Dynamic mechanical properties of oil palm fibre (OPF)-linear low density polyethylene (LLDPE) biocomposites and study of fibre-matrix interactions

The dynamic mechanical properties of oil palm fibre (OPF) linear low density polyethylene (LLDPE) composites in terms of storage modulus (E'), loss modulus (E '') and damping parameter (tan delta) in a temperature range of 150 degrees C to 100 degrees C is presented in this paper. The effect of fibre content, fibre size and fibre surface treatment on the dynamic mechanical properties was studied. The storage modulus and damping parameters were predicted using different equations. The storage modulus and loss modulus increased with increase in fibre content and also upon alkali treatment on fibres. The glass transition temperature of pure LLDPE was -145 degrees C, which increased to -128 degrees C for composites with 40% fibre content. Fibre loading in composite and alkali treatment on fibre increased the loss modulus peak. Single tan delta peaks were observed for all the composite samples tested. The tan delta peak values decreased upon fibre addition whereas alkali treatment increased the tan delta peak at all frequencies indicating better impact properties after alkali treatment. The interfacial strength indicator values (B) decreased upon alkali treatment and higher B values were observed for composites containing fibre size range 75-177 mu followed by 425-840 mu and 177-425 mu indicating decreased order of bond strength. Activation energy was found to be high for composites with 425-840 mu size fraction (80.7 kJ mol(-1)) followed by 177-425 mu size fraction (72.6 kJ mol(-1)) and 75-177 mu size fraction (68.1 kJ mol(-1)) Storage modulus (E') and damping parameters predicted using different equations were in agreement with experimental values. (C) 2011 IAgrE. Published by Elsevier Ltd. All rights reserved.