Study On The Dynamic Performance Of Size Film And Its Applications In Evaluation Of Modification Effect Of The Size Doped With Montmorillonite

It has always been highly concerned by the textile industry to improve the quality of warp sizing in the weaving technology. In recent years, the researches of new size and sizing additives, the optimization of sizing technology, especially the development and utilization of sizing agent doped by micro-nano material, have highly broaden new prospects for the improvement of the sizing quality. However, there're rarely the researches about the topic for a long time that, in the process of size developing and the optimization, how to control the quality in the process and to dependently brings forward the scientific prediction and accurate quality evaluation.This paper comprehensively summarized and analyzed the traditional sizing engineering quality system, and considered that although the traditional process quality control and evaluation methods are very effective in the actual production and research, these methods are still parts of the apparent, within the scope of experimental methods that deviate things from the essence, basically separated from the achievements of modern materials science. Especially, the static and single external factors modes are widely used in the test of the traditional mechanical performance which have caused that the testing results have significant difference from the actual working conditions of the size film.The paper believed that the sizing surface and film adhered to the fibers play the most important role in the waving efficiency. Sized yarn and its film are always under the motional changes with the running loom. These motional changes include not only a gradual change of their own structural performance, but also variety changes of external conditions. Regarding this, the size film should be tested and analyzed from dynamic perspective according to material science, and thus the linkages between the various factors are established. Accordingly, dynamic characteristics of the film are objectively and comprehensively characterized. This paper, rejecting the idea of traditional research from the macro to the macro-line, undertook much research work according to the performance of polymer materials and on the methodology for contemporary material science from the microscopic to the macro. Thus, new appropriate and scientific methods to test the performance of film were presented. These presented testing methods cover a wide range of sized yarns performance including properties of dynamic mechanical, wear resistance, fatigue resistance, the suitability of tensile modulus of the film and yarn, soften and re-sticky due to heat during the dynamic process, supplemented by affinity between the film and fiber,strength and extension of sizing yarn. The quality of the film and sizing are described objectively. However, the sizing engineering quality system is a system containing rich content which needs a long-term exploration and a process to gradually achieve perfect. This paper only focused on rational and scientific evaluation method of film to made some preliminary exploration and research.Based on the achievement, in nanotechnology, the new type of size mixture of PVA/phosphate starch doped by micro nano-montmorillonite powder is developed. Their various properties were studied adopting the new measuring methods presented by this paper. Meanwhile, the necessity of the scientific testing methods is validated through these researches and developments.The main researches included in this thesis are as following.Ⅰ. Several typical main sizes:modified starch, PVA and polyacrylate sizing were studied referring to the traditional test methods of the properties of film, grafting of the theory and the research findings in the field of modern materials science and engineering. It presented a relatively complete corresponding evaluation methods and test means of sizes performance from five parts, including dynamic tensile mechanical properties, dynamic fatigue resistance, dynamic wear-resistance, soften and re-sticky Properties during the dynamic process.1. The dynamic mechanical thermal analysis (DMA) is used to test dynamic tensile mechanical properties of the film and sizing yarn to test the relationship between the dynamic stress and strain and the dynamic changes of modulus. By means of two testing modes of the static and dynamic, the dynamic tensile mechanical properties of the film and sizing yarn have been tested and compared, and the analysis showed that test of dynamic tensile mechanical properties is important and realistic.The study found out that under the dynamic stress conditions, the value of dynamic modulus of the film is much larger than the elastic modulus of small deformation at the static tensile. Therefore, in actual production, we must consider the adaptation between the dynamic modulus of the film and sizing yarn.2. DMA is applied to test tensile creep-recovery and dynamic tensile stress of the film, both of which can evaluate the dynamic fatigue resistance. The test of tensile creep-recovery is a way that tests the strain recovery ability and creep properties of the film in repeated tensile loading and unloading. The traditional equation of recovery rate R of the film was improved, and the evaluation index of dynamic creep-recovery has been presented.The test of dynamic tensile stress is a way that test time- dynamic stress-strain curve under external alternating loads, frequency and test temperature of which are respectively determined by the speed of looms and the ambient temperature in the weaving workshop. The accumulation of the strain after exposure to a certain number of alternating external force is adopted to indicate the fatigue resistance.The film and its sizing yarn were tested using the methods of the tests of tensile creep-recovery and dynamic tensile stress. The test results show the fatigue-resistance of the film and sizing yarn have consistency, so testing film can be used to predicate the dynamic fatigue resistance of the corresponding yarn. Compared