Preparation And Properties Of Low Density Polyethylene (Ldpe)/ Thermoplastic Sago Starch (TPSS)/Kenaf Composites

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Date
2010
Authors
Abdul Majid, Rohani
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Publisher
Universiti Sains Malaysia
Abstract
In this research, thermoplastic sago starch (TPSS) was incorporated in low density polyethylene (LDPE). TPSS loadings were varied from 10 to 50 wt. % to study the effect of adding TPSS on tensile properties, morphology, water absorption, natural weathering and soil burial properties of LDPE/TPSS blends. Polyethylene grafted maleic anhydride (PE-g-MA) was added into the second series of blends to study the effect of the addition of compatibilizer to the properties of the blends. For the third series, kenaf fiber was incorporated in the blends to study the effect of the addition of natural fiber. Kenaf fiber loading was varied from 5 to 40 wt. % to determine the optimum kenaf fiber loading in the LDPE/TPSS/Kenaf composites. The matrix loading have been fixed with the ratio of 80 wt. % of LDPE and 20 wt. % of TPSS. Same testing has been conducted to the LDPE/TPSS/Kenaf composites with and without the additional of compatibilizer. Preparation of the blends and composites has been conducted in Haake Polydrive with the temperature of 150ºC using rotor speed of 50 rpm. The blends and composites were then compressed into 1 mm thick film using compression molding. Dumbbell shape samples were cut and used throughout the whole research. Tensile properties show that with the addition of TPSS, the tensile strength, Young’s modulus and elongation at break of LDPE/TPSS blends decreased. These results are due to the incompatibility of both materials. SEM micrograph shows that agglomeration of TPSS is higher with the increase in TPSS loading. The degradation properties of the blends also increased with the increase in TPSS loading as well as the degradation time. Tensile properties increased with the addition of PE-g-MA into the blends. This result is due to better interaction and interfacial adhesion between LDPE and TPSS. FTIR analysis also indicated an ester linkage for the compatibilized blends that prove the interaction between the two components. For the LDPE/TPSS/Kenaf composites without the addition of compatibilizer, tensile properties are better compared to the blends but agglomeration still occurred. Better tensile properties were obtained with the addition of compatibilizer as compared to the uncompatibilized composites. However, the degradation rate increased with the incorporation of PE-g-MA. This result might due to the unreactive PE-g-MA that interact with water during natural weathering and soil burial test that can increase the number of carboxylic group in the samples.
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Keywords
Preparation and properties of low density Polyethylene , thermoplastic sago starch Kenaf composites
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