Natural fiber composites particle size

Similar result were obtained when the oil palm wood flour (OPWF) was mixed with epoxidized natural rubber (ENR). The increase of OPWF content resulted in the decrease of tensile strength and elongation at break of the OPWF/ENR composites. However, it increased tensile modulus, tear strength and hardness. Moreover, the cure (t ) and scorch time decreased when the OPWF content increased. Larger particle size of OPWF resulted in shorter t and scorch time, while the highest fiber content with the smallest particle size resulted in the highest torque [27]. 

Attractions have been drawn towards the improvement of natural fiber-reinforced composites properties. More extensive results have been published on the effect of fiber characteristics on properties [22, 23]. The debonding of excessive sized particles and their premature failure is reported to be common. In addition, thin fibers easily break... 

Toledo Filho et al. [32] studied the effect of a series of treatments on natural fiber and cement matrix in order to increase durability of cement mortars reinforced with sisal fibers. Based on results from their investigation, it was concluded that incorporation of sisal fibers significantly reduced mechanical properties of composite material. However, the mechanical properties of composite were maintained over time if the sisal fibers were immersed in a suspension of silica fume. This is because the silica fume particles contact the fiber and their size allows them to be located in smaller defects in the fiber, preventing that compounds such as calcium hydroxide, come into contact with the fiber and destroy it by growth of crystals. 

Another method to improve the mechanical properties such as interfacial strength is to add nanosized carbon fiber-reinforced particles into the composite [18-20]. A strong influence of a uniform dispersion of the small-sized fibers or partides on the composite properties of advanced nanocomposites, such as carbon nanotube-reinforced composites was also reported [21-24]. However, few papers mention the enhancing method for improving the interfacial adhesion between fiber and matrix in a natural BF composite. 

As such wood flour, used as a filler in thermoplastic composites, offers only modest, if any, reinforcement, but wood fibers can lead to superior composite properties and act more as reinforcing filler. Commercial wood flour is a by-product of the wood industry, often mechanically processed from waste materials such as planer shavings, chips, and sawdust, which are reduced to fine powders, with various grades available depending upon the particle size and the wood species. Wood (cellulose) fibers are produced through more or less complex defibrillation techniques, using raw materials from both virgin and recycled resources, and are different from natural fibers, such as jute, hemp, or sisal. 

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