粘接性树脂破坏韧性试验方法的探讨

The Investigation of the Testing Method on\;Fracture Toughness of Dental Adhesive Resins

目的 :探讨粘接性树脂modeⅠ破坏韧性试验方法。方法 :以粘接性树脂的种类、试验片规格、试验速度作为影响因素 ,采用双臂牵张试验方法 ,所得试验数据经过统计学分析来考察破坏韧性与各种影响因素的相关性 ,从而对破坏韧性试验方法进行论证。结果 :在龟裂进展过程中 ,破坏韧性值GIC(最大负荷时破坏韧性值 )和GIR(龟裂进展中每时点破坏韧性值 )呈平稳一致的趋势 ,与试验片的龟裂进展量无关 ;粘接性树脂的破坏韧性值与试验片的宽度、厚度、初期龟裂长度及试验速度无显著相关性 ,与粘接层厚度有显著相关性。粘接性树脂SB的破坏韧性值随粘接层厚度的增加而增大。粘接性树脂PV的粘接层厚度为 10 0 μm和 2 0 0 μm时 ,破坏韧性值几乎相同 ;粘接层厚度为 2 0 μm时 ,破坏韧性值呈下降趋势。 结论 :破坏韧性值不受试验片规格大小的影响 ,但受粘接层厚度大小的影响 ,modeⅠ破坏韧性试验方法是有效评价口腔用粘接性树脂粘接性能的新方法。

Objective:The testing method for mode Ⅰ fracture toughness (G\-\{IC\}) of dental adhesive resins was investigated.Methods:The dental adhesive resins were placed between two Co Cr alloy plates to make up test specimen, so test specimen had a metal/adhesive resin /metal construction. The category of adhesive resins, the dimensions of test specimen and testing speed were used as the variants. The testing method for mode Ⅰ fracture toughness (G\-\{IC\}) was investigated by using double cantilever beam (DCB) testing. The correlation between the C\-\{IC\} and each factor was analysed by regression analysis.Results:In all test specimens, it was found that the values of fracture toughness (G\-\{IC\}, G\-\{IR\}) at the process of crack propagation were nearly constant. Therefore, it was found that fracture toughness (G\-\{IC\}) at maximal load might only be measured to evaluate an adhesive resin. On the values of G\-\{IC\}, there was no effect from the dimensions of the test specimens, width (b=3,5 mm), thickness (2h\-m=2,4 mm), initial crack length (a\-0=10～19 mm) and testing speed(v\-c=0 1 mm/min, 0 2 mm/min). But, it was found that the fracture toughness was influenced by thickness of adhesive layer (h\-r). In case of SB, the value of G\-\{IC\} had a tendency to increase as the adhesive layer became thicker, and then the crack propagating area observed as cohesive failure became remarkably rougher. In case of PV, the values for h\-r=100 and 200 μm were similar, however, that for h\-r=20 μm somewhat decreased resulting in an interfacial failure. By the way, cohesive failures of h\-r=100 and 200 μm were observed as similar flat surfaces.Conclusion:Fracture toughness was not influenced very much by the dimensions of test specimen, but was influenced by thickness of adhesive layer. Thus, it was recognized that this testing method was more effective for evaluating the adhesive resin.