Minimizing Property Variation in Natural Fiber Reinforcements for Green Composite Materials Applications

Abstract:

Properties of composite materials are often predicted from properties of its component materials. In the case of green composites that are typically filled with natural fibers however, a large deviation from predictions is observed due to the large property variation in natural fibers. In this study, techniques have been developed to minimize the effect of the said variations, which included the determination of a fiber useful length and critical length, and the utilization of controlled chemical treatment to remove unwanted fiber components that interfere in fiber-matrix interfacial bonding. The abaca fiber was determined to have a diameter of 190 + 2 mm in about two-thirds of the fiber length in the middle section. A large variation in fiber diameter was observed at the root and tip sections such that the diameter could be as high as 200 mm at the root while the tip tapers to 110 to 165 mm. The useful length with constant diameter was determined to be about 2000 mm at the middle section. The critical length of this useful length was found to be 3.15 mm. The tensile strength was also determined to have an average of 970 MPa when measured at 15 mm gauge lengths but is found to decrease up to 796 MPa with increasing gauge lengths up to 35 mm. This superior tensile strength of abaca is also associated to the 2-3^o microfibril misorientation from the axis of the fiber. Use of the fibers in composite as continuous and unidirectional filler at 5% loading to unsaturated polyester (tensile strength of 40 MPa) resulted to a tensile strength of 48 MPa. The tensile strength increased to 71 MPa when chemically treated continuous fiber was employed. Alkali treatment at relatively high temperature improved the surface morphology of the fiber, with waxes and lignin removed from the surface and activating the surface with hydroxyl functional groups, that essentially improved the wettability of the polymer to the fiber, and densified the fiber with the closure of its lumens.

• Periodical: Materials Science Forum (Volume 894)
• Pages: 50-55
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.894.50
• Online since: March 2017
• Authors: Leslie Joy L. Diaz*, Stella Marie Hagad, Peter June M. Santiago
• Keywords: Chemical Treatment, Critical Length, Interfacial Bond, Natural Abaca Fibers, Weibull Parameter

References

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[3] S.M. Hagad. Effect of Fiber Chemical Modifications on the Abaca Fiber-Reinforced Unsaturated Polyester Matrix. MS Thesis 2009. University of the Philippines, Diliman.

[4] P. Ghosh. Fibre Science and Technology: Chapter 2-Natural Fibers. (2004).