The Research Of Modified Mechanical Pulp To Improve Paper’s Strength And Its Changing-mechanism

Chemical mechanical pulp has been applied wildly by many papermakers since been produced, Its wildly used due to the characteristics of chemi-mechanical pulp. High yield and low cost advantages are the main reason why chemi-mechanical pulp is wildly used. Chemi-mechanical pulp also has many other advantages such as low pollution and high bulk. But compared with the chemical pulp, chemi-mechanical pulp has its own Shortcoming, for example, the strength properties of paper made by the chemi-mechanical are lower. Overall, high bulk of the chemi-mechanical should be retained and its strength properties should be improved by modifying the fiber.In this paper, the strength properties of paper were improved firstly by beating the pulp, then the beated pulp was hydroxyethyled with the ethylene oxide (Eto) in chosen beating degree. The beated pulp was mercerized with higher concentration of NaOH solution, then the pulp was treated by Eto solution. The hydroxyethyl treatment was occur in different amount of ethylene oxide, alkali concentration, temperature, processing time. The cellulose hydroxyethylation was cross linked treatment, the polar hydroxyl groups of the cellulose macromolecules were increased in this treatment. These hydroxyl improved the affinity of the fiber with water, which improved the strength properties of paper. In addition the microscopic changes of fiber were explored with the help of microscope, infrared spectrum analysis (FT-IR), scanning electron microscope (SEM). Considering comprehensive factors the better technological conditions are as follow:Eto usage:14%, temperature:room temperature (25℃), alkali concentration:2.5%, the processing time:2 h.In this paper, the hydroxyethyl fiber was treated with LMS in order to improve the strength properties of paper. Laccase can react with the lignin, there was a lot of lignin in chemi-mechanical pulp, so phenol oxygen free radical of lignin was increased with the action of laccase. Therefore, mechanical pulp and mediator radical are started up a crosslinking reaction, In the cross-linking reaction, Polyphenols act as bridging agent role,The combined effect of these reactions made mechanical pulp paper’s strength improved.The mechanical pulp treated and untreated are use FQA, SEM to analysis fiber morphology, The results show that the treatment effect of the fiber is obvious, However, the reaction mainly occurs in lignin, cellulose and hemicellulose were little changed. Considering comprehensive factors, the better technological conditions are as follow:paint enzyme dosage:2 IU/g, copula:0.5%, slurry concentration:4%, time:1 h, the temperature:50 ℃, pH:5.0...