Development of green composites using thermoplastics and bamboo fiber

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Bamboo fibers were extracted from raw bamboo such as Moso (Chinese) and Madake (a typical Japanese bamboo) by following three methods. (1) Mechanical processing by using the conventional fiber loosening machine. It has a rotating nail drum where thin bamboo strips are used. Younger bamboo than one year old is suitable for this method. (2) Alkali (NaOH) treatment: First, bamboo strips are immersed in a hot alkali bath for a couple hours, then, they are machined(3) Steam explosion method: Raw bamboo is set in a steam chamber which will be filled with super heated steam at high pressure. Then, the steam is abruptly released. Micro-cell explosion occurs in cells. Then, fibers are extracted by using the loosing machine from steam exploded bamboo. Relatively long fibers are obtained by the alkali treatment and the steam explosion method while short fibers are extracted when bamboo is mechanically processed. However, long fibers can be obtained enough to be used for fabricating non-woven fa … More brics by mixing thermoplastic (TP) fibers as long as the bamboo is very young. Non-woven fabrics using relatively short bamboo fibers as well as TP fibers such as PP and PE were successfully developed. It can be used as a green composite material to form inner components of automobiles such as ceiling and rear trays. PIA (Poly Lactic Acid) fibers made from corns can also be used instead of PP fibers. Fibers shorter than 50 mm are mixed with TP using a twin screw extruder to fabricate green composites pellets. In order to increase the tensile/bending strengths of the injection molded parts, the bamboo fiber diameter is a key as well as the aspect ratio. Thinner than 0.1 mm is desirable for the nominal diameter of bamboo fibers as well as a high aspect ratio greater than 20. Through the twin extruder path, the aspect ratio of bamboo fibers in a composite decreases. The maximum tensile strength of a bamboo fiber (50%wt content) /PP composite is about 50 Mpa. The maleic acid modification is obliged to increase the mechanical properties of bamboo fiber green composites.The mechanical properties of random bamboo fiber mats/Polyester composites (BFRP) were measured. The BFRP was fabricated by RTM (Resin Transfer Molding) while long bamboo fibers were extracted from MOSO bamboo by the alkali treatment. The bamboo mats were fabricated by using a carding machine in conjunction with a needle punching machine. The mats was very thick and the resultant BFRP had a low strength not enough to use for fabricating small boats (5 m long). Then, in order to increase the bamboo fiber fraction, bamboo mats were compressed in advance and used. The observed strength of the improved BFRP is strong enough to use for the boats. However, the study on water absorption tells us to pay a lot of attention on water. An appropriate treatment to prevent the water absorption during service is strongly suggested.The present study shows that not only the mechanical properties of PIA but also the heat resistance at elevated temperature are well improved due to inclusion of micro-fibrillated bamboo fibers. Short bamboo fibers can enhance the tensile strength and heat resistance, but the impact strength becomes low due to bamboo fibers. On the other hand, if the bamboo fibers are slightly fibrillated, the impact strength is well improved. Finally, the mechanical and thermal properties of the composite materials based on PLA are sometimes higher than those of 20 wt% glass fiber/ABS composite. The fibrillated bamboo fibers are also applied to fabricate the proving disks for semi-conductors. Less