The abundant availability and accessibility of plant fibres are the major reasons for an emerging new interest in sustainable technology. While focusing on the composite materials, the main points to be considered are environment friendliness and light weight, with high specific properties. This century has witnessed remarkable achievements in green technology in the field of materials science through the development of high-performance materials made from natural resources is increasing worldwide. Plant fibres are a kind of renewable resources, which have been renewed by nature and human ingenuity for thousands of years. The greatest challenge in working with plant fibre reinforced composites (PFRCs) is their large variation in properties and characteristics. A PFRCs properties are influenced by a number of variables, including the fibre type, environmental conditions, processing methods, and modification of the fibre. A detailed systematic review on these sustainable and renewable green materials is presented in this paper. The overall characteristics of plant fibres used in bio-composites, including source, type, structure, composition, as well as properties, will be reviewed. Finally, the review will conclude with recent developments and future trends of PFRCs as well as key issues that need to be addressed and resolved.

Plant fibre based bio-composites: Sustainable and renewable green materials

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 behavior of high performance natural (sisal) fibers

Mechanical and dynamic properties of coconut fibre reinforced concrete

Enhancement of tensile strength of lignocellulosic jute fibers by alkali-steam treatment.

The morphological, physical, and mechanical properties of the nonwood plant fiber bundles of ramie, pineapple, sansevieria, kenaf, abaca, sisal, and coconut fiber bundles were investigated. All fibers except those of coconut fiber had noncircular cross-sectional shapes. The crosssectional area of the fiber bundles was evaluated by an improved method using scanning electron microscope images. The coefficient factor defined as the ratio of the cross-sectional area determined by diameter measurement, to the cross-sectional area determined by image analysis was between 0.92 and 0.96 for all fibers. This indicated that the area determined by diameter measurement was available. The densities of the fiber bundles decreased with increasing diameters. The diameters of each fiber species had small variation of around 3.4%-9.8% within a specimen. The tensile strength and Young’s modulus of ramie, pineapple, and sansevieria fiber bundles showed excellent values in comparison with the other fibers. The tensile strength and Young’s modulus showed a decreasing trend with increasing diameter of fiber bundles.

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Characterization of the morphological, physical, and mechanical properties of seven nonwood plant fiber bundles

Understanding the basic properties of natural fibers is important to determine the optimal intended uses for instance as high-quality bio-composite raw material. This review describes the characteristics, and potential uses of some natural fibers in order to improve their sustainability and economic values. The natural fibers have low density and high strength to weight ratio and reduction make them potential as light weight composite and reinforcement materials. The microstructure and chemical compositions of fibers affect the mechanical properties with the fiber cross-sectional area is the most variable influencing the fiber strength. Natural fibers are easy to absorb water due to the presence of hemicellulose that give hydrophilic properties make them less compatible in the interaction with matrix with hydrophobicity properties. Higher cellulose content and crystallinity tend to result better strength properties of fiber while lignin is since versa. Besides that, fiber anatomical characteristics vary between different and same species that affect on the density and mechanical properties. The other factors namely environmental conditions, method of transportation, storage time and conditions, and fiber extraction affect the size and quality of the natural fibers.

A review on natural fibers for development of eco-friendly bio-composite: characteristics, and utilizations

The development of natural adhesives derived from nonfossil resources is very important for the future. Besides, it is desirable to be safe adhesives without using harmful chemical substances. In this study, application of citric acid as a natural adhesive was investigated. Citric acid powder and bark powder obtained from Acacia mangium were used as raw materials. Citric acid powder was mixed with the bark powder, and the resulting powder mixture was poured into a metal mold. The mold was hot-pressed at 180°C and 4 MPa for 10 min, and a bark molding was then obtained. The specific modulus of rupture and modulus of elasticity values of the molding containing 20 wt % citric acid were 18.1 MPa and 4.9 GPa, respectively. The molding did not decompose during a repeated boiling treatment. To clarify the effect of tannin on the adhesiveness of molding, bark was separated into tannin and residue. The molding was not obtained while using the tannin due to the marked fluidity, whereas it was obtained while using the residue, the same as while using the bark. It was considered that components other than tannin contributed to the adhesiveness. Based on the results of Fourier transform infrared spectra, the formation of ester linkages between carboxyl groups derived from citric acid and hydroxyl groups in the bark was confirmed. Accordingly, citric acid brought an adhesion by chemical bonding, and it could be used as a safe natural adhesive. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Application of citric acid as natural adhesive for wood

This study focused on the effects of treatments of alkali, mild steam, and chitosan on the surface morphology, fiber texture, and tensile properties of pineapple, ramie, and sansevieria fiber bundles. The fibers were treated with NaOH (2%), mild steam (0.1 MPa), and chitosan solutions (4% and 8%). The properties of these treated fibers were characterized and compared with the untreated fibers. Field emission scanning electron microscopy (FE-SEM) was used to observe the surface morphology of those fibers. X-Ray diffraction (XRD) spectroscopy was used to observe the fiber textures. Tensile properties of the treated and untreated fibers were also recorded. SEM micrographs showed that the surfaces of the NaOH-treated fibers were more damaged than those of the steam-treated fibers. The 4% chitosan solution covered the fiber surface more uniformly than the 8% chitosan solution. The steam-treated fibers had higher values of degree of crystallinity, crystallite orientation factor, and crystallite size than the NaOHtreated fibers. Ramie fiber showed greater mechanical properties than the other fibers. The values of tensile strength, Young’s modulus, and toughness of the steamtreated fibers, which were similar to those of the 4% chitosan-coated fibers, were higher than those for the other treatments.

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Effects of alkali, mild steam, and chitosan treatments on the properties of pineapple, ramie, and sansevieria fiber bundles

To utilize various potential agricultural residues, pellet making was performed and the pellets obtained were characterized in this study. Oil palm empty fruit bunch (OPEFB), oil palm frond (OPF), oil palm shell (OPS) and oil palm mesocarp (OPM) were employed as feedstock. Biopellet production was started with material crushing to get uniform material and then continued with pellet forming. Pellet making was conducted using conventional pelletizer under temperatures of 150, 200 and 250 °C for 15 minutes. Some characteristics were measured to determine biopellet quality, i.e. moisture content, density, ash content and calorific value. Based on the water content, ash content, density and calorific value, OPM biopellets that pressed at 200 and 250 °C showed the best formula. The characteristics of this biopellet were moisture content of 1.7-1.9%, ash of 6.85-7.45%, and calorific value of 3,814-4,724 kcal/kg.

Sasa Sofyan Munawar

Papers

Characterization of the morphological, physical, and mechanical properties of seven nonwood plant fiber bundles

A review on natural fibers for development of eco-friendly bio-composite: characteristics, and utilizations

Application of citric acid as natural adhesive for wood

Effects of alkali, mild steam, and chitosan treatments on the properties of pineapple, ramie, and sansevieria fiber bundles

Characterization of Biomass Pellet Made from Solid Waste Oil Palm Industry