Proton magnetic resonance of some polyamides

Abstract

Abstract Proton magnetic resonance of a number of polyamides has been investigated in the 80–410°K. range. Line width and second moment vs. temperature plots for dry specimens of poly(hexamethylene adipamide) and poly(hexamethylene sebacamide) are found to exhibit two transition regions. Saturation with H 2 O or D 2 O lowers the temperature of the principal line‐narrowing process for the above two polymers as well as for poly(decamethylene sebacamide) and shifts part of the second‐moment transition which occurs above room temperature to lower temperatures; in both cases H 2 O has a more pronounced effect than D 2 O. Exchange of the protons, presumably on the amide groups, for deuterium leads to small decreases in line width and second moment at temperature in and below the main transition. N ‐methylation of poly(decamethylene sebacamide) up to 58% causes marked shifts of the principal line‐narrowing process and NMR second moment transition to lower temperatures. The NMR data are found to be in qualitative agreement with dynamic mechanical measurements on similar samples.