In this study, bio-based phase change material (bio-PCM) was successfully encapsulated in ultrafine fibers via coaxial electrospinning technique. Natural soy wax was used as the bio-PCM for thermal storage and Polyurethane (PU) was used as the shell material for encapsulation. The bio-PCM fibers were characterized by environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and X-ray Diffraction (XRD). The results indicate that coaxial electrospinning resulted in a uniform fiber morphology with a core-shell structure, and a homogeneous wax distribution throughout the core of the fibers. Thermal analysis results show that the enthalpy increases with wax content. The fibrous structures exhibited balanced thermal storage and releasing properties for thermo-regulating functions. The thermal properties were unaltered after 100 heating-cooling test cycles, demonstrating that the composite fibers have good thermal stability and reliability.

Encapsulation of bio-based PCM with coaxial electrospun ultrafine fibers

Development and surface improvement of FDM pattern based investment casting of biomedical implants: A state of art review

Complex dielectric, complex electric modulus, and electrical conductivity in Al/(Graphene-PVA)/p-Si (metal-polymer-semiconductor) structures

Thermal and mechanical properties of bio-based PCMs encapsulated with nanofibrous structure

For the investigation of the influence of (PVP: Zn-TeO2) interphase layer on the electrophysical parameters, Al/p-Si structures with/without (PVP: Zn-TeO2) interlayer grown by spin-coating technique and then these factors were studied by I–V and Z–f measurements. First, the Field Emission Scanning Electron Microscopy (FE-SEM), X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDS), and UV–Vis analyses techniques were performed to investigate the morphology, purity determination, and the optical properties of the nanostructures, respectively. Second, I–V measurements and Z–f were performed at ± 3 and 1.5 V (at 100 Hz–1 MHz), respectively. The values of ideality factor (n), barrier height (BH:ΦB), and series resistance (Rs) of them were obtained using various methods such as thermionic emission, Cheung’s and Norde functions and compared. The energy dependence of surface states (Nss) were extracted from the forward bias I–V measurements by assuming the voltage dependence of BH and n. The frequency-dependence profiles of dielectric constant (e′)/loss (e″), and ac electrical conductivity (σac) were extracted from the Z–f measurements. Experimental results show that (PVP: Zn-TeO2) interlayer leads to an increase in the e′, e″, BH, Rsh, and decrease in Nss. Therefore, Al/(PVP: Zn-TeO2)/p-Si structures can be used as an electronic part in nanoscale instead of MS structures.

Electrical and dielectric properties of Al/(PVP: Zn-TeO 2 )/p-Si heterojunction structures using current-voltage (I-V) and impedance-frequency (Z-f) measurements

In this study, Al/Al2O3/p-Si (MIS) type structures were fabricated and then the effects of Al2O3 interlayer on the electrical characteristics have been investigated at room temperature. For this purpose, capacitance/conductance-voltage-frequency (C/G-V-f) measurements were performed in the wide range frequency (1kHz-5 MHz) and voltage (±3 V) to get more reliable and accuracy results on the barrier height (BH) formation at Al/p-Si interface, conduction mechanisms, and main electrical parameters. Experimental results indicate that C and G/ω values are strong function of frequency and voltage particularly in the regions of accumulation and depletion. Calculating from the interception and slope of C−2-V plot, the doping acceptor atoms (NA), BH and depletion layer width (WD) were obtained for each frequency, respectively. Both BH and WD values exponentially increase by frequency increment. Nicollian-Brews method were used to extract voltage dependence profiles of Rs and frequency from C and G data.

Frequency and voltage dependence of barrier height, surface states, and series resistance in Al/Al2O3/p-Si structures in wide range frequency and voltage

Burhanettin İnem

Papers

Frequency and voltage dependence of barrier height, surface states, and series resistance in Al/Al2O3/p-Si structures in wide range frequency and voltage

Conversion of an investment casting sprue wax to a pattern wax by the modification of its properties