Biobased Semiaromatic Polyamides Derived from Dimethyl Furan-2,5-Dicarboxylate: Influence of the Composition on Their Properties

Aiming at biobased semiaromatic polyamides with high performance from furan derivatives and studying the effect of the ratio of furan rings to benzene rings on the properties of polyamide, a series of poly(decamethylene terephthalamide/decamethylene 2,5-furandicarboxamide) copolyamides (PA10T/10Fs) with the furan ring content ranging from 0 to 100 mol % were prepared from 2,5-furandicarboxylic acid derivatives, terephthalic acid, and 1,10-decanediamine via a two-step polymerization method. Their molecular weight, intrinsic viscosity, composition, and chemical structure were determined using an Ubbelohde viscometer, gel permeation chromatography, Fourier transform infrared spectroscopy, and nuclear magnetic resonance. The properties of PA10T/10Fs were characterized by X-ray diffraction, differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis, thermal deformation temperature measurement, heat deflection temperature measurement, tensile measurement, notched impact test, and water absorption measurements. The results showed that the target products had been successfully prepared, the PA10T/10Fs with a 10F content of no more than 20 mol % were crystalline, and these copolyamides exhibited comparable heat resistance and elevated tensile strength and elongation at break with those of the PA10T homopolymer. With the further increase of the 10F content, PA10T/10Fs turned amorphous gradually, together with improved transparency, indicating that the intermolecular hydrogen bond was effectively suppressed, which was also supported by density functional theory (DFT) calculations, and the heat resistance and tensile strength decreased slightly, but the elongation at break increased; moreover, the increased furan ring content in PA10T/10Fs resulted in a lower notched impact strength and increased water absorption.