Direct Transformation of Edible Vegetable Waste into Bioplastics

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..

Low-cost and effective fabrication of biocompatible nanofibers from silk and cellulose-rich materials

Here, we show the production of nanofibrous mats with controlled mechanical properties and excellent biocompatibility by combining fibroin with pure cellulose and cellulose-rich parsley powder agro-waste. To this end, trifluoroacetic acid was used as a common solvent for all of the involved biomaterials, achieving highly homogeneous blends that were suitable for the electrospinning technique. Morphological analysis revealed that the electrospun composite nanofibers were well-defined and defect-free, with a diameter in the range of 65–100 nm. Mechanical investigations demonstrated that the fibrous mats exhibited an increased stiffness when pure fibroin was combined with cellulose, whereas they possessed an increased flexibility when the parsley waste was added to fibroin. Lastly, the produced mats were highly biocompatible, as demonstrated by the promoted proliferation of fibroblast cells. The characteristics of the hybrid fibroin–cellulose nanofibers, in terms of nanoscale topography, mechanical propertie..

Plant-Inspired Polyaleuritate–Nanocellulose Composite Photonic Films

Plant epidermis is a complex composite material composed by the cuticle and the epidermal cells. In order to prevent dehydration the cuticle is a water barrier composed of an outer layer (proper cuticle) connected to the cell wall of the epidermal cells via a complex matrix often referred to as cutinised cell wall, that acts as compatibilizer for the water repellent cutin and the hydrophilic polysaccharides in the cell walls. Here, biomimetic plant epidermis-inspired films with selective reflection properties were prepared by formation of an aliphatic polyester coating on chiral nematic cellulose nanocrystal (CNC) films. Aleuritic acid, a polyhydroxylated fatty acid, was sprayed on CNC films and polymerized by hot-pressing. The micromorphology of the resultant samples was characterized by scanning electron microscopy (SEM). Polarised optical microscopy confirmed the CNCs helicoidal organization in the films, responsible for the reflection of circularly polarised light, before and after the hot-pressing. The chemical analysis by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) confirmed the polymerization of aleuritic acid into polyaleuritate with differences between filter paper and woodpulp substrates that were ascribed to water elimination during polycondensation. The characterization of the mechanical (Young’s modulus and hardness from nanoindentation tests) and hydrodynamic (water uptake and water vapor transmission rate) properties indicated that this process enhances the robustness and waterproof behaviour of CNC films. These properties were comparable to those of commercial and biodegradable materials commonly used in packaging such as polyesters and cellulose derivatives, thus making these natural composite ideal for optically responsive packaging applications.J.A.H.-G. acknowledges the funding by the Spanish “Ministerio de Ciencia, Innovación y Universidades”, project numbers RTI2018-096896-J-I00 and RYC2018-025079-I

Effect of trifluoroacetic acid on the properties of polyvinyl alcohol and polyvinyl alcohol-cellulose composites

Highly stretchable polyvinyl alcohol (PVA) films with a strain at break of around 700% were obtained from solutions in trifluoroacetic acid (TFA). Structural and chemical analysis by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (ATR-FTIR) showed that TFA is retained by PVA via hydrogen bonds between the carboxylic acid groups and the hydroxyl groups of the polymers causing a strong plasticizing effect. Additionally, composites of PVA with cellulose could be developed using TFA as common solvent. The morphological and mechanical properties of the polymer composites could be accurately tuned by modifying the relative concentrations of the two polymers. Data from water adsorption isotherms and wetting measurements indicated that the presence of trifluoromethyl groups in PVA render the composite films relatively hydrophobic. © 2015 Elsevier B.V

Levulinic acid-based bioplasticizers: A facile approach to enhance the thermal and mechanical properties of polyhydroxyalkanoates

Plasticizers are the most used polymer additives world-wide. Nowadays, conventional plasticizers (e.g. phthalates) do not meet the requirements in terms of renewability, biodegradability and cytotoxicity that have become necessary, especially if they are compounded with biopolymers. In this study, novel bioplasticizers are synthesized from levulinic acid via a protecting-group-free three-step process. After FT-IR and NMR characterization of the synthesized molecules, their plasticization effect has been tested with poly(3-hydroxybutyrate) (PHB) as a model semicrystalline biopolyester characterized by a narrow processing window, slow re-crystallization and high brittleness, which limit its processability and diffusion. The proposed bioplasticizers show remarkable miscibility with PHB and low leaching. The bioplasticizers also show a remarkable plasticization effect in terms of reducing the glass transition and melting temperatures (17 °C and 8 °C, respectively), which are comparable with the performance of the best commercially available green plasticizers. Furthermore, flexibility and crystallinity are positively affected, leading to an overall reduction in the typical brittleness of PHB. The observed effects result in an expansion of the temperature range in which PHB can be processed without thermal degradation. Moreover, the incorporation of the levulinic acid-based additives does not significantly affect the typical biodegradability and biocompatibility of PHB, showing their promising features as bioplasticizers for both environmental and biomedical applications

