Grafting Copolymerization Of Xylan And Its Improvement On Paper Properties

In our country,straw pulp and secondary recycled pulp are the main pulps,but there are some problems such as short fibers and poor papermaking performance,which restrict the development of papermaking industry.Paper additives are widely used in the paper industry because they can improve the dispersion of pulp fibers and the bonding between pulp fibers,thereby improving the strength and other properties of paper.However,there are many problems in our country papermaking additives,such as simplification,old products,poor performance.Natural polymer papermaking additives are widely used because of their low price,degradability and renewability.Hemicellulose as the abundance resource is a natural polymer.Xylan is one of the most important components of hemicellulose,its sugar unit chain contains many active hydroxyl groups which can be used as sites for chemical modification,thus giving xylan various chemical properties.In this paper,in order to endowing xylan with papermaking addivtive properties,three kinds of xylan polymers with different structures and properties were prepared by graft copolymerization of acrylamide,guanidine polymer and poly(perfluorooctylethyl methacrylate)onto xylan.They were used as paper additives in papermaking to explore their effects on paper properties.The main researches are described as follows:1.Xylan-grafted polyacrylamide(Xylan-g-PAM)was prepared by graft copolymerization with xylan as a raw material using acrylamide as monoers.Xylan-g-PAM with different grafting rates was prepared by controlling the reaction conditions,the influence of xylan-g-PAM on waste paper pulp properties and the influence of xylan-g-PAM combined with fine fibers and cationic fine fibers on waste paper pulp properties were studied.The results showed that when initiator concentration was 0.015 mol/L,monomer concentration was 0.40 mol/L,temperature was 60°C and time was 4 hours,the grafting rate and grafting efficiency of xylan-g-PAM reached 14.7%and 61%,respectively.These polymers could obviously improve the properties of waste paper pulp,the adding amount of 1.0 wt%xylan-g-PAM was to improve paper property,compared with the blank,the tensile index,tear index and burst index of paper increased by 35.54%,49.17%and 46.67%,respectively.Xylan-g-PAM and cationic fine fibers were added together could significantly improve some properties of paper pulp,especially the tensile index,which is 49.09%higher than that of the blank sample.These results indicated that xylan-g-PAM could be used as paper strength agent in paper strength improvement.2.Considerating the antimicrobial activity of guanidine polymer,cationic xylan-grafted polyhexamethylene guanidine hydrochloride(PHGH)(CX-g-PHGH)was prepared by graft copolymerization with cationic xylan with good water solubility as a raw material.The optimum preparation conditions were investigated by orthogonal experiment.The influence of CX-g-PHGH with different grafting rates on paper mechanical properties and bacteriostasis were investigated.The results showed that when initiator concentration was 4 mmol/L,monomer concentration was 0.039 mol/L,temperature was 60°C and time was 4 hours,the grafting rate and grafting efficiency of CX-g-PHGH reached 18.45%and 58.45%,respectively.These polymers could obviously improve the mechanical and antimicrobial properties of waste paper pulp.Compared with the blank,tensile index,tear index,burst index and folding strength of paper were increased by 20.07%,25.31%,30.20%and 77.78%,respectively.In the antimicrobial test of xylan and CX-g-PHGH paper,CX-g-PHGH had a good antimicrobial effect on paper,and had a good antimicrobial effect on Escherichia coli.These results indicated that the addition of CX-g-PHGH to the pulp could give the paper better strength and antimicrobial properties.3.Cationic xylan grafted poly(perfluorooctylethyl methacrylate)(CX-g-PFOEMA)with hydrophobic was prepared by atom transfer radical polymerization(ATRP)with xylan as a raw material.The influence of reaction conditions on the grafting ratio and grafing effiency of CX-g-PFOEMA and the influence of these polymers on the the mechanical and hydrophobic properties of filter paper by coating were discussed.The results showed that when catalyst concentration was 7 mmol/L,monomer concentration was 0.018 mol/L,temperature was50°C and time was 4 hours,the maximal grafting rate of CX-g-PHGH was 30.39%.These products could obviously improve the mechanical properties and hydrophobic properties of filter paper.When the coating amount was 10 g/m~2 and the grafting rate was 30.39%,the mechanical properties of filter paper were improved to the greatest extent.Compared with the original paper,the paper tensile index was increased by 24%,tear index was increased by18.01%,burst index was increased by 30%,folding resistance was increased by 300%.Paper coated with CX-g-PFOEMA could be used for hydrophobic test,which could effectively improve the hydrophobicity of paper.When the coating amount was 12 g/m~2 and the grafting rate was 30.39%,the hydrophobic effect of paper was the best(Contact angle>150 ~o).These products could be used as a surface sizing agent to improve the strength and hydrophobicity of paper.Based on the active hydroxyl of xylan and the functional properties of acrylamide,guanidine salt polymer and 2-(perfluorooctyl)ethyl methacrylate,a series of xylan grafted products with different structures and functions were designed and prepared by the grafting coolymeriztion,which were used as paper strength agents,antimicrobial agents and hydrophobic agents in paper making,food packaging,waterproof/mildew-proof paper and other fields.