Synthesis Of PAA-g-NPEO Graft Copolymers And Its Evaluation As A Dispersant In Dispersion Polymerization Of Acrylamide Initiated By UV Light

Dispersion polymerization is a useful method to prepare Polyacrylamide (PAM) for its lower media viscosity, convenient heat removal and ability to produce polymer in a easily separable powder form. But in most dispersion systems the amount of dispersant used is very large. Polymerization initiated by UV light can be completed in a short in a short time even under the condition of lower reaction temperature, which is beneficial to the production of high molecular weight polymer. In this paper, photopolymerization have been introduced into homogenous dispersion polymerization system with a designed graft copolymers as the dispersant. The study showed that the advantages of these two methods were combined and the amount of the dispersant used dropped to a lower level. That is of great significances in industry.In chapter two, a series of graft copolymers were obtained by the ultraviolet (UV) initiated precipitation copolymerization of acrylic acid (AA) and PEON-A then were characterized by means of UV, IR, 1H-NMR and GPC analyses. Using these graft copolymers in AM dispersion polymerization, TEM showed that the dispersant could stabilize the dispersion polymerization system effectively. The mechanism of stabilization had also been discussed.Chapter three main relate to the study of dispersion polymerization of AM initiated by UV light. The effects of various polymerization parameters on the dispersion polymerization were systematically investigated. The main result obtained in this chapter are described as follows:1. The evolution of the dispersion polymerization indicated that there was no induction period and 90% conversion could be obtained in 40 minutes. High polymerization rate was also found even at the layer with thickness of several centimeters, The molecular weight of polymer high up to 6.5×106 was produced.2. Solvent polarity is the key parameter to control the particle size. Changing solvent polarity, particles range from 100-800 nm with narrow distribution achieved. Particle size increased with the increase of the monomer concentration, initiator concentration and layer thickness while decreased with the increase of the ratio of the alcohol to water. Dispersant concentration, polymerization temperature and light intensity had little effect on the particle size. The molecular weight of PAM decreased with the increase of the ratio of the alcohol to water, initiator concentration and polymerization temperature. With the increase of the monomer and dispersant concentration, the molecule weight reached its maximum and then drops. Light intensity and layer thickness had little effect on the molecule weight of the polymer.