In this work, kenaf fibers were pre-treated in a NaOH solution (6% in weight) at room temperature for two different periods (48 and 144 h). The chemical treatment of kenaf fibers for 48 h allowed to clean their surface removing each impurity whereas 144 h of immersion time had detrimental effect on the fibers surface and, consequently, on their mechanical properties. Untreated and NaOH treated kenaf fibers (i.e. for 48 h) were also used as reinforcing agent of epoxy resin composites. The effect of the stacking sequence (i.e. using unidirectional long fibers or randomly oriented short fibers) and the chemical treatment on the static mechanical properties was evaluated showing that the composites exhibit higher moduli in comparison to the neat resin. As regards the strength properties, only the composites reinforced with unidirectional layers show higher strength than the neat resin. Moreover, the alkali treatment increased the mechanical properties of the composites, due to the improvement of fiber–matrix compatibility. The dynamic mechanical analysis showed that the storage and the loss moduli are mainly influenced by the alkali treatment above the glass transition temperature. Moreover, the alkali treatment led to a notable reduction of tan  δ peaks in addition to significant shifts of tan  δ peaks to higher temperatures whereas the stacking sequence did not influence the trends of storage modulus, loss modulus and damping of the composites.

The effect of alkaline treatment on mechanical properties of kenaf fibers and their epoxy composites

The quest for sustainability in construction material usage has made the use of more renewable resources in the construction industry a necessity. Plant-based natural fibres are low cost renewable materials which can be found in abundant supply in many countries. This paper presents a summary of research progress on plant-based natural fibre reinforced cement-based composites. Fibre types, fibre characteristics and their effects on the properties of cement-based materials are reviewed. Factors affecting the fresh and hardened properties of cement-based composites reinforced with plant-based natural fibre are discussed. Measures to enhance the durability properties of cement-based composites containing plant-based natural fibres are appraised. Significant part of the paper is then focused on future trends such as the use of plant-based natural fibres as internal curing agents and durability enhancement materials in cement-based composites. Finally, applications and recommendations for future work are presented.

Plant-based natural fibre reinforced cement composites: A review

Tensile properties of kenaf fiber due to various conditions of chemical fiber surface modifications

Abaca fibers demonstrate enormous potential as reinforcing agents in composite materials. In this study, abaca fibers were immersed in 5, 10 or 15 wt.% NaOH solutions for 2 h, and the effects of the alkali treatments on the mechanical characteristics and interfacial adhesion of the fibers in a model abaca fiber/epoxy composite system systematically evaluated. After 5 wt.% NaOH treatment, abaca fibers showed increased crystallinity, tensile strength and Young’s modulus compared to untreated fibers, and also improved interfacial shear strength with an epoxy. Stronger alkali treatments negatively impacted fiber stiffness and suitability for composite applications. Results suggest that mild alkali treatments (e.g. 5 wt.% NaOH for 2 h) are highly beneficial for the manufacture of abaca fiber-reinforced polymer composites.

Effect of alkali treatment on interfacial bonding in abaca fiber-reinforced composites

Effect of fiber treatment on flexural properties of natural fiber reinforced composites: A review

Environmentally beneficial composites can be made by replacing synthetic fibers with various types of cellulosic fibers. Fibers from pine wood, coir, sisal, abaca, coir, etc. are all good candidates. The most important factor in finding good fiber reinforcement in the composites is the strength of adhesion between matrix polymer and fiber. Due to the presence of hydroxyl groups and other polar groups in various constituents of abaca, the moisture absorption is high, which leads to poor wettability and weak interfacial bonding between fibers and the more hydrophobic matrices. Therefore, it is necessary to impart a hydrophobic nature to the fibers by suitable chemical treatments in order to develop composites with better mechanical properties. In the present work, the effect of alkali treatment on the moisture absorption tendency of single abaca fiber was investigated. The results shown that the alkali treated fiber absorbs less moisture than the untreated raw fiber.

https://ojs.cnr.ncsu.edu/index.php/BioRes/article/download/BioRes_07_3_3515_Punyamurthy_SSB_Alkali_Absorption_Abaca_Fiber/1614

