In the current study, mechanical, thermal, thermo‐mechanical, and shape memory behavior of polyurethane/carbon nanotube nanocomposites were investigated, and also a modified Halpin‐Tsai equation was used for the first time to model shape recovery stress of these smart composites. Results showed that strength enhanced with the addition of MWCNTs and improved to a maximum value of 130% for PU‐1wt%CNTs. SEM micrographs were also used to prove the presence of agglomerates at higher CNT contents. By investigating thermogravimetry curves, it was concluded that the incorporation of carbon nanotubes transferred thermal degradation to a higher temperature. Storage modulus improved for nanocomposite samples which showed the reinforcing effect of CNTs on polyurethane. Memory behavior showed that recovery stress was increased for PU‐CNTs samples to a maximum value of 100% and not any harmful effect on shape recoveries observed. Finally, modified Halpin‐Tsai equation was obtained with the correction factor of K = exp(−1.79‐152Vf).
In this paper, the effect of the crystalline microstructures of polyvinylidene fluoride (PVDF), as cathode binder, on mechanical and electrochemical properties of the cathode, and on the cell performance is investigated. The crystalline phases of the PVDF films prepared at different temperatures are determined by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) and also mechanical strength of PVDF films evaluated by a tensile test. The cathodes were prepared at altered temperatures to achieve different PVDF phases. The effect of various crystalline phases on the cathode performance was studied. The obtained cathodes were analyzed by scanning electron microscope (SEM), contact angle measurement, and adhesion test. The electrochemical performance of the cathodes was evaluated by charge-discharge cycling test and AC impedance spectroscopy. Mechanical tests results showed that the cathode which is prepared at 60 °C has the best adhesion and mechanical stability. In addition, the charge-discharge cycling studies showed that this cathode has the highest capacity efficiency. AC impedance spectroscopy illustrated that this electrode has the lowest charge transfer resistance and SEI resistance.
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