Compressive Creep of Composite Resins in Water

本研究的目的是测定复合树脂的蠕变性能以及填料含量对复合树脂的影响。在不同应力水平下，非商用复合树脂在水中500h的压缩蠕变，得到不同时间的蠕变应变与压缩应力水平之间的线性回归。由回归方程可以预测复合材料在500h后达到吸水平衡时的蠕变应变，并由线性回归计算出吸湿膨胀应力。复合材料在吸水平衡时的最大吸湿膨胀应力为0.7 kg/mm2，不同填料含量的复合材料在不同应力水平的吸水平衡水中也进行了压缩蠕变。相同填料含量的复合材料在500h后的蠕变应变与试件屈曲应力水平内施加的压应力水平成正比。在不同时间，蠕变应变与压应力水平之间也得到了线性回归。吸湿膨胀产生的最大应力为0.4-0.5 kg/mm~2，与上述复合材料相近。复合材料的吸水率随压缩应力水平的增加而降低，因为试件的体积应变也与压缩应力水平的增加成正比。但在高纤维含量的复合材料中，吸水率在体积应变较小的低应力范围内几乎不变。

The objective of this study is to determine the creep properties and the effects of the filler content on the composite resins.The compressive creep of acommercially available composite resin under various stress levels in water for 500 h. Linear regressions were obtained between the creep strains and the compressive stress levels at various hours. It is possible to predict the creep strain of the composite from the regression when it reaches water absorbed equilibrium after 500 h. The stress of the hygroscopic expansion was calculated from the linear regressions. The maximum stress due to the hygroscopic expansion of acomposite was 0.7 kg/mm^2 at equilibrium of the water absorbed of a composite.The compressive creep of the composite resins with various filler contents were also conducted in water equilibrium water absorbed with several stress levels. The creep strain after 500 h in each composite with same filler content was in proportion to the applied compressive stress levels within the buckling stress level of the specimen. Linear regressions were also obtained between the creep strains and compressive stress levels at various hours. The maximum stress due to the hygro- scopic expansion was 0.4-0.5 kg/mm^2. The value is similar to the value of the com posite above mentioned.The water sorption of the composites decreased as the compressive stress level increased, because the volumetric strain of the specimen also was proportional to the increase of the compressive stress level. But in the composites with a high fillet content, the water sorption was almost constant in the range of the low stress level where the volumetric strain was small.