Natural fiber composites additives

Recent basic research has turned up new approaches for innovative materials combining elements of, and integrating the advantages of, wood and synthetic plastics. Lignin is one of the main components of this new class of plastic-like, wood-like biocomposites. The resulting mixture of lignin, natural fibers, and additives is a compound processable as a thermoplastic. The processed materials are short fiber composites. Arboform is a trade name for this class of compounds. 

TGA is a thermal method that measures the weight loss as a function of temperature or time. Polypropylene decomposes at a lower temperature than polyethylene because of the substitution of a methyl group. Some works showed an increase of the degradation temperature of composites with the addition of carbon nanotubes and other synthetic fibers [52]. PE with natural fiber composites show two steps degradation processes because of cellulose, Thermal stability of PE/cellulosic fiber composites decreases with increase in fiber loading, showing two degradation processes. However,... 

Additionally, the dependence of the mechanical properties on humidity is clearly reduced because of the moisture repellency of glass fibers [69]. The moisture absorption of composites is clearly smaller when natural fibers are replaced by glass fibers [65]. 

Proper characterization of composite interfaces, whether it is for chemical, physical or mechanical properties, is extremely difficult because most interfaces with which we are concerned are buried inside the material. Furthermore, the microscopic and often nanoscopic nature of interfaces in most useful advanced fiber composites requires the characterization and measurement techniques to be of ultrahigh magnification and resolution for sensible and accurate solutions. In addition, experiments have to be carried out in a well-controlled environment using sophisticated testing conditions (e.g. in a high vacuum chamber). There are many difficulties often encountered in the physico-chemical analyses of surfaces. 

Throughout this chapter the chemical concepts employed to synthesize and cure addition poly(imides) have been discussed and their use as matrix resins for fiber composites has frequently been mentioned. The most important property of the imide backbone structure is the inherent thermal stability. The target of achieving the temperature performance of linear poly(imide) has not been reached, because of the aliphatic nature of the reactive endgroups, and because of the low molecular weight of the imide backbone required for processing. Future developments of addition polyimides will, as in the past, focus on the requirement of high thermal and thermal oxidative stability of the crosslinked... 

W. Sigworth, L. Walp, R. Bacaloglu, and P. Kleinlauth. The role of additives in formulating WPC. In The Global Outlook for Natural Fiber Wood Composites 2003, New Orleans, LA, December 3-5, 2003. Principia Partners, 7th International Conference of Wood-Fibre Plastic Composites, Madison, WI, May 19-20, 2003. 

M. Manning. Borates as biocidal additives for WPC. In The Global Outlook for Natural Fiber and Wood Composites 2003, New Orleans, LA, December 3-5, 2003. 

G. Capocci, U. Stadler, and M. Reyes. Anti-staining and anti-fungal additives for wood-fiber-plastic composites. In Conference Proceedings of the Global Outlook for Natural Fiber Wood Composites 2004, Intertech, Portland, ME, New Orleans, LA, December... 

Natural fibers can be classified as seed fibers (such as cotton), bast fibers (like flax, hemp, jute, kenaf, ramie), hard fibers (like sisal), fi-uit fibers (like coir), and wood fibers. The chemical composition and dimensions of some common agro-fibers are presented in Table 5.21. The origin of wood fibers can be sawmill chips, sawdust, wood flour or powder, cutter shavings, pulp or wood residues. As binders for these fibers, both thermosetting (like phenolic, epoxy, polyester) resins and thermosetting matrices [such as polyethylene (LDPE, HDPE), polypropylene (PP), poly(vinyl chloride) (PVC), polystyrene (PS)j can be used. Thermoplastic composites are, however, less expensive to process than thermosetting composites, in addition to their ability to be manufactured into complex shapes. 

Cellulose represents an important polymer, which is most abundant in nature, and serves as a renewable resource in many applications, e.g., fibers, films, paper, and as a composite with other polysaccharides and lignin in wood. Cellulose derivatives will also be used as films and fibers, food additives, thermoplastics, and construction materials, to name just a few. Cellulose and cellulose derivatives have played an important role in the development of the macromolecular concept. So far, little use has been made of the fact that cellulose represents a chiral material except, e.g., in a rare case as stationary material in liquid chromatography for the separation of chiral compounds. Nature ifself uses the chirality of cellulose occasionally, and twisted structures of cellulose molecules are found in cell walls. 

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