%A XIAO Dan, CUI Xiaowen, LI Weihua, YAN Deyue
%T Investigation on the Brill transition of polyamide 618
%0 Journal Article
%D 2007
%J Front. Chem. China
%J Frontiers of Chemistry in China
%@ 1673-3495
%R 10.1007/s11458-007-0002-z
%P 6-12
%V 2
%N 1
%U {https://journal.hep.com.cn/fcc/EN/10.1007/s11458-007-0002-z
%8 2007-03-05
%X The Brill transition of even even polyamide 618 was investigated using differential scanning calorimetry (DSC), temperature-dependent wide angle X-ray diffraction (WAXD) and Fourier transform infrared (FTIR). The X-ray diffraction results indicate that the melt-crystallized sample of polyamide 618 transforms from the triclinic unit cell to the pseudo-hexagonal phase in the range of 120 180?C. In this range, the thermograph of polyamide 618 presents a broad endothermal peak. From the FTIR spectra, it was found that during the transition process of polyamide 618, the intensity of the intra-sheet hydrogen bonds becomes weak. At the same time, the CH2 amide bonds twist, and the all-trans conformation of methylene sequences is disordered by inserting the gauche conformation. The CH2 segments are in a mobile state because of the enhanced stretching and twisting vibrations of the C CO and C N bonds.