Abstract:In this study, a microwave-sensitive solid acid catalyst was successfully synthesized from sweet potatoes via a simple process.The catalyst was proven to have superior microwave-sensitive and homogeneous properties.The physicochemical properties were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Fourier-transform infrared spectra (FT-IR), thermogravimetric (TGA), scanning electron microscope (SEM) and elemental analysis (EA). Results showed that the total acid density and specific surface area for the catalyst were 6.35 mmol/g and 78.35 m 2 /g, respectively. The elemental sulfur content reached 7.449% after sulfonation and the catalytic activity could reach over 91% within 30 min with microwave power density of 1.0 W/mL. The catalytic reaction temperature should not exceed 200 • C, as shown in TGA curve, and the moisture content in the oil raw material should be within 1%-2%. The catalyst deactivated gradually to 64.38% after reutilization five times, but the catalytic activity could be simply regenerated by re-sulfonation, albeit slightly reduced (87.56%). The shift of diffraction peaks in the XRD patterns and new absorption peaks at 619.98 and 1190.49 cm −1 of FT-IR spectra demonstrated that the -SO 3 H group was effectively attached to the catalyst. The SEM images displayed a loose and porous amorphous structure in the end catalyst.

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Biodegradable polymers such as poly(3-hydroxybutyrate) (PHB) and polycaprolactone (PCL) blends are considered as potential replacements for non-degradable polymers, however, their brittleness is an obstacle for their full realization in biomedicine and food packaging. Here, new biodegradable plasticizers are developed to improve the physicochemical properties of PHB and PCL blends. These plasticizers are synthesized through a one-step random copolymerization process using different mass ratios (1:1, 2:1, 1:2) of β-butyrolactone (HB) and ε-caprolactone (CL) monomers. Plasticizer with larger content of CL segments (1:2) shows a thermal stability higher than other ratios. The addition of plasticizers to PHB/PCL blends enhances the elongation at the break of PHB 50 /PCL 50 blend at least 4 to 6-fold compared to pure PHB. This process also decreases the melting point and crystallization of PHB/PCL blends which are pivotal for thermal processing, such as extrusion, while no adverse impact on the tensile strength and elastic modulus of blends was observed.