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Nanosheets of the softest mineral talc are embedded in electrospun poly(vinylidene fluoride) fabric, and substantial piezoelectric response of this nanocomposite fabric is displayed.

Currently, there is considerable research focus on portable, lightweight, shock‐resistant, and inexpensive wearable devices that are ideally powered by harvesting abundant mechanical or vibration energy, making battery or related wiring superfluous. In this study, piezoelectric nanogenerator was electrospun from PANi (polyaniline)/HNT (halloysite nanotube)/PVDF (poly[vinylidene fluoride]) blend nanocomposite. Polymorphism, crystallinity and morphology of the nanogenerator were explored in detail. HNT and PANi acted as a nucleating agent and conductive filler, respectively in PVDF; their synergism helps improve the piezoelectric performance of PVDF. The piezoelectric performance of the nanogenerator patch was studied under various external mechanical stresses, such as pressure, tapping, and impact. A maximum voltage output of approximately 7.2 V was generated by the nanogenerator under impact. The nanogenerator patch attached to human arm exhibited not only excellent piezoelectric response during arm movements, but, also proved to be flexible, highly sensitive and durable. This nanogenerator could possibly be used in wearable piezoelectric energy conversion application for self‐powered devices. POLYM. COMPOS., 40:1663–1675, 2019. © 2018 Society of Plastics Engineers

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ABSTRACT:The curing kinetics of a liquid melamineformaldehyde impregnation resin were analyzed with differential scanning calorimetry, and the conversion-dependent activation energy for melamine-formaldehyde curing was estimated with the isoconversional model-free kinetic approach developed by Vyazovkin. The conversion-dependent activation energy was used to extend the predictive power of a response surface model describing the influence of some processing factors (press time and resin composition) in the manufacturing of particleboards coated with melamine-formaldehyde-impregnated papers. By substituting the factor ''press time'' in an RSM established for a press temperature of 170 C by the factor ''conversion'' which is accessible from thermo-chemical analysis, additional information on temperature was incorporated into the model. Model applicability for additional temperatures was evaluated with 12 validation experiments. Although chemical resistance was difficult to model, cleanability was sufficiently well described by only one factor (conversion). Surface gloss depended on both the conversion and catalyst amount and was predicted by a two-factor interaction model (R 2 ¼ 0.95). This study demonstrates that parameters derived from the isoconversional kinetic analysis of liquid resins not only are theoretical descriptors but also have direct practical relevance in the modeling of product properties derived from these liquid resins when used to supplement technological databases.

Summary: The use of renewable raw materials in the polymer industries is becoming increasingly popular because of environmental concerns and the need to substitute fossil resources. Plant oils with triglyceride backbones can be chemically modified and used to synthesize polymers from renewable resources (biopolymers). In the present study, linseed oil was epoxidized using a chemo‐enzymatic method based on Candida Antarctica lipase B (CALB) as a biocatalyst and the modified linseed oil was cured using maleinated linseed oil and a commercial polyamide resin. The amount of epoxidation achieved depended on the amount of lipase used and was determined by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies. With 20% (weight per weight) catalyst concentration based on the wt % of oil a degree of epoxidation of > 90% was achieved. The cross‐linking reaction of epoxidized linseed oil with the maleinated linseed oil and the polyamide resin was studied using differential scanning calorimetry (DSC). DSC traces showed that an increase in epoxidation degree lead to larger values for the exothermic enthalpy integrals of the curing reactions and hence to a higher reactivity of the linseed oil towards the cross‐linking agents.

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