Physical Structure of Natural Polymer Fibers

The physical structure of natural cellulose and protein fibers is determined by the genetic codes. Hnman can only have limited inflnence on the physical stmcture of natural cellulose and protein fibers by selecting the species being raised and the enviromnental conditions snch as soil, water sonrce, farming method, etc. However, the physical stmctnre of mannfactured cellnlose and protein fibers can be manipulated by controlling the chemical stmcture and processing conditions. 

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The chemical and physical structures of natural polymer fibers are more complex than those of synthetic polymer fibers. Two most important building imits for natural polymer fibers are cellulose and protein. Natural cellulose fibers come from the stringy portions of plants ranging from the fine seed fibers of the cotton plant to the coarse pineapple leaf fibers. Natural protein fibers are hairs of animals, like the sheep and the dehcate filaments spun by silkworms and insects. In addition to these natural fibers, manufactured cellulose and protein fibers also are based on natural biopolymers. Although these fibers are processed like synthetic polymer fibers, they are discussed in this book together with natural cellulose and protein fibers since they have similar chemical structures. The chemical and physical structures of natural polymer fibers are discussed in Chapters 4 and 5, respectively. 

In the course of his studies of the dyeing process, he became deeply interested in the structure of natural fibers, and most of his efforts were directed toward this new field of research, with the help of able associates, among them R. Brill, M. Dunkel, G. von Susich, and E. Valkd. His investigation of various aspects of the problem utilized physical means (for example, x-ray diffraction, optical properties, and viscosity) and the purely chemical approach. A young scientist, H. Mark, who later became an authority in the field of high polymers, was appointed head of the physical chemistry laboratory. 

The more fundamental aspects of fiber constitution and behavior are dealt with in Astbury s Fundamentals of Fibre Structure 27) and Textile Fibres under the X-Rays 28), Hermans Contributions to the Physics of Cellulose Fibres 39), and Physics and Chemistry of Cellulose Fibres (40 Marsh s Textile Science (40 Preston s Fibre Science 59) and the High Polymers series of monographs, three of which are concerned with natural fibers—Volume IV, Natural and Synthetic High Polymers, by Kurt H. Meyer 53), Volume V, Cellulose and Cellulose Derivatives, edited by Emil Ott 56), and Volume VI, Mechanical Behavior of High Polymers, by Turner Alfrey, Jr. 21 ... 

It is well established that the supermolecular structure of semiciystalline matrix is of pivotal importance to the mechanical and physical behavior of composite materials. We analyzed the formation of the polymorphic forms in polypropylene composites with natural fibers. Moreover, analysis of the effect of processing conditions, during preparation of the composites, on the structure of polymer matrix is a focal issue because polymorphic changes in polypropylene can be stimulated by the temperature of processing and the shearing forces applied. 

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