#2: Alkali Treatment of bamboo fibers скачать в хорошем качестве

#2: Alkali Treatment of bamboo fibers

Alkali treatment or mercerization using sodium hydroxide (NaOH) is the most commonly used treatment for bleaching and cleaning the surface of the natural fibers to maximize the efficiency of the fiber reinforcement. Sodium hydroxide, also known as lye or caustic soda, has the molecular formula NaOH and is a highly caustic metallic base and alkali salt. Pure sodium hydroxide is a whitish solid, which is available in pellets, flakes, granules, and as a 50% saturated solution. Sodium hydroxide is soluble in water, ethanol and methanol. This alkali is deliquescent and readily absorbs moisture and carbon dioxide in air. Although molten sodium hydroxide possesses properties similar to those of the other forms, its high temperature comparatively limits its applications. Sodium hydroxide is used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents. In this work we used NaOH in pellets form, purchased from addis ababa carqos local suppliers with the brand name and code of RANKEM, S0290 respectively and performed chemical treatment of bamboo fiber Bamboo fibers exhibit a high level of moisture absorption and poor wetta bility, as a result the bamboo composite shows poor in adhesion at the fiber–matrix interface, leading to deboning of the fiber under a certain loading. This prevents the applied load from being transferred effectively from matrix to the fiber. Hence, interfacial adhesion and surface modification of such fibers is improved by employing alkali solution. This process is undertaken by removing of the amorphous regions of raw cellulose fiber, hemicelluloses, lignin, and pectin using alkali solution. In general, removal of these fatty like components from sisal and bamboo fibers leads the fibers to: Improve an adhesive properties for fiber–matrix interface; Improve fiber’s shear strength; Improve fiber’s rigidity and stiffness; Improve moisture absorption problems; Reduce fiber’s weight etc However, as concentration of NaOH increased the result obtained worsened the mechanical properties of the fibers. For this reason, after several trials, medium concentration of NaOH (i.e. 5%) is used for bamboo fiber and concentration of NaOH (i.e. 8%) for sisal fiber is used for this work. In general, this study consumed 1500 grams of NaOH pellets. Eq.3.1and 3.2 shows the chemical reaction between bamboo fiber and sisal fiber with aqueous sodium hydroxide solution respectively. Bamboo fiber-OH +NaOH → BAMBOO FIBER-O-Na+ + H2O (3.1) Sisal fiber-OH +NaOH → SISAL FIBER-O-Na+ + H2O (3.2) The treatment and mat preparation process is concisely summarized as follow. First, prepare bamboo and sisal fiber bundles. Then prepare 5% and 8% concentration of NaOH solution for bamboo and sisal fiber respectively. Next the fibers are soaked at room temperature in NaOH solution for 4 and 8 hour for sisal and bamboo fiber respectively. Then, the fiber washed many times with distilled water in order to neutralize it. Then after this the bamboo fiber is re-combed many times using wire brushes until 170-300μm diameters of individual fibers attained. Finally these fibers dried in sunlight for fifteen days. After the fiber dried, the plies prepared in 00 and 900 orientations as a unidirectional layers. In order to keep the fiber’s position while sewing individual fibers, different materials such as plastic scotch, sewing machine, angle and dimension measuring instruments, etc., are used.