Study On The Preparation Of Amphoteric-Polyacrylamide-Based Papermaking Retention And Drainage Aid Via Inverse-Microemulsion Polymerization

Amphoteric-polyacrylamide-basedchemicals have been extensively applied in manyindustries including papermaking, oil and environmental protection. With both negative andpositive groups on their polymer chains and with striking "anti-polyelectrolyte" characteristics,these polymers are generally considered to be suitable for use in a wide range of pH conditionsin papermaking. However, there are many disadvantages associated with the commonly appliedpreparation procedures, for example, water-solution-polymerization-based polymer productsusually have strong tendency of crosslinking, and the molecular weight distribution ofinverse-emulsion-polymerization-based products are always too wide to be suitable for use inspecific applications. In order to overcome these disadvantages, development of novelamphoteric-polyacrylamide-based retention and drainage aids was explored.The preparation of inverse-microemulsion polymerization system of DADMAC/AM/AAwas studied by conductivity measurements and visual observations, the results show that, theoptimum oil phase, emulfying system, monomers Consistency and weight ratio of monomersare hexamethylene, SpanS0-Tween60, 55% and 1.5:7:1.5 respectively, and the minimumdosage of emulsifiers and maximum dosage of monomers are 17.65% and 33.33%. The resultsalso show that, the weight ratio of oil phase to emulsifiers should be well kept in the range of3:7～7:3. Effect of monomers cgnsistency, weight ratio of monomers, HLB and electrolytes onstability of inverse-microemulsion polymerization system were subsequently studied, and theresults show that, stable inverse-microemulsion polymerization system can be obtained whenthe monomers consistency and HLB are in the range of 40%～65% and 5.36～8.54 respectively,increased dosage of acrylamide and incorporation of NaAc into the system can further enhancethe stability.Effect of EDTA dosage, N₂ charging, stirring speed, dosage of emulsifiers, dosage ofinitiating agents, monomers consistency, reaction temperature and reaction time on molecularweight of amphoteric polymer, reaction yield, emulsion stability and retention and drainage aidproperties were intensively investigated. Orthogonal analytical method was then applied todiscuss the influence of reaction temperature, initiators dosage, reaction time and monomersconsistency on molecular weight, reaction yield, emulsion stability and retention and drainage aidproperties of the polymer products. The results show that, the optimum conditions for thepreparation of the polymer product are: EDTA dosage of 0.5%, N₂ charging time of 20min, stirringtime of 300r/min, emulsifier dosage of 18%, initiators dosage of 0.4%, monomers consistencyof 54%, reaction temperature of 24℃and reaction time of 3h. The results also show that, theoptimum pH is 7.12. The synthetic product of amphoteric polymer was then characterized by IR and UV.The ternary phase diagram of emulsifiers, monomers solution and hexamethylene wasobtained by conductivity analysis and visual observations, and the scope of study on kineticswas selected. According to the results of kinetics, the apparent activation energy of thepolymer reaction is 9.84kJ/mol. Effect of reaction temperature, monomers consistency,emulsifiers dosage and initiators dosage on reaction rate and molecular weight was thenstudied, and the equations were obtained (Rp^∝[M]^1.05[E]^0.21[I]^0.35, M_v^∝[M]^1.18[E]^-1.16[I]^0.24).SEM was then applied for the characterization of the morphology of emulsion particles and itsvariations during the polymerization reaction.The novel amphoteric polymer product was then applied as retention and drainage aids inmaking handsheets using straw pulp. The results show that, the optimum conditions are:molecular weight of 300 0000, cationic monomer content of 25%, furnish pH of 8.0. Thesynergic effect of the polymer product with cofactors including CPAM, CS, CHPG, PAE andPEO was then discussed, PDAA, CPAM, CS and CHPG are shown to be quite effective inperformance enhancement of retention and drainage, certain effect can be achieved with PAE,and the effect of PEO is not obvious.The polymer product developed in this work has many advantages, and it can besuccessfully applied as retention and drainage aid in papermaking. The application of theproduct can lower the manufacturing cost and enhance the competitiveness of the relevantpapermaking mills.