Mechanical properties of alkali treated plant fibres and their potential as reinforcement materials. I. hemp fibres

• Published in: Journal of materials science Vol. 41; no. 8; pp. 2483 - 2496
• Main Authors: MWAIKAMBO, L. Y, ANSELL, M. P
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-04-2006; Springer Nature B.V
• Subjects: Applied sciences; Aramid fibers; Bundles; Bundling; Caustic soda; Cellulose; Cellulose fibers; Compounding ingredients; Crystal structure; Crystalline cellulose; Crystallinity; Exact sciences and technology; Fibers; Fibres; Fillers and reinforcing agents; Fine structure; Hemp; Kevlar (trademark); Materials science; Mechanical properties; Modulus of elasticity; Polymer industry, paints, wood; Reinforcement; Sodium hydroxide; Stiffness; Synthetic fibers; Technology of polymers; Tensile strength; Topography; Vegetable fibers; Hemp; Reinforcing filler; Synthetic fiber; Plant fiber; Mechanical properties; Chemical base; Crystallinity; Experimental study; Tensile strength; Surface treatment; Sodium hydroxide; Structure processing relationship; Natural fiber; Morphology; Property structure relationship; Comparative study
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-006-5098-x

In this study a thorough analysis of physical and fine structure of hemp fibre bundles, namely surface topography, diameter, cellulose content and crystallinity index, have been presented. The fibre bundles have been alkalised and physical and mechanical properties analysed. Alkalisation was found to change the surface topography of fibre bundles and the diameter decreased with increased concentration of caustic soda. Cellulose content increase slightly at lower NaOH concentrations and decrease at higher NaOH concentrations. The crystallinity index decrease with increase in caustic soda concentration up to 0.24% NaOH beyond which, it decreases with increase in NaOH concentration. It was also found that the tensile strength and stiffness increases with increase in the concentration of NaOH up to a limit. Tensile strength and Young’s modulus increase with decrease in cellulose content, while crystalline cellulose decreases slightly but with improved crystalline packing order resulting in increased mechanical properties. Similar observations are elucidated by the crystallinity index. Alkalised hemp fibre bundles were found to exhibit a similar specific stiffness to steel, E-glass and Kevlar 29 fibres. The results also show that crystallinity index obtained following alkalisation has a reverse correlation to the mechanical properties. Stiffer alkalised hemp fibre bundles are suitable candidates as reinforcements to replace synthetic fibres. The improvement in mechanical properties of alkali treated hemp fibre bundles confirms their use as reinforcement materials.