Dimensional Analysis and Surface Morphology as Selective Criteria of Lignocellulosic Fibers as Reinforcement in Polymeric Matrices

Abstract

In recent years, there has been a resurgence of interest for the use of renewable materials such as plant fibers, also called ``lignocellulosic fibers'', due to increasing environmental concerns along with the unique characteristics of these fibers. These include abundant availability, renewability, biodegradability, as well as low wear and tear of equipments, particularly when processing their composites. In comparison with today's most used synthetic fibers such as glass fiber, lignocellulosic fibers offer the advantage of lesser health hazards and of course lower cost. In addition, they help in generating employment, particularly in rural sector, by leading to better living standards of the rural population. Thus, the utilization of these fibers has both short-term objectives, through the synthesis and characterization of composites, and long-term objectives, to use them as alternates for synthetic fibers and possible substitute for wood. This has driven the researchers to bring out data on the source and availability of all the useful lignocellulosic fibers, cataloging their available information on morphology and properties as well as current uses. A sound knowledge of the morphology of these fibers helps the understanding of their observed properties in terms of structural parameters, such as number, size, and shape of cells, chemical constituents, as well as the fracture mechanism in these fibers. Further, a careful examination of various properties of these fibers indicates that they are inconsistent probably due to the nonuniformity in dimensions and the defects in these fibers. The latter may be present either inherently or due to their processing. As a consequence, highly scattered properties are observed, which may be one of the drawbacks for their use as engineering materials. These limitations could, in principle, be overcome through an individual selection of fibers with approximately the same dimensions and properties by knowing the nature of correlation of fiber dimensions with a given property whereby the strongest fibers based on selection of their diameters could be separated. However, this may pose some problem with tedious work. Development of a scientific methodology does become essential to the selection of these fibers particularly for their application as reinforcements in various matrices to render them reliable, similar to synthetic fiber products.