melt flow index (MFI) and degree of crystallinity (Xc) reduced. Percentage of water uptake reduced by 29% for KCF filled HDPE while 33% for WF filled HDPE composite if compared to uncoupled system. Density, tensile modulus, flexural strength, flexural modulus and percentage of water uptake also increased while Xc, MFI, strain and impact strength reduced for WF filled composite. KCF filled composite increase stabilized torque, Xc, tensile strength, tensile modulus, flexural strength, flexural modulus and percentage of water uptake if compared to WF filled composite. MFI, density, thermal stability, strain and impact strength are lower than WF filled HDPE composite. Second stage is effect of accelerated weathering on WPCs. HDPE and WPCs samples were weathered in xenon- arc weathering chamber for 500, 1000, 1500, 2000, 2500, and 3000 hours. Two weathering cycles were
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employed which are exposure to xenon light with water spray and exposure to xenon light only. Exposed to UV light with water spray gave crucial effect on mechanical properties of WPCs and HDPE since water accelerate degradation process. Color change, flexural properties, carbonyl index, vinyl index, Xc and surface morphology are measure after weathering For HDPE, flexural strength reduces but flexural modulus increased while flexural strength and modulus of WPCs reduce after 3000 hours when exposed to UV light with water spray. Xc of WPCs were increased at initial stages but prolong exposure time reduced Xc of WPCs. Changes in lightness increased for WPCs when exposed to UV light with water spray or to UV light alone. Carbonyl index of WPCs were higher than HDPE in any conditions but vinyl index of HDPE was the highest in both conditions. Carbonyl index and vinyl index of samples usually higher in exposure of UV light and water spray if compared to UV light alone.
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