FTIR study of ageing epoxy resin reinforced by reactive graphitic nanofibers

Abstract

We previously developed a novel modified epoxy matrix for macrocomposites using reactive graphitic nanofibers (r-GNFs), which showed improved mechanical properties. This article is devoted to study the efficacy of the r-GNFs against the damage due to exposition of the matrix to hygrothermal environment and UV radiation. Moisture sorption characteristics of the pure epoxy and nanoepoxy were investigated and all kinds of matrices showed similar absorption behavior. Both diffusion and relaxation processes in sorption were observed. DSC curves of nonaged specimens of all concentrations confirmed that samples were not fully cured and r-GNFs lowered the curing degree. The effects of ageing were studied through the changes of molecular conformation by Fourier Transform infrared spectroscopy (FTIR). The results show that UV radiation assists in post-curing of the matrices. Hydroxyl unit, carbonyl unit, and epoxide unit were chosen to study the degradation. It is observed that the degradation due to UV radiation is more severe compared with that due to hygrothermal expose. It also reveals that r-GNFs resist the degradation of the epoxy resin; particularly, the nanoepoxy with 0.3 wt % of r-GNFs has the highest ageing resistance, which is in agreement with our previously tested results of mechanical properties.

Effect of Modification with Various Epoxide Compounds on Mechanical, Thermal, and Coating Properties of Epoxy Resin

“…Epoxy group showed typical bands at the regions of 830, 913, and 1250 cm −1 [20]. The absorption band at 913 cm −1 was used for the determination of curing degree because a band at 830 cm −1 possibly overlapped with a C-H vibration band of aromatic ring [21,22]. As intensity of the absorption band at 913 cm −1 decreased, curing degree increased.…”

Preparation of epoxy composites with CTAB-modified BN and MWCNTs

“…The characteristic bands of epoxy groups lie in the range of 830, 913, and 1,250 cm 21 [26]. The band in the 830 cm 21 region may coincide with the vibration of two adjacent hydrogen atoms of the benzene ring; however, the band in 913 cm 21 region does not exhibit interference [27,28]. Therefore, although the degree of cure increases, the intensity of the 913 cm 21 band decreases, which indicates that the band at 913 cm 21 is sensitive to epoxy group changes and matches the Beer-Lambert law [29,30].…”

Epoxy resin nanocomposites reinforced with ionized liquid stabilized carbon nanotubes

“…Figure 4 shows the DSC curves of the nanocomposites with 1 wt% f-CNT loading and pure epoxy. The glass transition temperatures of the polymer matrix depend on the free volume of the polymer, which is correlated to the affinity between the fillers and the polymer matrix [31,32]. Molecular motion in the bulk state depends on the presence of the vacancies or voids.…”

“…However, the feature at 913 cm −1 exhibits no interference [33,37]. The intensity of the band at 913 cm −1 decreases with increasing degree of curing, which means that the band at 913 cm −1 can sensitively reflect the change of the epoxy groups and better obeys the Beer-Lambert law [32,36]. According to the Beer-Lambert law, the absorption peak at 1616 cm −1 of a benzene ring can be regarded as the internal standard, so the degree of curing can be determined from…”