Development And Performance Of Base Adhesive For Strain Gauge Load Cell

Strain gauge load cell is widely used in mechanical high precision measurements. At present, load cell design, manufacture and test in china, especially the strain gage backing material are laggard a lot. To manufacture high precision, long-term stability strain gauge, a novel base adhesive was developed and its cure kinetics and performance were studied in this paper. The main results are summarized as follows:First, formulation tailoring and curing process of epoxy resin adhesive have been studied, and the peel strengths were tested. The curing temperatures are obtained following the result of curing reaction heat flow tested by DSC. The results showed that the modified epoxy resin was satisfied, and could stick well to constantan alloy. The tests of resistance to hydrothermal ageing showed that the adhesive has excellent resistance to weathering.Second, the cure kinetics of epoxy resin adhesive was studied by both in-situ and ex-situ Fourier transform infrared (FTIR) spectroscopy. From fitting to experimental data the kinetics parameters were estimated and the equation among cure time, cure temperature, and conversion of epoxide were obtained, which will be greatly useful in deciding the epoxy resins cure process. The research also found that ex-situ FTIR is more accurate than in-situ FTIR as regard to the time term in describing the kinetics. The two methods are mutually complementary.Third, the glass transition temperature of base adhesive was determined by dynamic mechanical analysis (DMA) and thermal properties were determined by thermal gravimetry (TG). And the relative thermal stability of function groups was investigated by FTIR. The result showed that methyl and methylene group are the relative unstable function groups and are liable destroyed under high temperature.Forth, the glass transition temperature, creep and strain recovery of base adhesive were determined by dynamic mechanical analysis (DMA). The influences of temperature and stress imposing on creep were also discussed respectively. Strain and strain recovery tests showed that the base adhesive has a good recovery percentage and fulfill the requirements of strain gauge load cell.