with the traditional test method, the tests of tensile creep-recovery and dynamic tensile stress are closer to the actual working situation.3. The wear tester of the sizing film under the condition of dynamic tensile was self developed. The Instrument can set the different parameters, such as film deformation amount, load for wear and deformation velocity, to simulate the actual working condition of the film in the looms. The wear number of film by friction is used to judge the wear resistance of the film when stretching. With the help of scanning electron microscope (SEM) and differential scanning calorimeter (DSC), the surface morphology and thermal properties of the film by alternately stretching were investigated. The testing results express that the film under stretching causes more serious wear than when the film is not stretched alternately, so testing the film under stretching alternately reflects the actual wear resistance of the film.4. Glass transition temperature (Tg) is used as an important parameter to present softening characteristic of the film due to heat. Dynamic mechanical analyzer(DMA) was applied to measure the value of glass transition temperature to assess and speculate the possibility of happening and extent of softening in real working condition. In the development of new size, the glass transition temperature would be controlled to maintaining the appropriate strength and softness of the film for ensuring normal weaving.5. under the high temperature and high humidity conditions in the weaving workshop, the size film as well as sizing yarn would have re-sticky phenomenon. In this paper, The contact angle on the size film dropped by deionized water has first been tested to judge the wettability of water on the sizing film. The smaller the contact angle can be, the better the wettability has, which make easier to absorb water and cause the phenomenon of re-sticky.Testing the thermal properties of the mixture of sizing and water with differential scanning calorimeter (DSC) can determine quantitatively the swelling temperature Tn,which presents that the size film will begin to appear re-sticky, and the enthalpy in the range from swelling temperature Tn to subsequentΔT temperature due to the swelling of size film, therefore, the swelling temperature Tn and the enthalpy will comprehensively describe structural changes of material and the extent of the phenomenon of re-sticky. So, the contact angle, swelling temperature and the enthalpy during theΔT temperature are listed as parameters comparing the re-sticky performance of various size film.The above five kinds of testing of dynamic properties of size film comparatively and factually describe the properties and functions of size film as well as sizing yarn. And they provide the reliable evaluation reference of process quality for the development of different kinds of sizing and the optimization of sizing engineering.Ⅱ. This paper developed specifically the size mixture, which appropriate to the polyester cotton yarn, of PVA-1799 and phosphate starch doped by micro nano-montmorillonite powder. The five methods for testing dynamic properties of the film were adopted, supplemented by testing of affinity between the film and fiber and strength and extension of sizing yarn, to control and optimize the size mixture and modification technology of doping micro nano-montmorillonite powder. Based on this, the modification effect are evaluatedFirst of all,low temperature plasma treatment has been used to deal with the surface modification for raw nano-montmorillonite powder. Then, the nano-montmorillonite disperse liquid were prepared by using the method of ultrasonic dispersion and their process conditions were determined. The average particle size in the disperse liquid by optimized process was 472 nm.PVA-1799 and phosphate starch were selected as the main sizing agent. As Zeta potential of both the size mixture of the PVA-1799/phosphate starch and the prepared disperse liquid of micro-nano-montmorillonite is negative or have the same phase-electricity, the two kinds of materials will not result in coagulation or agglomeration of the nano-powder when they are mixed. The structural analysis of infrared spectrum showed that micro-nano-montmorillonite is doped into sizing did not cause the change of chemical properties of the sizing agent. Through the XRD analysis of the film doped with nano-montmorillonite, it was indicated the phosphate starch and PVA-1799 act not only as the primary adhesive agent but also as a the assist intercalation agent for micro-nano-montmorillonite to further improve the dispersion extent of the powder.The film modified by micro nano-montmorillonite were studied through testing methods of the dynamic mechanical properties, dynamic fatigue performance, dynamic wear resistance, softening, re-sticky of the film, affinity between the film and polyester cotton fiber,strength and extension of sizing polyester cotton yarn. These studied results were used to optimize doping process and the proportion of the doping micro nano-montmorillonite. The testing and the comprehensive evaluation show that: doping with micro-nano-montmorillonite help to improve the dynamic properties of the film and sizing yarn of size mixture of PVA/phosphate starch. Of which, the proportion of micro nano-montmorillonite doped with 3% has the best effect.Based on the testing methods of the dynamic mechanical properties, dynamic wear resistance, dynamic fatigue performance, softening and re-sticky of the film, by combining the traditional affinity between the film and fiber, strength and extension of sizing yarn, this paper proposed a comparatively completed subsystem which belonged to sizing engineering quality system. This subsystem is more scientific and practical for size developing and it can be applied to the quality control in the process of sizing, the optimization of sizing technology and the evaluation of modification effect. At the same time, the study of this sub-system also provides new ideas and fundamental theories for sizing engineering quality system, which is being gradually improved.