Effect of alkali treatment on water absorption of single cellulosic abaca fiber

Untreated abaca fibers and benzenediazonium chloride treated abaca strands were employed as reinforcements for fabricating polypropylene composites by injection molding method. Various composites were fabricated with different fiber loadings of 30%, 35%, 40%, 45% and 50% with and without coupling agents. Abaca composites without coupling agents with 40% fiber loadings were found to have optimum properties when mechanical characterization was done and the investigation also revealed that untreated and treated composites with coupling agents were found to have improved tensile strength, flexural strength and impact strength when correlated to composites without coupling agents. Among various surface modifications performed, benzenediazonium chloride treated abaca strands reinforced polypropylene composites with coupling agents showed superior properties. For composites including coupling agents, surge in tensile strength and flexural strength was observed with hike in fiber content up to 50% whereas optimum impact properties were shown at 40% fiber loading. Between untreated composites with coupling agent and without coupling agent, composites with coupling agent showed 77.50% hike in tensile strength for 50% fiber loading. Benzenediazonium chloride treated composites with coupling agent showed 70.07% increase in tensile strength when compared to benzenediazonium chloride treated composites without coupling agent for 50% fiber loading. Untreated composites with coupling agent showed 64.91% increase in flexural strength when compared to untreated composites without coupling agent for 50% fiber loading. Benzenediazonium chloride treated composites with coupling agent showed 36.84% increase in flexural strength when compared to benzenediazonium chloride treated composites without coupling agent for 50% fiber loading. However, in case of impact strength, addition of coupling agent increased the impact strength up to 35% fiber loading and beyond 35% fiber loading addition of coupling agent decreased the impact strength. Untreated composites with coupling agent showed 3.53% decrease in impact strength when compared to untreated composites without coupling agent for 40% fiber loading. Benzenediazonium chloride treated composites with coupling agent showed 6.59% decrease in impact strength when compared to benzenediazonium chloride treated composites without coupling agent for 40% fiber loading.

Mechanical properties of abaca fiber reinforced polypropylene composites: Effect of chemical treatment by benzenediazonium chloride

A study has been carried out to evaluate physical and flexural properties of composites made by areca fibers with a randomly distributed orientation of fibers. The extracted areca fibers from the areca husk were alkali treated with potassium hydroxide (KOH) to get better interfacial bonding between fiber and matrix. Then composites were developed by means of a compression molding technique with varying process parameters, such as fiber condition (untreated and alkali treated), and fiber loading percentages (50% and 60% by weight). The developed areca fiber reinforced composites were then characterized by physical and flexural tests. The results show that flexural strength increases with increase in the fiber loading percentage. Compared to untreated fiber, significant change in flexural strength has been observed for treated areca fiber reinforcement.

https://ojs.cnr.ncsu.edu/index.php/BioRes/article/download/BioRes_05_3_1846_Chikkkol_BKR_Flexure_Areca_Composites/682

Flexural behaviour of areca fibers composites

Environmentally beneficial composites can be made by replacing synthetic fibers with various types of cellulose fibers. The most important factor in finding good fiber reinforcement in the composite is the strength of adhesion between matrix polymer and fiber. Due to the presence of hydroxide and other polar groups in various constituents of natural fiber, the moisture absorption is high which leads to poor wettability and weak interfacial bonding between fibers and the more hydrophobic matrices. Therefore, it is necessary to impart hydrophobic nature to the natural fibers by suitable chemical treatments in order to develop composites with better mechanical properties. In the present work, the effect of esterification on the moisture absorption property of single areca fiber has been investigated.

/pdf/effect-of-esterification-on-moisture-absorption-of-single-1mjb76y2xu.pdf

Effect of esterification on moisture absorption of single areca fiber.

Environmentally valuable composites would be made by replacing synthetic fibers with various types of natural cellulose fibers. The most significant factor in finding good fiber reinforcement in the composite is the strength of the bond between matrix polymer and fiber. Due to the presence of hydroxide and other polar groups in various constituents of natural fiber, the moisture absorption is high which leads to poor wettability and weak interfacial bonding between fibers and the more hydrophobic matrices. Therefore, it is necessary to impart hydrophobic nature to the natural fibers by suitable chemical treatments in order to develop composites with better mechanical properties. In the present work, the effect of esterification on moisture absorption of single abaca fiber has been investigated. It was observed that the esterification process drastically reduced the moisture uptake of fibers. Acrylic acid treated abaca fiber showed about 32.87, 32.53, 50.76 and 39.01% lower moisture absorption than untreated fiber in pond water, river water, borewell water and sea water respectively.

/pdf/influence-of-esterification-on-the-water-absorption-property-1ey1yoxrjv.pdf

Basavaraju Bennehalli

Papers

Effect of alkali treatment on water absorption of single cellulosic abaca fiber

Mechanical properties of abaca fiber reinforced polypropylene composites: Effect of chemical treatment by benzenediazonium chloride

Flexural behaviour of areca fibers composites

Effect of esterification on moisture absorption of single areca fiber.

Influence of Esterification on the Water Absorption Property of Single Abaca Fiber