Pultrusion of a flax/polypropylene yarn
ABSTRACT The present work reports the pultrusion of a flax reinforced polypropylene commingled yarn containing discontinuous flax and polypropylene fibers. This was the first attempt to pultrude this material. Rectangular cross-sectional profiles have been successfully produced using a self-designed pultrusion line. In a series of experiments carried out with yarns of two different flax fiber contents, the pultrusion parameters were varied. In particular, the preheating and die temperatures and also the pulling speed, which are the most relevant parameters regarding the potential future pultrusion of natural fiber composite profiles at industrial scale. A complete characterization of each profile was conducted in order to examine the influence of processing parameters on the profile quality. The mechanical properties were evaluated by performing three point bending as well as Charpy impact tests.
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ABSTRACT: Fundamental mechanisms of the pultrusion process using commingled yarns of polypropylene matrix and discontinuous flax fiber to produce thermoplastic profiles were investigated in numerical and experimental manners. Essential issue is the fact that all natural fibers are discontinuous by nature, which may negatively influence the processability. The pultrusion process will be only successful if the pulling force exerted on the solidified pultrudates can be transmitted to the regions of unmelted commingled yarns by Ã¢Â€Âœbridging overÃ¢Â€Â those melted regions within the die. This can be realized by applying a sufficient number of small yarn bundles of high compactness rather than a thicker single bundle of lower compactness as the raw material. Furthermore, the possibility of adding extra melt into the yarn bundles by side-fed extrusion has been investigated showing that the impregnation can be improved only for the outer layers of yarns, which is owed to the high viscosity of the thermoplastic melt and the limited length of the die.Research Letters in Materials Science 01/2007; DOI:10.1155/2007/37123 · 0.50 Impact Factor
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ABSTRACT: This review article describes the recent developments of natural fiber reinforced polypropylene (PP) composites. Natural fibers are low-cost, recyclable, and eco-friendly materials. Due to eco-friendly and bio-degradability characteristics of these natural fibers, they are considered as strong candidates to replace the conventional glass and carbon fibers. The chemical, mechanical, and physical properties of natural fibers have distinct properties; depending upon the cellulosic content of the fibers which varies from fiber to fiber. The mechanical properties of composites are influenced mainly by the adhesion between matrix and fibers. Chemical and physical modification methods were incorporated to improve the fiber-matrix adhesion resulting in the enhancement of mechanical properties of the composites. The most important natural fibers are jute, flax, and coir and their novel processing technics to develop natural fiber reinforced composites are also described.Journal of Reinforced Plastics and Composites 05/2009; 28(10-10):1169-1189. DOI:10.1177/0731684407087759 · 1.19 Impact Factor
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ABSTRACT: This paper deals with an experimental study on the properties of pultruded jute fiber reinforced unsaturated polyester composite (PJFRC). The ratio of fiber to matrix is approximately 70:30 by volume. Compression and flexural testing were performed in order to study the mechanical properties while TMA and DMTA were used to study the thermal properties of the composites. Morphological aspects of the composites were also evaluated using an optical and scanning electron microscope. Compression and flexural stress-strain curves showed a linear portion at initial loading phase followed by yield and plastic deformation. For the DMTA evaluation it was found that the storage modulus is strongly dependent on temperature and degrades with increasing temperature. The TMA result showed a contraction of composite upon heating instead of expansion. The acid digestion test result confirmed that the fiber content was approximately 70% by volume. (C) Koninklijke Brill NV, Leiden, 2011Advanced Composite Materials 01/2011; 20(3-3):231-244. DOI:10.1163/092430410X547047 · 0.48 Impact Factor