Study On Refining, Structure And Physico-Chemical Properties Of Banana Fibers

China is one of the major banana planting countries among the world, and the output of banana in China is about five to six thousand tons. but only little of the byproduct, such as banana bast, banana leaf, banana stem, was produced into rope, sack, handbag and other textured products, most of them was discarded as garbage. This can not only cause the waste of resource, but also the environmental pollution.As a natural cellulosic fiber, the exploitation of banana fiber can not only replace the consumption of chemical fibers partly, but also satisfy people's psychological and physical demand for enjoying life and nature.Based on the chemical component quantitative analysis of banana bast, the paper compared it with other bast fibers, which guide/point out the right direction for degumming; the enzyme combined chemical degumming process was used to extract the banana fiber by referring to other bast fibers' degumming process and taking full advantage of enzyme and chemical degumming process. At last, the basic physical properties and the structure of banana fiber are studied. The conclusions are as follows:(1) Both the percentage of hemi-cellulose and lignin in banana bast are high, which is 23.52～25.04% and 13～14% respectively. The high percentage of lignin must cause difficulty in degumming the banana bast. So how to remove lignin is the key point of the study.(2) Among the four pretreatment methods chosen, that is immerse, pickling, ultrasonic and immerse combined ultrasonic, the effect and efficiency of pickling on removing pectin is superior to other pretreatments. The parameter of the process are: concentrationof H₂SO₄ 2g/L, bath ratio1:20, bath temperature 50℃, time 2h, normal pressure.(3) The primary chemical degumming process of banana fiber was taken as the follow route:Sample preparation→pickling→washing→alkali liquor boiling→washing stamping→acid washing→washing→dehydration→oiling→dehydration→loosing→drying→banana fiber.The parameters of each process are:Pickling: concentration of H₂SO₄ 2g/L, bath rationl: 20, water bath heating at 50℃, time 2h, normal pressure;Alkali-H₂O₂ one-bath boiling: concentration of NaOH 8g/L, H₂O₂ 6g/L, Na₂SiO₃ 3%, boiling under normal pressure, bath ratio 1:20, time3h, heat-up time 35～40min;Souring: concentration of H₂O₄ 2g/L, bath ration1:20, time 2～3min, normal tempreture and pressure;Oil finish: BSK1.5%, 10min, normal tempreture.The residual pectin and lignin of the degummed fibers got are 6.94% and 3.93% respectively.(4) Based on the chemical degumming process, the enzyme combined chemical degumming process was taken as follow:Sample preparation→pickling→washing→enzyme treatment→hot water washing→alkali liquor boiling→washing stamping→acid washing→washing→dehydration→oiling→dehydration→loosing→drying→banana fiber.The parameters of each process are:Enzyme treatment: owf10%; time8 h; pH 8, 55℃, bath ratio1:20; other parameters are the same as that used in the chemical degumming process.(5) Under the best process condition, banana fiber has a primary ability in spinning, with its strength 88.63cN, extension3.11%, fineness 3.13tex.(6) Based on the measurement of banana fiber's shape structure, the surface of banana fiber is silky and has convolutions, with cross marking of some fibers. It shows the banana fiber has the shape characteristic of cotton and bast fibers.(7) Based on the infrared spectral and X-ray diffraction analysis of banana bast, it has the characteristic group of cellulosic fiber, the crystallization degree and degree of orientation are 61.55% and 0.8690.Based on study of the dissertation, the author believes the banana fiber is of great exploitation value as a newly zoology fiber.