Synthesis And Modification Of AM-St Copolymer And Application In Papermaking

In order to improve the intensity of paper made from recycled pulps, synthesis and modification of AM-ST copolymer and its application in recycled pulp papermaking were studied.In the 2nd chapter, the conditions for obtaining the PAM-ST emulsion which has high solid content, low viscidity and ratio of the remnant monomer were found out that the early concentration of the reactant (C₀) was 30%, the quality percent of the acrylamide (c(Am)) was 50%, the initiator was K₂S₂O₅-NaHSO₃. The conclusion showed out that the grade of initiator for the rate in early polymerization was 1 and the activation energy was 51.96 KJ/mol, augmenting the amount of reducing agent (N_aHSO₃) would induce increasing of the total conversion ratio when the mol-ratio of reducing agent and oxidizer was less than 2. In the 3rd chapter, the hydrolysis was studied; it can provide negative charges to the surface of the latexes. The influence of dosage of alkali on the degree of hydrolysis, the particle diameter and the amount of surface charge were investigated, and the results showed out that the grade of NaOH for the rate of hydrolysis was 0.45. The theory equation between dosage of alkali and the amount of surface charge was modified by introducing a parameter- availability of alkali, which tallied with the experimental date very well. In the chapter 4, the application effect of the soap-free latexes in recycled pulp papermaking as dry strength additives was studied.The hydrolyzed product x-0.1, x-0.2, x-0.3, in which the mass-ratio of acrylamide was 50%, got the excellent effect for the paper made from the recycled pulps of waste corrugated paperboard box;and the latexes in which the mol-ratio of acrylamide-styrene-the 3rd component (butylacrylate,BA; methylmethacrylate;MMA ) was 7:2:1 and the degree of hydrolysis was 35% have excellent strength effect for the dry tensile strength index of the paper made from bleached pulps, the amplitude can be more than 30%.