Analysis of the Film-stacking Processing Parameters for PLLA/Flax Fiber Biocomposites (original) (raw)
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Fibers, 2016
A new type of reinforcement for unidirectional natural fiber composites has been developed, where a paper layer is assembled with a layer of unidirectional flax yarns. The paper layer chemically and mechanically bonds to the loose yarns to maintain their alignment and enables better manipulability of the reinforcement during stacking in the mold. Unfortunately, the paper layer adversely affects the permeability of the whole reinforcement to liquid resin and thus limits the impregnation quality of the final part. In this paper, a technique is adopted to increase the impregnation performance by modifying the architecture of the fibrous network in the paper layer. In particular, a method has been developed to replace a proportion of the Kraft fibers by short flax fibers in the paper layer, in an attempt to open the structure and increase the paper permeability. Permeability measurements show a major improvement in global reinforcement permeability. Basic mechanical properties of resulting composites were also analysed. Results show a slight decrease in modulus and strength when the paper layer is present. This is compensated by an important reduction in variability. Furthermore, increasing the flax proportion in the paper layer limits the loss of mechanical properties, while reducing variability even further.
The Effects of Chemical Treatments of Flax Fiber on Some Engineering Properties of Biocomposite
2006 CSBE/SCGAB, Edmonton, AB Canada, July 16-19, 2006, 2006
Flax fiber, produced through a conventional scotching mill, was washed using a commercial detergent and then it was chemically treated using silane, benzoyle and peroxide. The chemically treated fibers were dried by an air-cabinet drier at 70 °C. The dried fiber were ground and truly mixed with HDPE at a ratio of 10% flax fiber and 90% HDPE. After extruding and pelleting, the mixture was fed through a rotational molding machine and composite plates were produced. The resulting composites were tested for their various mechanical properties using standard ASTM procedures. The test results indicated that the mechanical strength of the composites was higher than the plates made from HDPE, however there was no significant difference between the mechanical strength of composites produced from various chemical treatments. The optical properties of the composites were investigated using NIR spectroscopy. The % of reflectance of the NIR at a wide range of wavelength indicated that HDPE plates were easily distinguishable, however the chemically treated composites and untreated composites were not distinguishable from each other using this technique. Papers presented before CSBE/SCGAB meetings are considered the property of the Society. In general, the Society reserves the right of first publication of such papers, in complete form; however, CSBE/SCGAB has no objections to publication, in condensed form, with credit to the Society and the author, in other publications prior to use in Society publications. Permission to publish a paper in full may be requested from the CSBE/SCGAB Secretary,
Composites Part C: Open Access
The use of biomass in injection moulded or extruded thermoplastic composites is an important issue, especially when trying to add value to low-cost co-products. The objective of this work was to conduct a complete study on the morphological characterisation and carbohydrate analysis of a range of co-products obtained during the processing of flax straw. Thus, the morphology of (i) cut flax fibres, (ii) fragmented shives, and (iii) scutching and carding dusts is characterised using a dynamic image analyser with a sieving approach. These different fractions are then used to produce injection moulded composite materials. Their mechanical performances are discussed in relation to the morphology of the reinforcements, as well as their carbohydrate compositions and fine particle contents. Co-products, based on their reinforcement properties, can be classified into three categories. In all cases, a reinforcing effect is demonstrated for the tensile Young's modulus with an increase from + 24 to + 137% depending of the material. A linear relationship was observed between the cellulose content of reinforcing material and the tensile strength at break of the injection moulded composites. The results are promising for adding value to all flax co-products in plastics processing, targeting industrial applications in line with their intrinsic performances.
Pre-treatment of Flax Fibers for use in Rotationally Molded Biocomposites
Journal of Reinforced Plastics and Composites, 2007
In presenting this thesis in partial fulfilment of the requirements for a Postgraduate degree from the University of Saskatchewan, I agree that the Libraries of this University may make it freely available for inspection. I further agree that permission for copying of this thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head of the Department or the Dean of the College in which my thesis work was done. It is understood that any copying or publication or use of this thesis or parts thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made of any material in my thesis.
