Natural fibers microfibrils

The filaments of all plant fibers consist of several cells. These cells form crystalline microfibrils (cellulose), which are connected together into a complete layer by amorphous lignin and hemi-cellulose. Multiple layers stick together to form multiple layer composites, filaments. A single cell is subdivided into several concentric layers, one primary and three secondary layers. Figure 5 shows a jute cell. The cell walls differ in their composition and in the orientation of the cellulose microfibrils whereby the characteristic values change from one natural fiber to another. 

When reducing the fibers into microfibrils, the hierarchical structure of natural fibers is exploited and important craisequences occur. The first one is obviously an increase in the specific area of the particles, from values of approximately a few... 

The plant cell wall is the most important part of lignocellulosic natural fibers. Figure 1.4(c) shows the schematic representation of the natural plant cell wall [19]. The cell wall of lignocellulosic natural fibers primarily consists of a hollow tube with four different layers [19]. The first layer is called the primary cell wall, the other three, the secondary cell walls, while an open channel in the center of the microfibrils is called the lumen... 

Section 7.3, composites with natural fibers (e.g., cellulose, bamboo) and microfibril-reinforced polymer-polymer composites... 

Natural fibers of mineral origin are mainly used for industrial insulation purposes, whereas animal fibers are used for domestic insulation, clothing and carpets. The most beneficial fibers from the environmental point of view are those of vegetable origin. Natural fibers can be considered cellulose fibrils reinforced materials, which consist of microfibrils in an amorphous matrix of lignin and hemicellulose [28]. The cell wall in a fiber is not a homogenous membrane (Figure 4.1). 

Natural fibers consist of aggregated cellulose chains arranged in a hierarchical structure. These elementary fibrils are composed of cellulose chains called cellulose macro fibrils [16]. Figure 6.3 shows a fransmission elecfron microscopy (TEM) image of cellulose microfibrils, or MFC [17],... 

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