Study On Modification And Application Of Phosphorus Gypsum Whiskers

As a kind of reinforcing material, Phosphorus gypsum whisker not only can save the dosage of pulping, but also can reduce the emissions of industrial waste in paper-making industry. It has broad prospects because it can protect the forest resource and use waste gypsum at the same time.In this paper, the physical and chemical properties of phosphorus gypsum whiskers were comprehensively studied by a variety of analytical instruments, and TSAX and YZSG were used respectively to inhibit the dissolving of phosphorus gypsum whiskers based on its structural properties and characteristics. Then analyze the change of the solubility and conductivity of whiskers before and after modification, also inspect the influence of loading quantity, pulp beating degree and retention agent on the filling effect of Phosphorus gypsum whisker and modified whisker. The experimental results show that phosphorus gypsum whisker is a mineral fiber with hydroxyl groups and-SO4 on the surface and its whiteness is high, but its water-solubility is still high.In the modified experiments, the solubility and conductivity of phosphorus gypsum whiskers can be reduced by TSAX and YZSG because they can coat successfully on the surface of whiskers and formed an effective package membrance. The best conditions of modification by YZSG were reaction temperature 60℃, reaction time 30 minutes and the dosage of modifier 2.00%. The solubility of whisker can reduce from 0.33g to 0.11g after modification by YZSG. The best conditions of modification by TSAX were the concentration of modifier is 0.25 mol·L-1, reaction time 3 hours and reaction temperature 40℃. Even the secondary modification effect is better than the first modification effect under the best modification conditions. The solubility of whisker can reduce from 0.21g to 0.11g and the conductivity of whisker can reduce from 1.73ms·cm-1 to 1.32ms·cm-1 after modification by TSAX.In the papermaking experiments, the results showed that the paper, which filled with the phosphorus gypsum whiskers which were modified with YZSG and TSZX, can obtain an equal whiteness and physical strength (such as burst index, tear index and tensile index). However, the retention of whiskers was improved to a certain extent, can be improved from thirteen percent and twenty percent to twenty percent and fifty percent, respectively.The suitable dosage of whisker which was modified by YZSG was in the range of twenty-five percent to thirty percent and the suitable beating degree of softwood pulp was in the range of 400SR to 500SR. And the manufacture cost of paper can be reduced well at the basis of maintaining a high retention of whisker and paper strength.The retention agent of PAM1 and the binary retention system of PAM1-CS have better effect on the retention of calcium sulfate whisker which was provided by Hubei. The results showed that the retention of whisker can increase from 51.5% to 57.8 and 65.5%, respectively.