Study On The Surface Adsorption Characteristics Of Natural Cellulose Fiber To Oil

The natural fibers were used widely in the field of oil adsorption for the past few years due to some advantages such as excellent oil absorption capacity, rich resources, cheap, easily obtainable, renewable, biodegradable and so on. The paper was focused on the four kinds of natural cellulose fiber such as cotton fiber, kapok fiber, cattail fiber and flax to make clear the adsorption characteristics, the effect factors, and explore the different methods to test the adsorption of the four kinds of fiber.The main work was including the four fields as following:(1) Contact angle test of the fibers to the different kinds of liquidThe static contact angle and dynamic spread process of cotton fiber, kapok fiber, cattail fiber and flax with different kinds of liquids such as water, engine oil, used oil and vegetable oil were investigated using Optical Contact Angle Measuring Device (OCA15EC). It was found that, cotton fiber, kapok fiber, cattail fiber are the excellent oleophylic and hydrophobic fibers with the contact angle of fiber to water are more than 130.00°, but to various kinds of oil are less than 60°, flax is a hydrophilic and oleophylic fiber with the contact angle of flax to water and other three kinds of oil are less than 50.00°. In addition, the contact angle of fibers to water is the constant with the time flies except flax. All the oil liquids on the fibers have quick spreading rates, and the spread curves were similar and can be well fitted with exponential functions.(2) Surface free energy calculation of the kinds of fibersAccording to the theory of geometric mean contact angle method, we calculated the surface free energy as well as their polar and non-polar components of four natural cellulose fibers using the software of OCA15EC Measuring Device. It was showed that the surface free energy of four kinds of natural cellulose fibers were about 50.00 mN/m, and the polar component of cotton, kapok and cattail fibers was more larger than the non-polar component except flax, the content of polar component of flax was slightly less than non-polar component. (3) Influence factors of the fibers'adsorptionThe JSM-5600LV SEM, Optical Microscopy(Labomed), X-ray Diffraction, Soxhlet Extraction were used to observe and test the morphological structure, crystallinity, wax content of cotton fiber, kapok fiber, cattail fiber and flax. The Digital Spinning Viscometer(SNB-2) and Surface Tension/Dynamic Contact Angle Tester(DCAT11) were used to test characteristics of the liquids such as viscosity and surface tension.The analysis showed that, the structures of the natural twist and lumen of cotton, the large lumen of kapok fiber, the bamboo-like interior profile along the longitudinal section of cattail fiber, and the longitudinal bamboo joints and the lumen of flax fiber, are the important factors to determine the excellent adsorption to the different liquids. The crystallinity of cotton, kapok, cattail fiber and flax were 68.00%,32.70%,45.41% and 66.12% respectively. The smaller crystallinity, the larger amorphous area, especially for kapok and cattail fiber, are more favorable of the liquids into the fibers. The wax content of cotton fiber, kapok fiber, cattail fiber and flax fiber were 0.60%,0.80%,10.64% and 2.26% respectively, the larger amount of wax content, the more oleophylic and hydrophobic properties of fibers. The low surface free energy of the fibers was the important factor to determine the adsorption properties of fibers to different kinds of liquids. Considering the different liquids, the small surface tension and viscosity of the liquids determined the speedy spread of the liquids on the fiber surfaces.(4) Comparison and analysis of the test methods of contact angle of the fibersBased on the features of OCA15EC measuring device and DCAT11 tester, the contact angle was tested between four kinds of fiber and different liquids such as water, engine oil, used oil and vegetable oil by using plate-like method, sessile drop method and dynamic contact angle measurement. The results showed that three methods could well test the contact angle of the four kinds of fiber to different oil liquids. By contrast, plate-like method was appropriate for various samples, but sample preparation was strick in need of the fibers evenly on the glasses. Sessile drop method was generally applicable to the pro-liquid fibers, but the dimension of single fiber was fine, so it was difficult to operate. Dynamic contact angle measurement was more stable, but the method need to know the cross-sectional area and perimeter of fibers, and also this method was appropriate for the fibers that have greater hardness and regular cross-section. The capillary constant of kapok fiber was investigated by using Washburn method. It was found that the coefficient of variation of capillary constant was great, and so the Washburn method to test contact angle between kapok fiber and liquid need to be explored in the future.