ABSTRACT
Thermal denaturation of natural bers occurs when they are heated. At temperatures above 180ºC, hemicellulose, lignin, protein, and sugar content make reactions such
6.1 Introduction .................................................................................................. 157 6.2 Factors Affecting the Processing of Natural Fiber Composites ................... 157 6.3 Processing Method for Natural Fiber Composites ....................................... 159 6.4 Preparation of Natural Fibers ....................................................................... 159 6.5 Effects of Processing Temperature on Mechanical Properties of Natural
Fiber Composites .......................................................................................... 162 6.6 Effect of Fiber Orientation Factor on the Mechanical Properties in
Natural Fiber Composites ............................................................................. 165 6.6.1 Calculation ........................................................................................ 166 6.6.2 Effect of Fiber Orientation Distribution on Flexural Modulus......... 169
6.7 Conclusions ................................................................................................... 172 References .............................................................................................................. 172
as condensation, oxidation, and reduction, changing the color of the ber from white to brown and degrading the strength of the nal composites. Further, at temperatures above 250ºC, the bers degrade at the point of their carbonization, turning the color of the composites into black. For these reasons, the temperature control at the time of mixing and molding is important. The same reactions described earlier affect the natural ber at the time of its preparation, that is, just after they are harvested, natural bers contain water, sugar, oil, and protein; it is better for some of them to be removed before processing, otherwise their presence may possibly decrease the processing temperature. Alkali treatment is also effective in improving the adhesion between the ber and the matrix [6-7].
