A method evaluating the time-course of depth profiles of conversion in thick layers of UV curable resins has been established. This method is based on chasing the curing reaction of the resin as the change of infrared absorbance at the absorption band assigned on its vinyl group, which is put on a horizontal ATR prism equipped in FT-IR spectrophotometer, under UV light irradiation vertical to the prism. From the real-time data at any depths, the time-course of depth profiles of conversion can be pictured. Using a methacrylic acid ester UV curable resin, the present evaluating method was exemplified.

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In the previous paper, the evaluation method of the shear strength of adhesive resins using biaxial testing machine and the cruciform adhesive joint with circular bonded area was studied both analytically and experimentally. In this paper, the validity of this evaluation method was studied for the cruciform joints with a rectangular bonded area. Stress distribution in the adhesive layerof the cruciform joint was calculated using the finite element method. It was confirmed that the von Mises equivalent stress was hardly influenced by the normal stresses, but by the shearing stress. Two kinds of adhesives were investigated using the cruciform joints with a rectangular bonded area. One is the adhesive that follows the von Mises yield criterion and another is one that does not follow it. The cruciform joint was prepared using these adhesives and the biaxial load test was performed. It was observed that the fracture strength of the cruciform joint using the adhesive that follows the Mises yield criterion was approximately constant independent on the loading ratio according to the calculation result. On the other hand, the fracture strength of the joint using the adhesive that does not follow the von Mises yield criterion was not constant. From these results it was concluded that this evaluation method could be useful to estimate changing tendency of adhesive bonded strength depending on the various loading ratio.

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