Bioplastics with a wide range of mechanical properties were directly obtained from industrially processed edible vegetable and cereal wastes. As model systems, we present bioplastics synthesized from wastes of parsley and spinach stems, rice hulls, and cocoa pod husks by digesting in trifluoroacetic acid (TFA), casting, and evaporation. In this way, amorphous cellulose-based plastics are formed. Moreover, many other natural elements present in these plants are carried over into the bioplastics rendering them with many exceptional thermo-physical properties. Here, we show that, due to their broad compatibility with cellulose, amorphous cellulose can be naturally plasticized with these bioplastics by simply mixing during processing. Comparison of their mechanical properties with that of various petroleum based synthetic polymers indicates that these bioplastics have equivalent mechanical properties to the nondegrading ones. This opens up possibilities for replacing some of the nondegrading polymers with the present bioplastics obtained from agro-waste.

A method consisting of the alkaline hydrolysis of tomato pomace by-products has been optimized to obtain a mixture of unsaturated and polyhydroxylated fatty acids as well as a non-hydrolysable secondary residue. Reaction rates and the activation energy of the hydrolysis were calculated to reduce costs associated with chemicals and energy consumption. Lipid and non-hydrolysable fractions were chemically (infrared (IR) spectroscopy, gas chromatography/mass spectrometry (GC-MS)) and thermally (differential scanning calorimetry (DSC), thermogravimetric analysis (TGA)) characterized. In addition, the fatty acid mixture was used to produce cutin-based polyesters. Freestanding films were prepared by non-catalyzed melt-polycondensation and characterized by Attenuated Total Reflected-Fourier Transform Infrared (ATR-FTIR) spectroscopy, solid-state nuclear magnetic resonance (NMR), DSC, TGA, Water Contact Angles (WCA), and tensile tests. These bio-based polymers were hydrophobic, insoluble, infusible, and thermally stable, their physical properties being tunable by controlling the presence of unsaturated fatty acids and oxygen in the reaction. The participation of an oxidative crosslinking side reaction is proposed to be responsible for such modifications.

A water-based process to convert vegetable waste into bioplastic films with appealing properties for packaging.

Nowadays, the materials commonly used to fabricate thermoelectric devices are tellurium, lead and germanium. These materials ensure from one side the best thermoelectric performances, but exhibit drawbacks in terms of availability, sustainability, cost and manufacturing complexity. Moreover, they do not guarantee a safe and cheap implementation in wearable thermoelectric applications. Here, p-and n-type flexible thermoelectric textiles are produced with sustainable and low-cost materials through green and scalable processes. Cotton is functionalized with inks made with biopolyester and carbon-nanomaterials. Depending on the nanofiller, i.e. graphene nanoplatelets, carbon nanotubes or carbon nanofibers, positive or negative Seebeck coefficient values are obtained, achieving also a remarkable value of electrical conductivity of 55 S cm -1 using carbon nanotubes. The best bending and washing stability are registered for the carbon nanofibers-based biocomposites, which increase their electrical resistance by 5 times after repeated bending cycles and only of the 30% after washing. Finally, in-plane flexible thermoelectric generators are fabricated and characterized coupling the best p-and n-type materials, achieving an output voltage of ~ 1.65 mV and a maximum output power of ~ 1.0 nW by connecting only 2 p/n thermocouples at a temperature difference of 70°C.