Bio-based lacquers from industrially processed tomato pomace for sustainable metal food packaging

Bio-based lacquers prepared from an underutilized tomato processing residue such as pomace have been investigated as sustainable alternatives to bisphenol A (BPA)-based coatings for metal food packaging. The fabrication methodology consisted of a two-step process: spray-coating of a paste of the lipid fraction of tomato pomace with a mixture ethanol:H2O (3:1, v:v) on common metal substrates, used for food canning, such as aluminum (Al), chromium-coated tin-free steel (TFS), and electrochemically tin-plated steel (ETP), followed by the self melt-polycondensation of such lipid fraction. The polymerization reaction was conducted at 200 degrees C for different times (10, 20, 30, 40, 50, and 60 min) and was monitored by specular infrared spectroscopy, resulting in maximum degrees of esterification of-92% for Al and-85% for TFS and ETP substrates. The anticorrosion performance of the coatings was studied by electrochemical impedance spectroscopy at different immersion times (time intervals of 2-5 h during an overall stability test up to 170 h) in an aqueous solution of 1 wt% NaCl. The degree of polymerization and the physical properties of the coatings showed a strong dependence on the metal substrate used. In general, the best results were found for tomato pomace-based lacquers applied on aluminum, achieving higher mechanical strength (critical load of 1739 +/- 198 mN for Al, 1078 +/- 31 mN for ETP, and 852 +/- 206 mN for TFS), hydrophobicity (water contact angle-95 degrees for Al,-91 degrees for ETP, and-88 degrees for TFS), and improved anticorrosion performance (coating resistance of 0.7 M omega cm2 after 170 h of immersion for Al, 0.7 M omega cm2 after 70 h of immersion for TFS, and negligible coating resistance for ETP). In view of the technical innovation proposed in the present paper, the estimation of the environmental sustainability of the process has been considered relevant to fit the circular economy target. For this purpose, a life cycle analysis (LCA) was applied to the overall process, revealing multiple advantages for both the environment and human health

Antimicrobial, antioxidant, and waterproof RTV silicone-ethyl cellulose composites containing clove essential oil

Ethyl cellulose (EC)/polydimethylsiloxane (PDMS) composite films were prepared at various concentrations of PDMS in the films (0, 5, 10, 15, and 20 wt.%). Morphological and chemical analysis by EDX-SEM and ATR-FTIR showed that EC-rich matrices and PDMS-rich particles were formed, with the two polymers interacting through H\u2013bonds. The number and diameter of particles in the composite depended on the PDMS content and allowed a fine tuning of several properties such as opacity, hydrophobicity, water uptake, and water permeability. Relative low amounts of clove essential oil were also added to the most waterproof composite material (80 wt.% ethyl cellulose and 20 wt.% PDMS). The essential oil increased the flexibility and the antioxidant capacity of the composite. Finally, the antimicrobial properties were tested against common pathogens such as Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The presence of clove essential oil reduced the biofilm formation on the composites

Direct Transformation of Edible Vegetable Waste into Bioplastics

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

Sustainable Electronics: Sustainable Electronics Based on Crop Plant Extracts and Graphene: A “Bioadvantaged” Approach (Adv. Sustainable Syst. 11/2018)

In today's fast‐paced and well‐connected world, consumer electronics are evolving rapidly. As a result, the amount of discarded electronic devices is becoming a major health and environmental concern. The rapid expansion of flexible electronics has the potential to transform consumer electronic devices from rigid phones and tablets to robust wearable devices. This means increased use of plastics in consumer electronics and the potential to generate more persistent plastic waste for the environment. Hence, today, the need for flexible biodegradable electronics is at the forefront of minimizing the mounting pile of global electronic waste. A “bioadvantaged” approach to develop a biodegradable, flexible, and application‐adaptable electronic components based on crop components and graphene is reported. More specifically, by combining zein, a corn‐derived protein, and aleuritic acid, a major monomer of tomato cuticles and sheellac, along with graphene, biocomposite conductors having low electrical resistance (≈10 Ω sq−1) with exceptional mechanical and fatigue resilience are fabricated. Further, a number of high‐performance electronic applications, such as THz electromagnetic shielding, flexible GHz antenna construction, and flexible solar cell electrode, are demonstrated. Excellent performance results are measured from each application comparable to conventional nondegrading counterparts, thus paving the way for the concept of “plant‐e‐tronics” towards sustainability