• Journal of the Korean Wood Science and Technology
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• v.24 no.3
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• pp.101-109
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• 1996

Effects of process variables were evaluated in physical properties of the wood fiber-thermoplastic fiber composites using nonwoven web method. Turbulent air mixer using compressed air was employed to mix wood fiber with two types of thermoplastic polypropylene and nylon 6 fibers. The optimal hot press temperature and time were found to be $190^{\circ}C$ and 9 minutes in wood fiber-polypropylene fiber composite and to be $220^{\circ}C$ and 9 minutes in wood fiber-nylon 6 fiber composite. As the density of wood fiber-polypropylene fiber composite and wood fiber-nylon 6 fiber composite increased, the physical properties were improved The density appeared to be the most significant factor on physical properties in the statistical analysis. The composition ratio of polypropylene or nylon 6 fiber to wood fiber was considered not to be statistically significant factor. The thickness swelling decreased somewhat in wood fiber-polypropylene fiber composite and wood fiber-nylon 6 fiber composite as the content of synthetic fiber increased. As the increase of mat moisture content, dimensional stability was improved in wood fiber-polypropylene fiber composite but not in wood fiber-nylon 6 fiber composite.

• Journal of the Korean Wood Science and Technology
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• v.25 no.3
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• pp.58-65
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• 1997

This research was carried out to evaluate the effect of process variables on mechanical properties of the wood fiber-thermoplastic fiber composites by turbulent air mixing method. The turbulent air mixer used in this experiment was specially designed in order to mix wood fiber and thermoplastic polypropylene or nylon 6 fiber, and was highly efficient in the mixing of relatively short plastic fiber and wood fiber in a short time without any trouble. The adequate hot - pressing temperature and time in our experimental condition were $190^{\circ}C$ and 9 minutes in 90% wood fiber - 10% polypropylene fiber composite and $220^{\circ}C$ and 9 minutes in 90% wood fiber 10% nylon 6 fiber composite. Both in the wood fiber - polypropylene fiber composite and wood fiber- nylon 6 fiber composite, the mechanical properties improved with the increase of density. Statistically, the density of composite appeared to function as the most significant factor in mechanical properties. Within the 5~15% composition ratios of polypropylene or nylon 6 fiber to wood fiber, the composition ratio showed no significant effect on the mechanical properties. Bending and tensile strength of composite, however, slightly increased with the increase of synthetic fiber content. The increase of mat moisture content showed no significant improvement of mechanical properties both in wood fiber - polypropylene fiber composite and wood fiber nylon 6 fiber composite. Wood fiber - nylon 6 fiber composite was superior in th mechanical strength to wood fiber-polypropylene fiber composite, which may be related to higher melt flow index of nylon 6 fiber(22g/10min) than of polypropylene fiber(4.3g/10min).

• Journal of the Korean Wood Science and Technology
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• v.26 no.2
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• pp.38-44
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• 1998

A new device that uses turbulent air for mixing wood fibers with thermoplastic fibers was designed and its mixing effectiveness was evaluated in wood fiber and polypropylene fiber composites. Composites made by the turbulent air mixing (TAM) process performed better than composites made by the conventional Rando-Webber forming or nonwoven web process with an additional needling step. Thus, the TAM process proved to be a simple and efficient method in mixing wood fibers with short thermoplastic fibers for the production of wood fiber and thermoplastic fiber composites.

• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.59-67
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• 2001

Rice husk flours were analyzed by chemical composition and thermogravimetric methods in nitrogen atmosphere to discuss its feasibility as a raw material for manufacturing agricultural lignocellulosic fiber-thermoplastic polymer composite. It was revealed in the chemical composition analysis that rice husk flour was composed of moisture, 5.0%; lignin, 21.6%; holocellulose, 60.8%; ash, 12.6%. In the thermogravimetric analysis (TGA), thermal decomposition behavior of rice husk flour from room temperature to $350^{\circ}C$ was similar to that of wood flour, but rice husk flour was more thermally stable from 350 to $800^{\circ}C$ than wood flour because of higher silica content in the rice husk flour and smaller particle size of rice husk flour. The activation energy of thermal decomposition was evaluated using Flynn & Wall expression. As the thermal decomposition proceeded in rice husk flour, the activation energy of thermal decomposition appeared almost constant up to ${\alpha}=0.25$, but thereafter increased. Activation energy of thermal decomposition in wood flour, however, decreased steeply up to ${\alpha}=0.3$, but thereafter remained almost constant. From the results, rice husk flour was thought be a substitute for wood flour in manufacturing agricultural lignocellulosic fiber-thermoplastic polymer composite in the aspect of thermal decomposition.

• Journal of Adhesion and Interface
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• v.3 no.4
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• pp.44-52
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• 2002

Composite materials are created by combining two or more component to achieve desired properties which could not be obtained with the separate components. The use of reinforcing fillers, which can reduce material costs and improve certain properties, is increasing in thermoplastic polymer composites. Currently, various inorganic fillers such as talc, mica, clay, glass fiber and calcium carbonate are being incorporated into thermoplastic composites. Nevertheless, lignocellulose fibers have drawn attention due to their abundant availability, low cost and renewable nature. In recent, interest has grown in composites made from lignocellulose fiber in thermoplastic polymer matrices, particularly for low cost/high volume applications. In addition to high specific properties, lignocellulose fibers offer a number of benefits for lignocellulose fiber/thermoplastic polymer composites. These include low hardness, which minimize abrasion of the equipment during processing, relatively low density, biodegradability, and low cost on a unit-volume basis. In spite of the advantage mentioned above, the use of lignocellulose fibers in thermoplastic polymer composites has been plagued by difficulties in obtaining good dispersion and strong interfacial adhesion because lignocellulose fiber is hydrophilic and thermoplastic polymer is hydrophobic. The application of lignocellulose fibers as reinforcements in composite materials requires, just as for glass-fiber reinforced composites, a strong adhesion between the fiber and the matrix regardless of whether a traditional polymer matrix, a biodegradable polymer matrix or cement is used. Further this article gives a survey about physical and chemical treatment methods which improve the fiber matrix adhesion, their results and effects on the physical properties of composites. Coupling agents in lignocellulose fiber and polymer composites play a very important role in improving the compatibility and adhesion between polar lignocellulose fiber and non-polar polymeric matrices. In this article, we also review various kinds of coupling agent and interfacial mechanism or phenomena between lignocellulose fiber and thermoplastic polymer.