Synthesis and characterization of polyamides X 18

Step heating melt polycondensation was adopted in the preparation of polyamides based on 1,16-octadecane diacid and alpha,omega-(CH2)(2u), diamines (n = 1-6). The structure was confirmed by various spectroscopic techniques (IR, Raman, H-1-NMR, and C-13-NMR). High molecular masses were obtained only in the presence of an excess of diamine and when the diamine possessed low volatility. The molecular masses were between (0.94 and 2.1) x 10(4) Da for all polyamides under consideration. An excellent correlation between size exclusion chromatography and H-1-NMR data was demonstrated in the measurement of the degree of polymerization. The melting temperatures of the polyamides decreased from polyamide 12 18 to polyamide 2 18 as the amide density along the molecular chain declined. No significant variation was observed in the glass-transition and decomposition temperatures of the polyamides that were obtained.