A Study on Flax Fiber-Reinforced Polyethylene Biocomposites
Applied Engineering in Agriculture, 2009
Flax straw and flax fibers are renewable resource and have potential for use in the manufacturing industry. In this study, flax fiber (including 58% flax shives by weight) was studied as a material to be added into polyethylene (high density polyethylene and linear low density polyethylene) in 10% by mass and processed through extrusion and injection molding to biocomposites. Five surface modification methods on flax fibers were carried out and scanning electronic micrographs were taken to analyze the surface characteristic. The biocomposite tensile strength increased and moisture absorption decreased to varying degrees after fiber surface modifications. Among those surface modification techniques, acrylic acid treatment showed a relatively good result in reducing moisture absorption and enhancing tensile properties of biocomposites. It was also found that with increased fiber content (from 10% to 30%), the tensile strength and moisture absorption of biocomposites increased.
Composites Part B-engineering, 2019
This paper presents the effect of compaction parameters on the permeability to resin, tensile and flexural performances of unidirectional (UD) composites made of UD flax-mat reinforcements. In these reinforcements the UD fiber yarns are held together by a thin mat layer of short flax fibers. Reinforcements were compacted in dry or wet conditions at ambient or high temperature prior to permeability testing and composites molding with the resin transfer molding (RTM) process. A micrographic analysis of the morphology and structure of the laminates prior to and after tensile testing was also performed. It is found that hot and wet compaction do not change the permeability. Moreover, after molding with compacted reinforcements, the tensile strength increases while the tensile modulus is not affected. It also leads to a substantial increase in the flexural properties (strength and modulus). This means the chosen compaction parameters are appropriate for preforming this type of reinforcement.
Macroscopic analysis of interfacial properties of flax/PLLA biocomposites
Composites Science and Technology, 2010
This study presents results from a study of the mechanical behaviour of flax reinforced Poly(L-Lactic Acid) (PLLA) under in-plane shear and mode I interlaminar fracture testing. Slow cooling of the unreinforced polymer has been shown to develop crystalline structure, causing improvement in matrix strength and modulus but a drop in toughness. The in-plane shear properties of the composite also drop for the slowest cooling rate, the best combination of in-plane shear performance and delamination resistance is noted for an intermediate cooling rate, (15.5°C/min). The values of G Ic obtained at this cooling rate are higher than those for equivalent glass/polyester composites. These macro-scale results have been correlated with microdroplet interface debonding and matrix characterization measurements from a previous study. The composite performance is dominated by the matrix rather than the interface.
Procedia CIRP, 2014
In this paper a new process to manufacture unidirectional reinforcements for eco-composite materials, made of natural fibers, is presented. Starting with flax rovings of different sizes, an apparatus was developed to feed and align the rovings over the wet-end section of a paper machine. The short kraft paper fibers are therefore mixed with the long flax roving as the machine is running, and at the end of the process, a sheet of the hybrid dry reinforcement is obtained and cut to size for impregnation with various resins, using different processes. This novel manufacturing process allows for high volume production of reinforcement. It is very flexible, and many different combinations of long and short fibers can be exploited for the production of a vast variety of dry reinforcements. In this paper, composite samples are obtained out of these reinforcements, using the resin infusion (RI) molding process with a commercial epoxy resin. The results are compared with those of usual glass fiber reinforcement. An interesting aspect is that the large variability, typical for natural fibers, is largely reduced when the short kraft fibers are present in the composite. In terms of permeability to resin, reasonably comparable values can be obtained compared to that of glass fabrics, if a low surface density of reinforcement is chosen.
Specific features of flax fibres used to manufacture composite materials
International Journal of Material Forming, 2018
The use of composite materials reinforced by flax fibres has been increasing steadily over the last 20 years. These fibres show attractive mechanical properties but also some particularities (naturally limited length, presence of a lumen, fibres grouped in bundles in the plant, complex surface properties and composition). An analysis of the available literature indicates that the quality of the composite materials studied is not always optimal (high porosity, incomplete impregnation, heterogeneous microstructure, variable fibre orientation). This paper reviews published data on the specific nature of flax fibres with respect to manufacturing of biocomposites (defined here as polymers reinforced by natural fibres). All the important steps in the process which influence final properties are analyzed, including the plant development, retting, fibre extraction, fibre treatment, preform preparation, available manufacturing processes, the impregnation step, fibre cell wall changes during processing and fibre/matrix adhesion.