Effect of organically modified Ni–Al layered double hydroxide loading on the thermal and morphological properties of L-methionine containing poly(amide-imide) nanocomposites
This work deals with the synthesis of an organically modified Ni–Al layered double hydroxide (LDH) and the effect of the LDH loading on the thermal and morphological behavior of poly(amide-imide)/Ni–Al LDH nanocomposites. Modified Ni–Al LDH was synthesized by a co-precipitation reaction of Ni(NO3)2·6H2O, Al(NO3)3·9H2O and N,N′-(pyromellitoyl)-bis-L-methionine under ultrasonic irradiation in a short time. The X-ray diffraction (XRD) analysis reveals that the d-spacing value of the modified LDH increases to 2.00 nm from 0.76 nm for the unmodified LDH, which confirms the insertion of a diacid molecule into the LDH interlayers. L-Methionine containing poly(amide-imide) blends with various modified-LDH content (2, 4 and 8 wt% with respect to polymer) were prepared in ethanol under sonication. The structural properties and the thermal behavior of the modified-LDH and polymer based nanocomposites were characterized by XRD, field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectra and thermogravimetry analysis (TGA) techniques. TEM and FE-SEM results revealed the exfoliated modified-LDH in the polymer matrix. According to the TGA results, the prepared nanocomposites show significantly improved thermal stability at higher temperature because of the homogeneous and good dispersion of modified LDH in the polymeric matrix.