Introduction: Modified epoxy suitable for ultraviolet (UV) curing is prepared by using organic silicon toughening. The curing kinetics of the composite are studied by dielectric analysis (DEA), and the two-phase compatibility of the composite is studied by scanning electron microscopy (SEM). Methods: The tensile properties, heat resistance, and humidity resistance of the cured product are explored by changing the composition ratio of the silicone and the epoxy resin. Results: SEM of silicone/epoxy resin shows that the degree of cross-linking of the composites decreases with an increase of silicone resin content. Differential thermal analysis indicates that the glass transition temperature and the thermal stability of the composites decrease gradually with an increase of silicone resin content. The thermal degradation rate in the high temperature region, however, first decreases and then increases. In general, after adding just 10%-15% of the silicone resin and exposing to light for 15 min, the composite can still achieve a better curing effect. Conclusions: Under such conditions, the heat resistance of the cured product decreases a little. The tensile strength is kept constant so that elongation at breakage is apparently improved. The change rate after immersion in distilled water at 60°C for seven days is small, which shows excellent humidity resistance.

Poly(urethane urea) elastomers with graded structure in the thickness direction were prepared using gradient temperature molding. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were used to characterize the gradual change of structures within the elastomers. The degree of microphase separation in prepared samples would increase gradually with the increase of the curing temperature. Moreover, the interfaces between hard and soft segments also exhibit gradual changing trend, becoming more significant along the same direction. Effect of chain extender content and magnitude of temperature gradient on structure gradient was investigated. Mechanical properties of graded poly(urethane urea) elastomers were also studied.

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Abstract-There were vertical welding was operated with general SHS welding rods based on Fe-base which was developed by our organization in this paper. Not only experimental phenomenon in the process of welding include form of molten bath and flow of fusion solder, but also experimental phenomenon after welding include macrograph form of welded seam and slag form were observed and analyzed. The currently main problems for manual SHS vertical welding were analyzed, and the reasons which caused the above phenomenon was discussed from two aspects of macroscopic and microscopic. The text summary finally points out the significance and function of the failure test. The important significance and impact for the experiment were pointed out in the end of the paper.