Thermal Imidization of the Precursor of a Liquid Crystalline Polyimide

Abstract

Imidization of the precursor of a liquid crystalline polyimide was investigated using modulated differential scanning calorimetry (MDSC), Fourier transform infrared (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), and thermogravimetric analyzer (TGA) coupled to FTIR (TG‐IR). The FTIR study revealed that the rate and degree of imidization are functions of curing temperature and time. Imidization proceeds in two stages under isothermal condition. The initial weight loss up to 250 °C as observed from TGA was due to thermal cyclization, i.e., imidization process. The XPS analysis shows that the poly(amic acid) has two nitrogen 1s species at 400.3 and 399.2 eV possibly due to the isomerism of the dianhydride carbonyl, while liquid crystalline polyimide shows only a single nitrogen 1s species at 400.8 eV due to imide species.PLM micrograph of PAA (at 280 °C) after imidization.magnified imagePLM micrograph of PAA (at 280 °C) after imidization.

Structuring and characterization of a novel highly microporous PEI/BMI semi-interpenetrating polymer network

“…BMI-EtOH S and L which could be attributed to ethoxy group as illustrated elsewhere (Table 4) [30]. This peak (b) might also be attributed to OaC-O or OaC-N in amide group [31]. Due to the absence of this peak in PEI-EtOH spectrum, it appears that BMI has a major role in the ethoxy substitution, which probably occurred with the maleimide group in addition to the formation of amic acid (amideC carboxylic acid) resulting from imide cleavage.…”

BPDA-PDA Polyimide: Synthesis, Characterizations, Aging and Semiconductor Device Passivation

“…The characteristic IR absorption peaks were assigned thanks to previous works [17,[26][27][28][29][30][31][32][33][34][35][36]. Usually, PAA spectra are compound of the N-H stretch bonds at 2900-3200 cm -1 , the C=O carbonyl stretch from carboxylic acid at 1710-1720 cm -1 , the symmetric carboxylate stretch bonds at 1330-1415 cm -1 , the C=O carbonyl stretch of the amide I mode around 1665 cm -1 , the 1540-1565 cm -1 amide II mode and the 1240-1270 cm -1 band due to the C-O-C ether aromatic stretch (if present in the monomer).…”

Polyimide fibers prepared by a dry‐spinning process: Enhanced mechanical properties of fibers containing biphenyl units

“…13 When it was heated to 300 8C, the characteristic peaks of the sample at 1370 and 1770 cm 21 were attributed to the CAN stretching and C@O symmetric stretching of the imide ring, respectively; these peaks illustrated the formation of fully imidized PI-1 fibers. 14,15 In our last work, 16 we reported that the peak at 1370 cm 21 could be used to quantitatively calculate the ID by the following equation because of its very strong characteristic features:…”