Millenniums‐old natural dye indigo ‐ a “new” ambipolar organic semiconductor. Indigo shows balanced electron and hole mobilities of 1 × 10−2 cm2 V−1 s−1 and good stability against degradation in air. ...Inverters with gains of 105 in the first and 110 in the third quadrant are demonstrated. Fabricated entirely from natural and biodegradable compounds, these devices show the large potential of such materials for green organic electronics.
Biocompatible‐ingestible electronic circuits and capsules for medical diagnosis and monitoring are currently based on traditional silicon technology. Organic electronics has huge potential for ...developing biodegradable, biocompatible, bioresorbable, or even metabolizable products. An ideal pathway for such electronic devices involves fabrication with materials from nature, or materials found in common commodity products. Transistors with an operational voltage as low as 4–5 V, a source drain current of up to 0.5 μA and an on‐off ratio of 3–5 orders of magnitude have been fabricated with such materials. This work comprises steps towards environmentally safe devices in low‐cost, large volume, disposable or throwaway electronic applications, such as in food packaging, plastic bags, and disposable dishware. In addition, there is significant potential to use such electronic items in biomedical implants.
Field‐effect transistors fabricated on biodegradable and biocompatible substrates (Ecoflex, hard gelatine, caramelized glucose) from natural or nature‐inspired organic dielectrics and semiconductors materials may form the basis of green‐electronics.
Robust organic thin-film transistors (OTFTs) with high temperature stability allow device integration with mass production methods like thermoforming and injection molding, and enable operation in ...extreme environment applications. Herein we elaborate a series of materials to make suitable gate dielectric and active semiconductor layers for high temperature stable OTFTs. We employ an anodized aluminum oxide layer passivated with cross-linked low-density polyethylene (LD-PE) to form a temperature-stable gate capacitor. As the semiconductor, we use quinacridone, an industrial organic colorant pigment produced on a mass scale. Evaporated MoOx/Ag source and drain electrodes complete the devices. Here we evaluate the performance of the OTFTs heating them in air from 100 °C in 25 °C increments up to 225 °C, holding each temperature for a period of 30 minutes. We find large differences in stability between quinacridone and its dimethylated derivative, with the former showing the best performance with only a factor of 2 decline in mobility after heating at 225 °C, and unaffected on/off ratio and threshold voltage. The approach presented here shows how industriallys calable fabrication of thermally robust OTFTs can be rationalized.
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•Quinacridone pigments as an active component in organic thin film transistors.•Operational air-stability, remarkable temperature resistance and high charge carrier mobility.•Thermal stability up to 225 °C in air without significant degradation.•Quinacridone thin film transistors are candidates for thermoforming and injection molding applications.
In the present paper the effect of the diatomite, also known as diatomaceous earth and kiesel guhr (KG), content on mechanical, thermo-mechanical, melt-flow and thermal performance of thermoplastic ...polyurethane-based composites was investigated. Composites were fabricated by melt blending method with 10, 20, 30 and 40% filling ratios of KG. and injection molded test samples were characterized using tensile, hardness, dynamic mechanical analysis (DMA), melt flow index (MFI), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) analysis. According to test results, KG inclusions effect mechanical, thermal and morphological properties of composites positively up to 30% KG content. Further addition of KG caused remarkable reductions in related properties. Tensile strength of unfilled TPU exhibited increasing trend and elongation showed no obvious difference after KG loadings. TPU/KG composites yield relatively higher MFI values with respect to unfilled TPU. Glass transition temperature of TPU shifted to 6 points higher value by the help of KG incorporation. TGA findings revealed that KG additions caused improvement for thermal stability of TPU. Homogeneous dispersion of KG particles for their lower content, whereas agglomorate formations for higher loading level of KG were confirmed by SEM micrographs. TPU composite containing 10% KG showed the highest results among samples.
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•Diatomite additions yield positive impact on mechanical and thermal behaviors of polyurethane elastomer.•Thermal stability of TPU was enhanced by inclusion of diatomaceous earth.•Composites exhibited higher MFI parameter compared to TPU which was attributed to porous structure of diatomite.•Homogeneous dispersion of diatomite particles into TPU matrix at lower filling ratios was confirmed by SEM analysis.
Rich in protein, carbohydrates, and lignocellulosic, black cumin is a plant that is used in the treatment of many diseases and has antioxidant and anti-tumor properties. Apart from its use in ...medicine, black cumin is used as a filler in the production of new and eco-friendly eco-composites to reduce the environmental pollution caused by petroleum-based classical polymer composite materials. In this study, bio-based thermoplastic polyurethane (TPU) polymer was used as a matrix and black cumin unmodified and modified with 3 different functionalized group silanes, was added as a filler and mixed in a twin-screw extruder, and biocomposite materials in the form of dog-bones were produced by injection molding. Black cumin powders were analyzed by Fourier-transform infrared-attenuated total reflection (FTIR/ATR), field effect scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA), while the mechanical, tribological, morphological, thermal, thermo-mechanical, melt flow index, and biological properties of the produced biocomposites were characterized. According to the results obtained, it was seen that surface treatment of the black cumin with silane both improved the biodegradability and other properties of eco-composites. Among thermoplastic polyurethane-based eco-composites, surface modification of black cumin with 3-aminopropyltriethoxysilane had the lowest water absorption capacity of 8% and also the highest abrasion resistance and an improvement of 88.5%. It was observed that the eco-composite containing octyldecyl-modified black cumin had the lowest MFI value of 26, the best biodegradability among the surface-modified eco-composites, the tensile strength of 14.5 MPa, and the highest value compared to other eco-composites. Epoxy-silane modifier yields optimum results in terms of thermal and thermo-mechanical analysis.
