In the study, the effect of process steps, melt viscosity and fiber type on the fiber length of biocomposites from triethyl citrate plasticized starch acetate and natural fibers was investigated. Composites were prepared by melt processing (compounding and injection molding). The lengths of fully processed fibers were determined by dissolving the starch acetate matrix and measuring the length of the remaining fibers by optical microscopy and image analysis. A clear reductive effect of the pelletising and melt processing on the fiber length was noticed. Also a reduction of fiber length along the increasing fiber content and the decreasing plasticizer content was detected. This reduction was originated from the increasing shear forces during compounding, which again depended on the increased viscosity of the material. When comparing the fully processed hemp and flax fibers, hemp fibers remained longer and fibrillated more than flax fibers, leading to higher aspect ratio. Thus, the reinforcement efficiency of hemp fibers by the processing was improved, on the contrary to the reduced reinforcement efficiency of flax fibers. In addition, the analysis of fiber dispersion and orientation showed a good dispersion of fibers in the matrix, and a predominant orientation of the fibers in the melt flow direction.
|Number of pages
|Journal of Materials Science and Engineering A
|Published - 2011
|MoE publication type
|A1 Journal article-refereed