Wood-polymer composites compounding

These materials are from renewable sources and are often made from plant materials that can be grown year after year and should come from agricultural nonfood crops. Biodegradable polymers are broken down into CO 2 and water by microorganisms. Although biopolymers may be able to help solve the disposal problems of current plastic packaging, it is not clear if they can really deliver on this promise and whether there is possible competition with the food chain. Cellulose is the most common biopolymer and organic compound on Earth. Other examples are starch, PHB (polyhydroxybutyrate), natural fibers, silk, and wood plastic composites (WPC). 

It has been found that IR imaging enables visualizing the distribution of not only wood compounds but also wood particles in the polymer matrix within wood-plastic composites (Figure 6.17) [107]. The interaction at the interphase between wood and polymers, glue, or paint is often critical for product performance and can be investigated accurately using IR spectroscopy [99]. 

Matuana, L.M., Kamdem, D.P., Zhang, J. Photoaging and stabilization of rigid PVC/wood-fiber composites. J. Appl. Polym. Sci. 80(11), 1943-1950 (2001) Chaochanchaikul, K., Rosarpitak, V., Sombatsompop, N. Photodegradation profiles of PVC compound and wood/PVC composites under UV weathering. Exp. Polym. Lett. 7(2), 146-160 (2013)... 

The first report of wood fiber composites being subject to microbial attack dates to 1998. " In this case, the matrix was HOPE. At about the same time, a report issued describing microbial attack on polyethylene membranes. It is likely that microbial metabolism was limited to additives in the film. There is, moreover, good evidence that, under ordinary conditions, PVC polymers are not metabolized by microbes. Composites made from the following compound were placed in contact with moist soil inoculated with a variety of fungi ... 

T. Akbulut, N. Ayrilmis, T. Dundar, A. Durmus, R. H. White, and M. Teker, Effect of boron and phosphate compounds on thermal and fire properties of wood/HDPE composites. International Journal of polymers and Technologies 3 (2), 67-75 (2011). 

The first synthetic plastics were the phenol-formaldehyde resins introduced by Baekeland in 1907 [1], Melamine and urea also react with formaldehyde to form intermediate methylol compounds which condense to cross-linked polymers much like phenol-formaldehyde resins. Paper, cotton fabric, wood flour or other forms of cellulose have long been used to reinforce these methylol-functional polymers. Methylol groups react with hydroxyl groups of cellulose to form stable ether linkages to bond filler to polymers. Cellulose is so compatible with these resins that no one thought of an interface between them, and the term reinforced composites was not even used to describe these reinforced systems. 

Heterogeneous composite materials made from waste or recycled components such as polyolefin polymers and wood fibers were shown to be made compatible by T. Czvikovszky through the use of small amounts of monomers that graft onto the two normally incompatible phases of said mixtures. These compositions demonstrated sufficient material properties to be used in the construction of truck and automotive components, such as door and side panels. To exploit the use of such recycled resources, process techniques in mixing and compounding had to be developed. 

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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