| In this paper, the semi-continuous emulsion polymerization process was used to obtain polyvinyl acetate emulsion of theoretical solid content of40%, which separately adopt carboxymethyl cellulose, hydroxyethyl cellulose, waxy starch, Alkali-modified waxy as protective system.The influence of the content of protective colloid to emulsion properties was studied, and the emulsion stability, emulsion viscosity, particle size, water absorption, compression shear strength, the microscopic state of the emulsion, the emulsion rheological properties were tested.The PVAc emulsion synthesized with SiO2/PVA as protective colloid show good polymerization stability, storage stability and dilution stability.The viscosity of emulsion was decreased, and the water absorption of emulsion film was increased firstly and then decreased with the increase of the content of SiO2particle.The emulsion particle size distribution was within the range of220.4nm-471.0nm. The compression shear strength was increased firstly and then decreased with the content of SiO2particle, and the maximum value was12%higher than the control.SEM results indicated that SiO2particle adsorbed the surface of latex particles, and turn the rounded particle to irregularity.The PVAc emulsion synthesized with Carboxymethyl cellulose and hydroxyethyl cellulose as protective colloid, the synthesis emulsion has good stability.The water absorption of emulsion film was increased with the content of CMC and was decreased with HEC.The viscosity of emulsion was increased by increasing protective colloid, and the particle size was increased with increasing of the content of HEC; The compression shear strength of emulsion with CMC was8.0-9.7MPa and the compression shear strength of emulsion with HEC was7.5～11.9MPa. The emulsion micro-dispersed is good and particle shape rules uniformly dispersed.The PVAc emulsion showed well stability with waxy starch and alkali-treated waxy starch as protective colloid. With the increasing of the content of starch, the water absorption of emulsion film was decreased first and then increased; the viscosity of emulsion was increased. The dry compression shear strength of the emulsion using waxy starch as protective colloid was between8.0MPa～9.8Mpa and when the alkali treatment is protective colloid in emulsion systems,compressive shear strength was between7.4～10.2Mpa;waxy starch.The particle of PVAc emulsion synthesized with waxy starch and alkali-treated waxy starch showed well micro-separating state.All synthesized emulsion showed the significant symbol of pseudoplastic fluid. Their shear viscosity was increased with the decreasing of shear rate. Appropriate SiO2adding in the emulsion could stable the network structure and increase the shearstress. Both HEC and alkali-modified starch could increase the shear stress. But HEC would increase the consistency index and flow index of emulsion while alkali-modified starch would decrease both consistency index and flow index the priority of flow index by using same content of protective colloid was alkali-treated waxy starch>HEC> waxy starch, and the priority of Spatial structure strength under similar shear stress was HEC> waxy starch> alkali-treated waxy starch. HEC is the best of three kinds of protective colloid. |
PDF Full Text Request