The Observation Of The Mechanical Degumming Method Of HemP

The hemp fiber is the most prospective cellulosic fibre in the future. It has many natural healthcare functions such as good bacterial repellency & inhibition, good absorption-air permeability, shielding radiation, it is emollient, frash and comfortable. What's more, the hemp has the ecology-safe-productivity and end-product-recycling, it is the real "green product". So many experts believe that hemp is the ideal textile fibre.However ,because of the developed hemp products faulty preliminary working,the advantage of the hemp has not been brought into full play,so the quality of the hemp products is low.Degumming is proved to be an important position in the preliminary working. The typical quality of the hemp fibre makes the degumming process very difficult. To make a comprehensive survey, there are three methods for the hemp dugumming: natural fermentation, chemical dugumming and biological degumming. The natural fermentation has many disadvantages such as long processing time, much dependence on the circumstance and having not much quality assurance; chemical degumming often use methods of ramie degumming, namely the processes of degumming and bleaching in two steps or more, which have the disadvantages of long process and time, high-cost and consumption; though the biological degumming has little energy consumption, the degumming is incomplete, it need secondary chemical degumming.To resolve the problems as mentioned above, we choose the mechanical method to remove the gums in the hemp. Mechanical method uses a roller to roll the hemp which has been arranged by some way. The method can save time and protect the environment because it can't produce the waste water and waste air ,moreover, it can improve the utilization ratio of the hemp fiber and get the high quality textile fiber.The main content of this paper is as following : 1. tudy the main chemical component of the raw hemp and definite the probably existingrelationship among the cellulose and hemicellulose and lignin.2. Analyze the arrangement of the fiber and the gum in the raw hemp and regard the hemp flat as the unidirectional fiber reinforced composite material.3. According to the hemp fiber is tough material and gum is fragile material, analyze thereason why the gums is crashed when the hemp is rolled by the roll.4. Establish right mechanical model and find the main parameters which can influencedthe degumming result. Under the specified conditions in this paper, we abtained the following conclusions:1. Hemp fibers possess a high degree of tenacity, strength and breaking extention, while the surrounded pectin, ash and lips are brittle material. So that it can be regarded ascomposite material --the parallelly arranged hemp fiber is reinforcing materialand the brittle gums are matrix.2. As for the mechanism of gums crashing, it is concluded that during the process ofrolling, the cracks first are generated in the gums and then expand to the fiber/fums interface. Owing to the different mechanical properties of fibers and gums, they can decoherence in the interface leading to the crashing of gums, then gums separate out from the fibers.3. Analysis about the mechanical model of gums crashing shows that the changes of modulus of elasticity is an indicative of the state of hemp degumming. The state can be determined by measuring the value of modulus. If the value is high, which means only minor effects on gums. With the increase of external-load, the modulus of elasticity become smaller signifying the more removal of gums. So the external-load can be added until the modulus tends to be a constant with the premise of the value below the hemp's breaking stress to protect the hemp undestroyed.