| Damping materials are widely developed to effectively control the adverse vibration, which seriously harms the production and life of people. In this thesis, the epoxidized natural rubber (ENR)/natural rubber (NR) blend damping materials were prepared by rubber mixer and mixing mill. Their rheological properties, vulcanization properties, mechanical properties and damping properties were studied. The vulcanization process and PVT characteristics of ENR/NR blends were characterized by ultrasonic wave. The research work was as follows:1?ENR/NR blends were prepared by rubber internal mixer and open smelting machine. Early experiments show that it is difficult to form a uniform dispersion system from liquid epoxy resin (EP) and high viscosity NR although EP is cheaper than ENR. The EP/NR mixture is not easily prepared in interruption mixing process. Thus the resultant composite mechanical properties were significantly reduced. In order to solve this problem, ENR,whose viscosity is close to NR, was used to mix with NR to prepared ENR/NR blend rubber.2.The rheological properties of ENR/NR blends were tested by capillary rheometer and Rubber Processing Analyzer (RPA). Capillary rheometer test showed that ENR/NR mixing rubber exhibited lower viscosity at higher shear rate at 60?,the Cross model can describe the change of viscosity with shear rate. With the increase of epoxy degree, the zero shear viscosity (?0) and the relaxation time (?) increased, while the non-Newtonian index (n) decreased.The RPA strain scanning test showed that the storage modulus (G') and loss modulus (G") of NR and ENR/NR showed obvious Payne effect, G' is higher while it more largely decreased for unvulcanized rubber with larger expoxidized degree because aggregation of filler with polar ENR. The RPA frequency sweep test showed that ENR improved the interface compatibility between NR and carbon black corresponding to the increased G' . The rate of rubber vulcanization increased at higher curing temperature or for ENR with larger epoxy degree, but the blend ratio of ENR/NR has little effect on the rate of vulcanization.3.The dynamic mechanical properties and damping characteristics of ENR/NR blend rubber were tested by RPA and Dynamic Mechanical-thermal Analyzer (DMA). The damping performance has been significantly improved and the mechanical properties become more stable for ENR/NR blend rubber;The greater the epoxy degree of ENR, the wider the damping temperature range to the higher temperature especially at large strains. The effective range is -56?+6 ? for ENR-25/NR in comparison with -57?-21 ? for NR.However, there is ineffective damping zone for composite rubber when natural rubber epoxidized to higher degree.4?ENR/NR blends vulcanization process were characterized using ultrasonic wave. Ultrasonic wave equipped on rotorless rheometer was,simultaneously with torque, recorded to characterize the vulcanization of ENR/NR. The resultant curve of ultrasonic velocity versus time and curve of torque versus time were compared to show the feasibility of ultrasonic characterizing such process considering their similarity besides implying its sensitiveness to the variation in microstructure and density. The specific volume and ultrasonic velocity was simultaneously tested on pressure-volume-temperature (PVT)-ultrasonic instrument. The obtained data were well described by linear equation, the sound resistance equation reflecting pressure effect and the equation reflecting temperature effect derived from Tait equation, which suggests that ultrasonic wave can monitor the specific volume.The quantitative relationship between the velocity of sound and the vulcanization temperature was obtained according to the principle of temperature and pressure equivalence. Thus, The specific volume of ENR /NR can be estimated during vulcanization. |
PDF Full Text Request