Study On Refining Properties Of Kraft Bamboo Pulp

Because of shortage of forest resources, the supply of raw materials havebecome tight in China. Chinese have a small amount of wood pulp, but morenon-wood pulp. The main non-wood pulp are the rice straw pulp, wheat strawpulp, bamboo pulp, bagasse pulp and reed pulp. China has abundant bambooresources, the area of bamboo is about5.381million hectares, accounting for aquarter of the world bamboo area. Bamboo grows fast and can be repeatedly cutdown. Bamboo is an excellent paper material with its long fiber length.The utilization of bamboo is relatively little in pulp and paper industry dueto the lack of experience using bamboo in China. The characteristics of bamboofiber has not been fully predominated. This thesis mainly studied the filtration ofbleached kraft bamboo pulp. Studying the changes of bamboo fiber properties indifferent fiber lengths in comparison with the hardwood pulp and the wheatstraw pulp.This thesis obtain the following conclusions:(1)The bamboo pulp’sproperties of fiber length above30mesh,50mesh,100mesh and200mesh aresimilar. The four pulp are difference with the bamboo pure pulp. It is indicatedthat the bamboo fiber above200mesh is different from the bamboo fines.(2)Thebamboo pulp contains about28%of the fines which is very different from thelong-fiber components. The cell wall structure of long-fiber is complex, difficultto seperate more micro-fibers in the refining process, it swells difficult. Due tothe larger specific surface area, bamboo fines are fully swelling. Bamboo finesmakes the pulp filtrated difficulty, the beating degree rises faster after slightbeating action.(3) The properties of long fiber components of wheat straw pulpand the fines is similar. The properties of hardwood pulp’s long fiber and thefines is also similar.(4) Under the same refining revolutions, the beating degree’sorder is: wheat straw pulp> bamboo pulp> hardwood pulp; long fiber of wheatstraw> long fiber of hardwood> long fiber of bamboo. At the same beatingdegree, the water retention value’s order is: wheat straw pulp> bamboo pulp> hardwood pulp; long fiber of wheat straw> long fiber of hardwood> long fiber ofbamboo. Due to high content of fines, the cell wall of the wheat straw pulp andbamboo pulp is easy breaked and swell, beating degree and water retention valueis higher than that of hardwood pulp. Compared with the bamboo long fiber,wheat straw fiber and hardwood pulp fiber’s cell wall structure is simple andeasy breaked, the beating degree and water retention value is higher than bamboolong fiber in the refining operate.(5) Wheat straw fiber’s cell wall is thin andeasily ruptured when refining. It microfibrilling faster and strengthen the bindingforce of fibers. The tensile index and burst index is high because of the high fiberbinding force. Due to the short fiber length of wheat straw pulp, the tear indexand folding endurance is low. Due to the long average fiber length, the tear indexand folding endurance of bamboo pulp is high.(6) The fines without refining isadded into the refined bamboo long fiber pulp makes the beating degree and thewater retention value lower than the bamboo pulp. The tensile index, tear index,burst index and folding endurance are higher than the pure bamboo pulp at theearly stage, but are lower than the pure bamboo pulp at the late stage.