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Step heating melt polycondensation was adopted in the preparation of polyamides based on 1,16‐octadecane diacid and α,ω(CH2)2n diamines (n = 1–6). The structure was confirmed by various spectroscopic techniques (IR, Raman, 1H‐NMR, and 13C‐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) × 104 Da for all polyamides under consideration. An excellent correlation between size exclusion chromatography and 1H‐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. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1565–1571, 2005

A series of odd-odd polyamides were prepared through step-heating melt-polycondensation of undecanedioic acid with various diamines. The synthesized nylons were characterized comprehensively by means of elemental analysis, fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), Raman spectra, intrinsic viscosity, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The intrinsic viscosities of the prepared polyamides except nylon 3 11 are 0.70 to 0.87 dl g −1 . The melting temperatures of the odd-odd nylons range from 182 to 209 • C. In addition, the thermal mechanical properties of nylons 5 11, 7 11, 9 11 and 11 11 were analyzed using dynamic mechanical analysis (DMA). Nylon 3 11 could not undergo DMA due to its low molecular weight. The glass transition temperatures obtained from DMA are in the range 22-39 • C.  2004 Society of Chemical Industry

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