| Green composites are currently the center of attention for most of the researchers worldwide due to the well-established mechanical properties, low density, cost effectiveness and biodegradability offered by natural fibers. Flaxseed straws, which are currently considered as a waste, can be a valuable and abundant resource as reinforcement fibers in green composite materials.This study involved two phases, in the first phase the alkaline treatment, chemical composition analysis and tensile property of the flaxseed fiber bundles were investigated for their potential useful applications in green composites. Second phase included the composite fabrication followed by testing of tensile and bending properties of the composites. Two methods were opted to treat flaxseed fiber bundles by using NaOH with the strengths of lOg/1and20g/1, resulting in22.2%and45.2%weight losses, respectively. The fibers were not separated sufficiently despite the higher weight loss, which indicated flaxseed fiber bundles were partially degummed. The SEM micrographs showed that alkali treatment resulted in improvement in the surface roughness and topography; with significantly better results in20g/L NaOH treated samples. Quantitative composition analysis further proved the different components percentage in flaxseed as compared to the common flax. The results showed Wax3.1%, Dissolvable Substances7.14%, Pectin6.3%, Lignin15.08%, Hemi-Cellulose28.27%and Cellulose40.11%. In comparison with the fiber flax, the impurities in flaxseed were found to be twice or more, however, the Cellulose was almost50%less. Bundle fiber test method was used to determine the strengths of untreated fibers and NaOH treated fibers. Evaluation of tensile property revealed acceptable results showing samples treated with10g/L NaOH (0.88cN/dtex) and20g/L NaOH (0.85cN/dtex) with almost25%decrease in strength as compared with the untreated samples (1.14cN/dtex). Effects of temperature and pressure on fiber bundle strength showed that pressure had minimum effect (8%), however, the temperature had very significant effect (40%) on the fiber bundle strength.These investigations provided the basis for choosing the appropriate matrix and method to fabricate composites using both untreated and treated fiber bundles with evaluation and comparison of their tensile, flexural and morphological properties. Polybutylene Succinate (PBS) with melting temperature of113℃was selected as a matrix. Compression molding method was used in the fabrication of composites. Single layered lamina and three layered (laminae) composites were fabricated with40%fiber loading. It was observed that untreated three layered laminae had higher average tensile strength (78MPa) as compared to untreated single lamina (56MPa) as well as three laminae NaOH10g/L treated (53.85MPa) and20g/L NaOH treated (54.29MPa). Outcomes of flexural property test were found to be for untreated (26.69MPa), NaOH10g/L (31.85MPa) and NaOH20g/L (42.69MPa), respectively. This illustrated that the20g/L NaOH laminae had better bending properties referring to its improved surface topography and roughness that resulted in better mechanical interlocking and interfacial properties between the fiber and the matrix. Depending on the criterion for the final composite application, untreated fiber bundles with higher strength and alkali treated fiber bundles with better bending properties can both be used as reinforcements in natural fiber composites.This study provided significant fundamental data about the composition and properties of Flaxseed fiber bundles as well as Flaxseed/PBS composites that can prove very useful for their future potential applications in Natural Fiber Green Composite materials. |
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