A New Method To Produce A Flax Fiber Structure

With the environment problem worse and worse, the concept of environmental protection of people and governments is more and more strong. With this background, various research groups have worked on examined natural fibers, because of its biodegradable and recyclable. At this situation, using the waste flax fiber or the low quality flax fiber to do the research for researching the potential application is very significant. This thesis is focused on the process of making a flax/water felt. The theory about this felt is similar to the papermaking. Since the hydrogen bond between the cellulose molecule of flax fiber and the water molecule and the cellulose molecule of flax fiber bonding with each other, it makes that producing the flax/water felt is possible. This felt is100%nature and can degrade in the natural environment.This thesis is focused on the possibility to make the flax/water felt and also on optimizing the parameters of the felt fabricating process to achieve good properties for the integrated felt. From the results of the basis weight, thickness, tensile and flexural tests for flax/water felt, the optimized fabrication water concentration, pressure and temperature were addressed. The main content of this thesis is divided to these parts:The chapter one is literature review. The background of this thesis, the objective and the meaning of this research are described it also includes the research status of the relative area.The chapter two contains the materials of this research, the requirement for producing, the producing methods and the testing methods. The process of the producing methods is divided to3parts, including flax preparation, felt preparation and felt production. For the flax preparation, use the Retsch ZM1000centrifugal grinder to grind the flax fiber for two hours. The rotational velocity is40rpm. The result of grinding makes the flax fiber like "powder". For the felt preparation, Water was added to flax after putting the fiber into the stirred vessel and the system was hand-mixed for15minutes. The fibers eventually became "sticky". For the felt production, each sample was sandwiched between aluminum foil and pressed on Wabash MPI/model G80H-18-BCPX.The parameters of the research are as followed. The range of water concentration (wt%) is from60%to75%.The range of pressing force is from8ton to14ton.The range of pressing temperature is from150℃to180℃.The pressing time is5minutes.In the chapter three, after producing samples, they were evaluated for thickness, basis weight, and tensile and flexural properties. The aim of the entire characterization was to determine the optimized fabrication in terms of water concentration, pressure, and temperature. The results and the explanation of these results are as followed.1. The thickness test is based on ASTM D6988standard. The best thickness of the felt should be in65%water concentration (wt%),8ton and165℃.2. The basis weight test is based on ASTM D3776standard. The best basis weight of the felt should be in65%water concentration (wt%),12ton and165℃. The accuracy of the thickness and basis weight determinations may be not good because the preparation of materials and production of the felt was done manually. Thus, it was difficult to maintain uniformity, so the result of thickness can only be regarded as reference data.3. The tensile test is based on ASTM D638standard. The best tensile strength of the felt should be in65%water concentration (wt%),12ton and165℃.The main reason is that when water weight content increases, flax swell well and will help the distance among flaxes decrease, then the hydrogen bond should easy form, so the tensile strength increase. When water weight content increases too much, the felt does not have enough flax fiber to load the force in unit area, so tensile strength decreases. About the pressing forces, as the pressing force increasing, the distance among flaxes decreases. It is helpful for forming hydrogen bond, so the tensile strength increases. When the pressing force is too big, it would damage to the flax fiber, so the tensile strength decreases. For the temperature, when the temperature is around150℃, the speed of evaporating water is not so fast, and then the bond in the felt could not be formed quickly, so it would Influence the tensile strength of this felt. But when the temperature is around180℃, part of the flax starts decomposed and the tensile strength decreases. Tensile strain of all the samples is not good, because the amorphous regions between the cellulose microfibrils are already oriented, and therefore not capable to deform plastically.4. The flexural test is based on ASTM D790standard. The best tensile strength of the felt should be in60%water concentration (wt%),12ton and165℃.The reason is that when increasing the water concentration (wt%), samples made with higher percentages of water had greater surface irregularities or defects and it affects the flexural strength more than the other mechanical properties of the material. The reason of the different pressing forces and different temperature are similar to the tensile strength.In addition, in the chapter three, the author uses the similar products to compare with the felt and describe the problem during the making the felt and testing the felt. Also the potential applications are mentioned, the potential application may be in interlinings for automobile and building construction, wall coverings and disposable industrial products. This felt just the first step of the research result, not the final product; some potential applications will be listed. Some applications of this list may be not suitable with the recent felt properties, but give a long goal for next step research to achieve.The chapter four includes conclusions and further work. All the conclusion and further work are mentioned in this chapter.