Synthesis and Characterization of Unsaturated Biobased-Polyamides from Plant Oil

Abstract

This study describes the synthesis and characterization of two biobased polyamides, PA (DMOD-PXDA) and PA (DMOD-DETA), from dimethyl 9-octadecenedioate and p-xylylenediamine or diethylenetriamine. The effect of traditional (TH) and microwave heating (MH) on synthesis conditions, thermal properties, and crystalline structures of the polyamides was compared. Furthermore, thermomechanical and mechanical properties of polyamide films were studied. Solid-state carbon nuclear magnetic resonance spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy were used to characterize the polyamides. All polyamides showed a melting point of around 190 °C with higher melting points for the traditionally polycondensed ones. Wide-angle X-ray scattering indicated γ-crystals as the primary crystalline forms produced under microwave heating, whereas amorphous and α-crystal phases were mainly produced under traditional heating. Dynamic mechanical analysis showed the highest glass transition temperature for TH-PA (DMOD-PXDA) at 78 °C. PA (DMOD-PXDA) films exhibited comparable tensile strengths, but the percent elongation at break of the TH-PA (DMOD-PXDA) film was higher than that of the MH-PA (DMOD-PXDA) film. Higher values for tensile strength and percent elongation at break were also observed for TH-PA (DMOD-DETA) and MH-PA (DMOD-DETA) films, respectively. These biobased polyamides have a great potential to be used in different applications as substitutes for petroleum-based polyamides.