| Nowadays, polyvinyl alcohol (PVA), acrylic copolymers and starch are the three main sizes in the sizing market, and make great contribution to weaving. PVA can form strong film and has good performance on sizing in spite of some defections as a size. It is one of the major sizes for polyester/cotton yarns. But PVA has some problems in environmental protection. It will cause ecological contamination because PVA is not easy to be biodegradated, which will lead to accumulation in nature after long period of time. And now the whole world is increasing the awareness of environmental protection and building a pattern of sustainable economy. Under this condition, PVA was abandoned in many countries, especially in developed countries. Our nation also advocate to use PVA in small quantity or not to use it. So the application of three main kinds of sizes is changing, the usage of starch and acrylic size is growing. At present, the studies focus on the denaturalization of starch and development of new acrylic size. Potential size substitution of PVA is acrylic size. Earlier acrylic size has the merits of adhesion and flexibility and demerits of hygroscope, tackiness and too soft film which limit size using in large quantity. In recent years, great attention has been paid to a method in which some inorganic nano-material is added into current sizing agents to improve sizing properties of the sizes. So, in this paper, a size named acrylic copolymer/Na-MMT nanocomposite size was mainly studied, aiming at solving above problems and making new acrylic size to have properties higher than or as same as PVA. Nanocomposites are a new class of composites that are particle-filled polymers for which at least one dimension of the dispersed particles is in the nanometer range. And the physical and chemical properties of polymer nanocomposites can be enhanced dramatically by incorporating nano-microparticles because of their characteristics such as surface effect,quantum-dimension effect,macro-quantum tunneling effect and so on. Therefore, the polymer/layered silicates nanocomposites have developed world wide both in academic and in industry.In view that there is no report published in this aspect about polymer/layered silicate nanocomposites used for warp sizing, the purpose of the thesis is to develop soluble polymer/montmorillonite nanocomposites for warp sizing. In the study, the pristine Na~+-MMT was chosen as the predecessors of nano-particles, two soluble polymer/montmorillonite (MMT) nanocomposites were prepared by in-situ intercalative polymerization of acrylic acid (AA), acrylamide (AM) and methyl acrylate (MA) in water solution, and by intercalation of poly(vinyl alcohol) (PVA) from solution, respectively.For the acrylic copolymer/Na-MMT nanocomposite size, XRD, TEM, FT-IR spectra were used to characterize the interlayer space and configuration of MMT in the polymer matrix, and the surface chemical structure of the polymer nanocopmposite, respectively. The glass transition temperature, T_g, was determined by DSC, and application properties were tested for the nanocomposite size. The results indicated that a exfoliated structure can be obtained corresponding to Na~+ -MMT content of below 5(wt)%, As a result the nanometer additive can give the size better abrasion resistance, better adherence to fiber, together with increasing T~g of the size and viscosity of the solution, and with reducing moisture absorption of size film.For PVA/Na~+-MMT nanocomposite size, the interlayer space of the nanocomposite was characterized by means of XRD. The results revealed that the degree of intercalation varies with amount of Na~+-MMT in the hybrid: An exfoliated structure corresponds to Na~+-MMT content of below 5(wt) %, or else it become intercalated structure. Compared with the acrylic copolymer/N~a~+-MMT nanocomposite size, the PVA/Na~+-MMT nanocomposite size can enhance the adhesion to the T/C blended yarn but have little influence on the strength and elongation. |
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