In this study, shape memory is thermally induced in a series of graphene oxide (GO) filled poly(lactic acid)/thermoplastic polyurethane (PLA/TPU) blends, prepared via melt mixing process, and their shape recovery and shape fixity are measured, and the results are correlated with morphology, dynamic mechanical properties, crystallinity and creep recovery behavior. Morphological analysis by scanning and transmission electron microscopy reveals that the blends are immiscible, and GO platelets are mainly localized in the TPU phase of the blends, which lead to smaller and more elongated TPU droplets with improved interfacial adhesion being responsible for the improved shape recovery performance compared to the unfilled blend. A systematic enhancement found in storage and Young's modulus, tensile strength, creep resistance and creep recovery, and cold crystallinity as a result of GO inclusion are in agreement with the improved shape recovery, shape fixity and overall shape memory performance of the filled systems. The developed PLA/TPU/GO nanocomposites with highly improved mechanical properties can be utilized as a new class of environmentally friendly shape memory materials for a broad range of applications. 相似文献
Journal of Porous Materials - Mesoporous flower-like FeOOH nanostructure was synthesized via hydrolysis of flower-like iron glycolate in aqueous methylamine solution and ethanol as a solvent with a... 相似文献
This paper proposes frequency reconfigurable antennas using genetic algorithm, suitable for cognitive radio applications. The optimization is applied to find the slot shape and the switches locations in the ground plane of monopole antennas for adjustment of the bandwidth. We introduce a new cost function appropriate for designing antennas for cognitive radio applications. In the first design, the presented antenna can operate in the band of 1.9–3.8 GHz and two sub-bands 1.8–2.78 and 2.78–3.8 GHz using the possible minimum number of switches. In the second design, the proposed antenna works in a wide operating band of 1.85–4 GHz and three different sub-bands 1.72–2.27, 2.27–2.9 and 2.9–3.75 GHz. The proposed antenna with three modes of operation is fabricated and the comparison of the simulated and measured results shows a good agreement.
In this study, nanocomposites based on polyamide 6/carboxylated acrylonitrile butadiene rubber (PA6/XNBR) reinforced by the clay montmorillonite (OMMT) (Cloisite 20A and Cloisite 30B) were prepared by melt mixing. Glycidyl methacrylate-grafted XNBR (XNBR-g-GMA) compatibilizer was used for immiscible blends of PA6/XNBR. The results illustrated that OMMT wanted to be selectively present in the more hydrophilic PA6 phase. Also, by adding the XNBR-g-GMA compatibilizer and increasing OMMT content, tensile strength, rheological and dynamic mechanical properties of the nanocomposites improved. According to transmission electron microscopy (TEM) images, a few layers of OMMT (Cloisite 20A) in the XNBR-g-GMA compatibilizer phase was observed. The results of X-ray diffractometry and TEM analyses demonstrated that the formation of intercalated or exfoliated structures for both types of OMMT nanocomposites. In end of all analysis was found PA6/XNBR reinforced by the Cloisite 30B could be substantially improved by adding XNBR-g-GMA as a compatibilizer when compared to those reinforced by Cloisite 20A. 相似文献
In this study, applying electron beam irradiation method at a relatively low-irradiation dose (20 kGy) under the air atmosphere to prepare injectable polypropylene (PP)/ethylene-octene copolymer (EOC) blends with fine morphology and appropriate performance was investigated. For this purpose, an extrusion PP grade with an EOC grade suitable to improve its impact resistance was melting blended. Gel content and rheological measurements revealed long-chain branching is predominant phenomenon occurring during the irradiation process of EOC. Blend irradiation resulted in changing its melt flow index proper for injection molding. A fine morphology obtained for the unirradiated blend was preserved for the irradiated blend. Moreover, irradiation thermally stabilized the blend morphology. Blends linear viscoelastic behavior discussed by proper rheological models revealed the existence of interfacial interactions and a reduction of the interfacial tension between irradiated blend phases. No significant effect of irradiation on the crystallization characteristics of EOC and the blend was observed. The satisfying impact resistance of the irradiated blend was near to that of the unirradiated blend, although its tensile mechanical properties were less. 相似文献
The present study is conducted to propose a new code for optimizing a multicomponent isotope separation cascade. An efficient code is developed using an enhanced TLBO algorithm with a novel mutation for calculating the optimal parameters. The results indicate that by implementing a new objective function derived from the combination of D function with total interstage flow rates, the optimum tapered cascade is more efficient than the optimal square one. Also, the best feed locations for the separation of the middle components in the square cascade are the middle stages. 相似文献
In this research, zinc sulfide nanoparticles (NPs) with various morphologies such as spherical, flower-like, microspheres decorated with nanoparticles and nanorods were synthesized by two distinct, simple and efficient methods. These approaches include reflux and hydrothermal methods. Zinc nitrate hexahydrate ().6H2O were used as Zn source and thioacetamide (TAA) was used as S source. The effects of TAA to zinc ion mole ratio were investigated on the morphology, particle size, optical and photocatalytic properties of ZnS nanocrystals. In hydrothermal synthesis with increasing Zn2+:TAA mole ratio from 1:1 to 1:2 dendrite-like nanocrystals changed to semi-spherical nanoparticles with average particle size 50–60?nm, with different effect as photocatalysts. But any change at morphology were didn’t observed with changing Zn2+:TAA mole ratio from 1:1 to 1:30 in the reflux method. In the reflux method with increasing in Zn2+:TAA mole ratio, dispersed semi-sphere nanoparticles were observed. The synthesized nanocrystals were characterized by infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive x-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. XRD analysis and FESEM images show that the size of synthesized ZnS NPs is in the range of 15–25?nm. UV–vis spectra showed that by increasing the amount of sulfur source and increasing the reaction time, shifted towards lower wavelengths, and the band gap was in the range of ~ 3.9–4.8?eV for all of the samples. Also, photoluminescence (PL) analysis showed by increasing particle size and degree of agglomeration, emission intensity () decreased. The photocatalytic activity of the as-prepared samples has been compared for the photocatalyst degradation of reactive blue 21. The sample with low Pl intensity has higher photocatalyst efficiency. 相似文献
The density of 11 refrigerants (hydrochlorofluorocarbon (HCFCs) and hydrofluorocarbon (HFCs)) in the extended ranges of temperature and pressure has been calculated using Goharshadi–Morsali–Abbaspour equation of state (GMA EoS) and the results have been shown as the three-dimensional surfaces of density–temperature–pressure. A wide comparison with experimental data was made. The accuracy of the equation of state in the prediction of density was determined by statistical parameters. The results show that the GMA EoS can reproduce the experimental PVT data of HCFCs and HFCs within experimental errors throughout the liquid phase. The thermodynamic properties such as isobaric expansion coefficient, isothermal compressibility, and vapor–liquid equilibrium (VLE) prediction for these HCFC and HFC refrigerants have been performed using GMA EoS. GMA EoS can predict the characteristic feature of pressure behavior of isobaric expansion and isothermal compressibility coefficients. 相似文献