Self-metathesis of fatty acid methyl esters (FAMEs) from natural oils and commercial oleic acid was carried out using a microwave reactor in solvent-free conditions. Self-metathesis products were further identified and quantified by gas chromatography–mass spectroscopy (GC–MS) and gas chromatography–flame ionization detector (GC–FID). Conversion of ∼50% was achieved within a short span (∼2 min) in the presence of 0.05 mol % Hoveyda–Grubbs second generation catalyst (HG2) giving an equilibrium mixture of alkenes, α,ω-diester, and FAMEs. Highly pure dimethyl-9-octadecene-1,18-dioate (diester) was separated, and the desired quantity of it was reduced to 9-octadecene-1,18-diol (diol). Condensation polymerization of diester and diol as monomers was performed using conventional heating, microwave irradiation, and microwaves coupled with conventional heating. Characterization and analysis of synthesized biopolyesters were carried out using different techniques including nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), and tensile tests. Polyesters with the highest molecular weight of 337 kDa, ∼50 °C melting point, degradation temperature of about 400 °C, and the maximum strength of ∼5.5 MPa were obtained. These materials have great future potential to be used in different applications as a substitute of nonrenewable polyesters.

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.

In this study, a new strategy for making biopolyethers from plant oil derived monomer (α-olefin) was developed using microwave irradiation, conditions were optimized and compared with a conventional method.

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