Lignin graft copolymerization of acrylic monomer -1
Lignin monomer vinyl radical graft copolymerization , the most studied is the reaction of lignin and acrylamide because these monomers acrylamide maximum activity , the use of a cerium salt initiator , H2O22Fe (Ⅱ ) , potassium permanganate , persulfate , and γ2 rays.
0.001mol/LNaOH dissolved lignin solution , adjusted with 5% H2SO4 to pH 8 , concentration of 1g / L, with ceric ammonium nitrate as an initiator , and copolymerized acrylamide . They found that the grafting reaction product , relative molecular mass less than 50,000 parts significantly reduced, more than 100,000 parts increased significantly , almost no less than 5000 parts of the graft reaction can only generate short-chain , the relative molecular mass of each segment molecules also varies considerably ; from scanning electron microscopy (SEM) shows the surface of the grafted products mesh structure exist, but the lignin ratio , has been basically no larger mesh , and the mesh is vague .
Of lignin sulfonate and acrylamide or acrylic acid graft copolymerization reaction conditions : lignin sulfonate
0.5g (7.35 × 10-4mol / L), the monomer acrylic acid 2.5mL (0.72mol / L) or acrylamide, 2.5g (0.70mol / L), ferrous chloride 18.5mg (2.95 × 10-3mol / L) , hydrogen peroxide 20mg (1.18 × 10-2mol / L), the reaction medium 50mL, reaction temperature of lignin sulfonate – acrylic system is 30 ℃, the lignin sulfonate – acrylamide system is 50 ℃, reaction time is 2h. Extracted with ethanol homopolymer of acrylic acid , and then extracted with methanol and the copolymer , the lignin sulfonate – acrylamide reaction , unreacted lignosulfonate with dimethyl formamide extraction .
MozeA , also studied the lignin and acrylamide , acrylic acid graft copolymer , the choice of CaCl2-H2O2 as initiator system, and effects of reaction temperature , the amount of monomer and lignin monomer ratio. H2O2-Fe (Ⅱ) is the most commonly used initiator in the graft copolymerization , ferrous ion and hydrogen peroxide form hydroxyl radicals and iron ions , hydroxyl free radicals and the lignin aromatic vinyl monomer graft copolymerization , and also occur ethylene monomer itself polymerized. In such initiator systems , to achieve a high yield and conversion of lignin , however , a homopolymer of acrylic monomer is 50% to 60%.