Abstract
A time–temperature–transformation–viscosity (TTT-η) diagram can reflect changes in the physical states of a resin, which take on significance for the study of the curing process of polyurethane resin lenses. Coupling the differential scanning calorimetry (DSC) test, the curing kinetic parameters of 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI)/2,3-bis((2-mercaptoethyl)thio)-1-propanethiol (BES) polyurethane system were obtained. By phenomenological modeling, the relationships between degree, temperature, and time were obtained. An isothermal DSC test was carried out at 423 K. Based on the DiBenedetto equation, the relationships between glass transition temperature, degree of cure, and time were obtained, and the glass transition temperature was thus correlated with temperature and time. The gelation time at different temperatures was measured by rotary rheometry, and the relationship between gelation time and gelation temperature was established. The time–temperature–transformation (TTT) diagram of H6XDI/BES system was constructed accordingly. Subsequently, a six-parameter double Arrhenius equation was used as the basis for the rheological study. The viscosity was examined during the curing process. The TTT-η diagram was obtained, which laid the theoretical foundation for the optimization and setting of processing parameters.
Highlights
With the rapid development in science and technology, the number of people with myopia is increasing significantly, which promotes the demand for resin lenses
The curing mechanism of the H6XDI/BES system and the time–temperature– transformation–viscosity (TTT-η) diagram play a pivotal role in studying the curing of polyurethane resin lenses
The relevant parameters were calculated based on phenomenological modeling, and the gelation time of the system was measured by rheometry
Summary
With the rapid development in science and technology, the number of people with myopia is increasing significantly, which promotes the demand for resin lenses. The curing mechanism of the H6XDI/BES system and the time–temperature– transformation–viscosity (TTT-η) diagram play a pivotal role in studying the curing of polyurethane resin lenses. Phenomenological modeling and mechanism methods are the main ways to study the curing kinetics of a resin. The relevant parameters were calculated based on phenomenological modeling, and the gelation time of the system was measured by rheometry. The curing parameters were obtained by DSC in combination with phenomenological modeling. The gelation time of the resin system was determined by measuring the storage and loss moduli, and the production technique of the T300/BA9913 system was optimized according to the TTT diagram. Phenomenological modeling was chosen to investigate the curing kinetics of the H6XDI/BES resin system. In combination with the viscosity changes in the system during the curing process, the TTT-η diagram was constructed
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