from the greater peaks intensities of the epoxide ring(∼830 cm−1) and O H groups (∼3400 cm−1) for the nanocomposite compared to the blank sample. Moreover, the C N band(1000–1100 cm−1) intensity decreased in the presence of nanoparticles. According to step 2 of curing reaction (Eq. (2)), the decrease in C N band intensity also shows that nanoparticles limited the curing reaction. The same results have been obtained in our previous work [13]. Nanoparticles could reduce the curing degree by increasing the epoxy/polyamide resins mixture viscosity. Moreover, the curing degree can be negatively affected due to steric hindrance effect of the particles causing a decrease in reaction of functional groups of epoxy resin and polyamide hardener[31].Fig. 8-a shows that the etheric band intensity decreased and O H band intensity increased for the blank epoxy coating exposed to salt spray test. However, the intensity of the mentioned bands did not significant change for the coating loaded with 3.5 wt%nanoparticles (Fig. 8-b). The increase in O-H band intensity and also the decrease in etheric band intensity show that the hydrolytic degradation of the epoxy coating decreased in the presence of nanoparticles. The mechanism of coating hydrolytic degradation is described by Eq. (5) [31].
(5)
Eq. (5) shows that the hydrolytic degradation of the epoxy coating causes etheric linkage breakdown and hydroxyl groups formation [21]. Results show that addition of nanoparticles caused lower hydrolytic degradation of the coating compared to the neat epoxy coating. Two mechanisms may be responsible for the lower coating degradation observed in the presence of the nanoparticles [31,32]. As it has been previously discussed, there are both low and high cross-linking density areas on the coating surface
from the greater peaks intensities of the epoxide ring(∼830 cm−1) and O H groups (∼3400 cm−1) for the nanocomposite compared to the blank sample. Moreover, the C N band(1000–1100 cm−1) intensity decreased in the presence of nanoparticles. According to step 2 of curing reaction (Eq. (2)), the decrease in C N band intensity also shows that nanoparticles limited the curing reaction. The same results have been obtained in our previous work [13]. Nanoparticles could reduce the curing degree by increasing the epoxy/polyamide resins mixture viscosity. Moreover, the curing degree can be negatively affected due to steric hindrance effect of the particles causing a decrease in reaction of functional groups of epoxy resin and polyamide hardener[31].Fig. 8-a shows that the etheric band intensity decreased and O H band intensity increased for the blank epoxy coating exposed to salt spray test. However, the intensity of the mentioned bands did not significant change for the coating loaded with 3.5 wt%nanoparticles (Fig. 8-b). The increase in O-H band intensity and also the decrease in etheric band intensity show that the hydrolytic degradation of the epoxy coating decreased in the presence of nanoparticles. The mechanism of coating hydrolytic degradation is described by Eq. (5) [31].(5)Eq. (5) shows that the hydrolytic degradation of the epoxy coating causes etheric linkage breakdown and hydroxyl groups formation [21]. Results show that addition of nanoparticles caused lower hydrolytic degradation of the coating compared to the neat epoxy coating. Two mechanisms may be responsible for the lower coating degradation observed in the presence of the nanoparticles [31,32]. As it has been previously discussed, there are both low and high cross-linking density areas on the coating surface
การแปล กรุณารอสักครู่..