Effect Of PVA Fiber On The Structure And Properties Of Sheet

According to producing practice, improving paper properties was one of the most effective ways to realize sustainable development for paper companies, and it was the main technique method to high performance of paper by using specialty fiber in effectively. In this study, Dynamic Sheet Former (DSF) was used to simulate the process of layered papermaking on multilayer inclined wire formers, and the effects of distribution of soluble PVA fiber on paper strength properties were analyzed; meanwhile, the effects of combination between PVA fiber and pulp fiber on the MD and CD strength properties of paper were discussed during the forming and drying process. The results showed that the structure of "sandwich" could enhance the strength of sheet and avoid the adhesion between the cylinder and sheet.The optimal efficiency can be acquired by optimizing the Parameters of DSF, and the addition of PVA70 fiber has a posotive effect(the break length increased by 17%) on strength properties of Northern Bleached Softwood Kraft (NBKP) under the following conditions:0.8% to 1.0% dosage of PVA70, the pneumatic control value 2 bar to 3 bar, the drying temperature 95℃.Different length of high strength and high modulus polyvinyl alcohol (HSHMPVA) fiber and pulp fiber were used to verify the effect of fiber length on the sheet strength properties, and the HSHMPVA were modified to enhance the bonding strength between the adjacent fibers. The chitosan coating method was adopted effectively by comparing the effects of different methods on the modification of HSHMPVA fiber. In addition, the effects of fiber orientation on paper strength were studied by using dynamic sheet formation and tensile stiffness orientation tester. The results showed that the water soluble PVA fiber could improve the bonding strength between HSHMPVA fiber and pulp fiber and alleviate the angle of fiber on MD in the dynamic sheet forming process, and then improve the paper strength.Finally, the mechanism of PVA enhancement of sheet was studied. The reinforcing effects of PVA on fiber bonding were discussed by the comparison of adding methods of PVA, such as the vacuum filtration, centrifugation impregnated and general impregnated, meanwhile, the existence of "effective adsorption" was proved by SEM and CLSM image; Then, the hybrid model and semi-empirical model of PVA content on breaking length were modified in the base of experimental data, and the effect of PVA on high-strength paper properties were analyzed by the modified formulas, and the dissolution and impregnation of PVA were showed to be the main way to improve the interfiber bonding.