Olive pulp, which is formed 80% in the olive oil extraction process, attracts the attention of researchers with the zero waste project in Turkey. Our study aims to prove that olive pulp is not only a ...waste and can be used as a resource when used correctly as a filler in composite materials to provide not only durable but also shorter biodegradation times for polymer-based composite materials. The surface modification process with 3 different silanes containing epoxy, vinyl, and amino groups was applied to the surface of olive pulp (OP) to solve the problem of surface incompatibility with eco-grade thermoplastic polyurethane (TPU) matrix. The oil portion of OP was removed before silane treatments. Surface functions and thermal properties of both modified and unmodified OP powder samples were evaluated by FTIR, SEM, and TGA techniques, respectively. TPU/OP composites were fabricated using melt-compounding process, and mechanical, thermomechanical, thermal, melt flow, wear, biodegradation, and morphological properties of composites were reported. According to test results, TPU/VS-OP (vinyl silanized olive pulp) composite showed the highest hardness and wear resistance values among all composites. Additionally, silane modifications led to remarkable improvements for mechanical, thermal, thermomechanical, and melt flow properties of composites thanks to the enhancement of compatibility and interface adhesion between OP and TPU phases. It seems that VS-OP containing composite sample displayed the highest results in most of the examined results. It has been shown that the addition of unmodified and modified OP filler to TPU caused to level of the biodegradation of pure TPU, and as a result, environmentally friendly composites have been produced.
Thermoplastic polyurethane (TPU) composites containing carbon nanotube (CNT) with the loading ratios from 0.5wt% to 2 wt% were prepared using melt-compounding process. Surfaces of the CNT particles ...were treated with sulfuric acid/nitric acid to purify CNT and to achieve compatible surface characteristics between TPU matrix and CNT. Mechanical, thermal, flame retardant, melt flow, and morphological properties of TPU/CNT composites were investigated. Addition of CNT to TPU matrix causes in a prominent increase in tensile strength, percentage of elongation at break, and tensile modulus values of TPU. The mechanical properties are improved for lower modified CNT loadings. CNT inclusions also improve the thermal stability of pristine TPU. Addition of CNT into TPU matrix causes increase in melting and decomposition temperatures of TPU and decrease in glass transition temperature. The flammability parameters of TPU also shift to higher values after CNT loadings to matrix. Modified CNT additions at higher concentrations exhibit better fire performance. Additions of modified CNT and pristine CNT show different trends in the case of melt flow rate values. Modified CNTs disperse more homogeneously relative to pristine ones into TPU matrix which is due to improvement in interfacial interactions between CNT and TPU.
Thermoplastic polyurethane (TPU) composites filled with fullerene in the range from 0.5 wt% to 2 wt% were fabricated using melt-compounding. Fullerene addition levels up to nearly twofold increase in ...tensile strength, percent elongation, and modulus of TPU. The mechanical properties are improved as modified C60 content decreases. Fullerene loadings also enhance thermal stability of TPU. Glass transition temperature decreases by the inclusion of C60 into TPU matrix. Composites exhibited the improvement for storage modulus and vibration-damping behavior. The UL-94 rating and limiting oxygen index value of TPU are also extended to higher values after C60 loadings. Adjuvant effect is observed on fire performance in which pristine C60 inclusions and higher concentrations of C60 exhibit better fire performance. Additions of C60 give identical melt flow index values with that of TPU. Modified C60 particles disperse more homogeneously than pristine ones into TPU matrix because of the improvement in interfacial interactions between fullerene and polyurethane elastomer.
Diatomite (KG) surface was modified by four different silane coupling agents having amino, epoxy, triamine and octyl functional groups for enhancement of interfacial adhesion between thermoplastic ...polyurethane (TPU) and diatomite. EDX and FTIR spectroscopy techniques were used to evaluate the surface functionalities of modified and neat KG samples. TPU/KG composites were fabricated using melt-compounding process. Mechanical, thermo-mechanical, thermal, melt-flow and morphological properties of composites were reported. Mechanical tests revealed that tensile strength and hardness of TPU extended to higher levels while its flexibility was retained after KG additions. Epoxy-silane modified KG exhibited the highest results in the case of mechanical properties. Glass transition temperature of TPU shifted to higher values by the additions of modified KG. Thermal stability of TPU raised by KG inclusions regardless of modification type. Modified KG containing composites yield lower MFI values with respect to neat KG. Enhancement of interfacial adhesion between TPU and KG phases was confirmed by SEM micrographs of composites in which silane-modified KG surfaces were covered by TPU matrix. Silane modifiers involving amine and epoxy groups led to significant improvement in properties of KG-filled TPU composites. Epoxy-based silane displayed the highest performances thanks to strong interfacial interactions between epoxy functional group and isocyanate segment of TPU.
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•Modification of diatomite surface with four different silane modifiers confer performance of eco-grade TPU composites.•Composite involving epoxy-silane modified diatomite exhibited the best mechanical behavior among all composites.•Thermal degradation temperature of TPU shifted to higher levels by inclusion of diatomite.•Addition of silane modified diatomite caused no obvious change for MFI parameter of TPU.
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