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The performance of epoxy adhesives on clean and oil-contaminated metal substrates

Thesis/Dissertation ·
OSTI ID:7043873
The performance of a two part epoxy adhesive cured using amidoamines on clean and oil-contaminated cold-rolled steel (CRS) and electrogalvanized steel (EGS), was studied using a screening test, a lap-shear test and a modified Boeing wedge test. X-ray photoelectron spectroscopy (XPS), Attenuated total reflection (ATR) and reflection absorption infrared spectroscopy (RAIR) were used to analyze the failure and fracture surfaces. The XPS results indicated that epoxy adhesives prepared using amidoamine curing agents with low amine numbers were able to displace the oil from the CRS and EGS surface, but adhesives prepared with amidoamine curing agents with high amine numbers were not. However, it was also shown that the pure curing agents could displace the oil from CRS and EGS surfaces based on thermodynamic calculations; this was confirmed by a simple XPS experiment. From ATR analysis, it was determined that the oil was effectively absorbed as deep as 2.0 microns into the CA-1 cured adhesive from the CRS surface. The oil was mostly present in the first 0.3 microns thick layer of adhesives near the CRS surface. The oil was mostly present in the first 0.3 microns thick layer of adhesives near the CRS surface for CA-2 and CA-3 cured adhesives. The effectiveness of the oil-displacing behavior of the adhesive systems used was related to the amounts of curing agents used, the diffusion rates of oil into the adhesives and, most importantly, the curing rates of the adhesives. The results from lap-shear and wedge tests showed that durable and strong bonds on oiled CRS and EGS surfaces were obtained using amidoamine curing agents with relatively low amine numbers and by blending silane coupling agents into the adhesives.
Research Organization:
Cincinnati Univ., OH (United States)
OSTI ID:
7043873
Country of Publication:
United States
Language:
English