| In this article soap-free emulsion copolymerization of chlorotrifluoroethylene(CTFE) and vinylacetic acid(VAc) with undecednoic acid Sodium(NaUA) were be studied deeply using KPS as initiators, soap-free fluoro-emulsion was prepared. The solid content and copolymer's fluoro-content of soap-free fluoro-emulsion are 21% and 24.66%. The average molecular weight of the copolymer( Mn) is 8732. The fluoro-emulsion can maintain stable at least 6 months without delamination and gel being observed. According to the study of the factors effected on the polymerization, NaUA was the main factor maintain the stability of soap-free emulsion. With the increasing of mass of NaUA, polymerization degree and copolymer's fluoro-content and solid content added accordingly. Because of same reason, average molecular weight of the copolymer and viscosity of fluoro-emulsion increased. The contact angle of fluoro-emulsion latex film also decreased with the mass of NaUA added because the mass of NaUA made copolymer have wetness property better. The result of analysis to guanularity and observed through transmission electron showed that the diameter and the number of particles were affected by the content of NaUA mostly and the emulsion have particles with uniform diameter. When the mass ration of VAc/NaUA was 80/20, the diameter was about 83nm. The enhance of the ionic strength and increasing of ratio of hydrophilic/ lipophilic of polymer can increasing the stability of emulsion. In order to decreasing the pressure of polymerization systerm, the soap-free emulsion copolymerization of fluoro-monomer with redox intiators at lower temperature were studied. The pressure of polymerization can changed from 1.35MPa to 0.72MPa by this methods. Applied to the cement to change the quality of cement with tradition emulsion of PVAc, soap-free emulsion of P(VAc/NaAA) and soap-free fluoro-emulsion with KPS initiator. It showed soap-free fluoro-emulsion can improve the fluidity and bending... |
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