Abstract
The aim of this work was to investigate the effect of lithium chloride (LiCl) on the fibre length distribution, melting temperature and the rheological characteristics of high yield pulp fibre reinforced polyamide biocomposite. The inorganic salt lithium chloride (LiCl) was used to decrease the melting and processing temperature of bio-based polyamide 11. The extrusion method and Brabender mixer approaches were used to carry out the compounding process. The densities and fibre content were found to be increased after processing using both compounding methods. The HYP fibre length distribution analysis realized using the FQA equipment showed an important fibre-length reduction after processing by both techniques. The rheological properties of HYP-reinforced net and modified bio-based polyamide 11 “PA11” (HYP/PA11) composite were investigated using a capillary rheometer. The rheological tests were performed in function of the shear rate for different temperature conditions. The low-temperature process compounding had higher shear viscosity; this was because during the process the temperature was low and the mixing and melting were induced by the high shear rate created during compounding process. Experimental test results using the extrusion process showed a steep decrease in shear viscosity with increasing shear rate, and this melt-flow characteristic corresponds to shear-thinning behavior in HYP/PA11, and this steep decrease in the melt viscosity can be associated to the hydrolyse reaction of nylon for high pulp fibre moisture content at high temperature. In addition to the low processing temperature, the melt viscosity of the biocomposite using the Brabender mixer approach increases with increasing shear rate, and this stability in the increase even at high shear rate for high pulp moisture content is associated to the presence of inorganic salt lithium chloride which creates the hydrogen bonds with pulp during the compounding process.
Highlights
Short-fibre reinforced polymer composites are extensively used in manufacturing industries due to their light weight and improved mechanical properties [1] [2]
Experimental test results using the extrusion process showed a steep decrease in shear viscosity with increasing shear rate, and this melt-flow characteristic corresponds to shear-thinning behavior in high yield pulp (HYP)/Polyamide 11 (PA11), and this steep decrease in the melt viscosity can be associated to the hydrolyse reaction of nylon for high pulp fibre moisture content at high temperature
This study demonstrates that it is possible to process HYP fibre with highthermoplastic-engineering bio-based polyamide
Summary
Short-fibre reinforced polymer composites are extensively used in manufacturing industries due to their light weight and improved mechanical properties [1] [2]. Various experimental studies have investigated the effect of flexibility on fluid viscosity They concurred that the more flexible the fibres are, the more pronounced their effect on the rheological characteristics is [7] [8] [9]. A recent study on the effect of fibre-length distribution on the rheological behavior of castor-oil composite showed that at high fibre length, the shear viscosity becomes more dependent on shear rate [10]. This behavior is due to elastic deformation of the fibres [10]
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