The Study On The Curing Kinetics And The Compression Properties Of Polysulfide Rubber Based On Its "Click" Chemistry

Polysulfide (PSF) rubber as a widely used material has experienced several decades' development; to date, it still plays important applications on sealant and adhesive for its good resistance to the solvent, chemicals, environment, and ultraviolet, also has good properties at low temperature. Compared with new materials as polyurethane and polysiloxane, it still has many advantages.Although the PSF material has been well developed, it still remains huge challenge to apply PSF on the different aspect of applications. Focused on this old material, this paper supplied new methodologies and approaches to intensively study the PSF system and solve the current difficulties problems. The application of PSF still faces these problems as follows:(1) The curing rate of liquid PSF rubber has considerable changing within the room temperature range, pH values and so on. There has no efficient method to in-situ monitoring the curing process till now on, which could be significant meaningful to determine the time of execution, surface drying and basically cured.(2) With the development of thiol "click" chemistry, it is meaningful to judge if the material containing double bonds can be a potential powerful vulcanizing agent for the PSF rubber and improve the performances of the traditional PSF-metal oxide material.(3) As an oligomer of low molecular weight, PSF with low cross-linking points has limited compression behavior. It is urgent to increase the cross-linking degree and the compression performances, especially for the some circumstances such as long time under water pressure.(4) There has no analysis and efficient calculations for the long-time stress-relaxation and creep deformation of PSF rubber based on the molecular structure theories, neither the prediction for long-time compression deformation.(5)The curing rate before the gelation and thepost curing after gelation have been found great influence on the compression behavior, which has not been researched yet.Aiming at the above-mentioned problems, this dissertation is mainly concerned with the following aspects:(1) The PSF-MnCh curing process was in-situ monitored and the characteristic points on the DEA curves, including beginning time, gel time and the ending time had been determined and verified by various testing methods. Based on DEA method, the influence of the pH values on the curing process was researched.(2) Combined with DEA, rheological dynamic mechanical analysis (DMA), extraction and swelling methods, the curing process of PSF thiol-acrylate click reaction with amine catalyst was studied. The characteristic points were determined and the activation energy was calculated. Influences included reactant chain length, kind and quantity of the amine catalyst, and the reaction temperature were investigated. This reaction is proved to be high speed and efficient.(3) The compression relaxation and deformation were analyzed by the molecular interpretation and theoretical modeling. Base on the stress relaxation results, the long-time compression deformation was predicted by theoretical calculation with good accordance with the experimental results. Multi-functional acrylate was employed to modify the PSF-MnO2 curing system and effectively increased its cross-linking degree and compression properties.(4) The influences of the curing rate and the later period curing on the compression properties were studied and reasonable analyzed by the cross-linking network viscoelasticity theories.Achievements and highlights made in this dissertation including:(1) The research on the PSF thiol and acrylate click chemical supplies a new method for the PSF curing, which breaks through the limitation of the traditional PSF-metal oxide curing system. Using this reaction, the compression performances of PSF sealant has been significantly improved.(2) Through the theoretical analysis and molecular modeling for the relaxation behaviors of PSF network, the long time deformation has been successfully predicted.(3) DEA has been first employed as a convenient and efficient method to in-situ monitor the PSF curing process. The difficult of the in-situ analysis of PSF curing causing by its little exothermicity and long reaction time has been radically solved, which has great significance to the theoretical research and the industrial application.(5) The molecular viscoelasticity theoretical explanation to the curing rate and later period curing influence on the compression behavior has important directive significance for the fundamental researches and applications.