Studies On Chitosan/CPAM Via Aqueous Dispersion Polymerization

Cationic polyacrylamide with cation group could prove significant special effects, so it had been one of the hot researchs in the main researeh areas of functional polymers. Aqueous dispersion polymerization was a new excellent method which had many advantages such as simplicity in process, solvent-free and so on. The stabilizer was important to the aqueous dispersion polymerization as the key factor in the system, the most commonly used stabilizers were synthetic copolymers and homopolymers; but the natural polymers was not reported. In the thesis, chitosan(Cts) was introduced into aqueous dispersion polymerization of cation polyacrylamide as new dispersant. The preparation of environment-friendly aqueous dispersion of cationic polyacrylamide were detailedly investigated. The structure of copolymer was characterized by various methods. Meanwhile, the performances of the coagulation-flocculation were discussed.1. This research selected chitosan as dispersant stabilizer, acrylamide(AM) and cationic monomer dimethylaminoethyl methacrylate methyl chloride (DMC) as main raw materials, and azo-compounds(V50) as initiator, the cationic polyelectrolyte of Cts/CPAM was synthesized by aqueous dispersion polymerization in the sodium chloride solution with weak acid.2. The effects of varying factors on the polymerization, the product character (i.e. molecular weight) and the stability of the system were investigated including the dosage of monomers, dispersant, sodium chloride and the dosage of initiator, the mass ratios of AM/DMC, the reaction temperature and so on.3. By the orthogonal experiment, the optimum conditions of synthesis were determined as follows, the dosage of dispersant 1.50 %, the concentration of inorganic salt 17.50 %, the concentration of initiator 0.042‰and the react temperature 60.0℃. 4. The dispersion copolymers were characterized with Fourier Transform Infra-Red (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetry analysis (TGA). The property of the copolymer was researched with microscopic viewpoint. Combined with previous discussion of the single factor experiment, it was speculated that Cts was grafed to the copolymer of AM and DMC in the reaction process, making the system generated self-stabilization. And the copolymer particles were smaller and homogeneous, its thermal stability was good.5. The high molecular weight Cts/CPAM was used as flocculant to treat kaolin waste water. The influences of the concentration of the copolymer, the temperature and stirring rate etc. on the flocculation efficiency were investigated. It was found that the dosage was few, but the flocculating effect was good. In addition, the flocculating property had the advantages, such as small pH effeet and wide temperature range.6. The flocculating mechanism of the copolymer was discussed based on the floc form. The results illustrated that the flocs of kaolin treated by the coplymer had obviously features of fractal, and the performance of absorbing and bridging was well between microflocs and flocculated aggregates.