Axis ultra dld

The crystalline microstructures of the samples were examined by XRD (X-ray diffraction, Rigaku D/Max-2400 diffractometer, Cu Kα radiation, λ = 0.15406 nm) in the range of 10–80° with a scanning speed of 2° min⁻¹. The applied tube voltage and current were 40 kV and 30 mA, respectively. The element types, valence states and detailed chemical bonding energy were investigated by X-ray photoelectron spectroscopy (XPS, Kratos AXIS Ultra DLD, Al Kα probe beam, the applied photoelectron energy hv = 1486.6 eV), and the nanofiber sample was pressed into a film by a tablet press and evacuated for 1 day before testing. The fitting software of the high-resolution spectra was XPS Peak.
To prepare the FE-SEM (field-emission scanning electron microscopy, S-4800, Hitachi) characterization, the sample is glued to the metal table with conductive glue. In addition, a TEM (transmission electron microscopy, FEI, Tecnai G² F20) with EDX (energy dispersive X-ray) spectroscope was applied to acquire the detailed microstructure and composition. During the sample preparation, the sample was first put into an alcohol solution and ultrasonicated for about 10 min. Next, a dropper was used to draw a small amount of supernatant onto the micro-grid. Finally, the micro-grid with the sample was dried for a few minutes to evaporate alcohol.

The samples were characterized by using a MultiMode 8 AFM (Bruker) equipped with a J scanner. Silicon cantilevers coated with a 30 nm Pt layer with a nominal spring constant of 2.8 N·m⁻¹ and oscillating frequencies of 60–90 kHz (NSC18/ Pt, MikroMasch Co.) were used. Height and adhesion mapping were conducted in PeakForce Quantitative Nano-Mechanics (PF-QNM) mode, in which the maximum force (peak force) applied to the sample by the tip was directly regulated through the peak force setpoint and kept constant throughout the whole scan. In this mode, the peak force amplitude was set at 150 nm, the Z-piezo oscillation frequency at 2.0 kHz, and the scan rate at 1 Hz. Voltage to the tip was applied using the scan parameter “tip bias”. All AFM experiments were conducted under ambient conditions at a room temperature of 18–25 °C and relative humidity of 35–60%. AFM images of the samples were processed using the software Nanoscope Analysis v1.7. For each image, a first-order flatten correction was applied to remove sample inclination. The reduction extent of the GO was characterized by X-ray photoelectron spectroscopy (XPS, AXIS Ultra DLD, Kratos).

ICP-OES measurements were performed on an Agilent ICP-OES 730, while ICP-MS measurements were conducted on an Agilent ICP-MS 7850.
SEM characterization was conducted on a Zeiss sigma 300, or on Zeiss Merlin Compact.
FTIR spectroscopy was conducted on Bruker VERTEX80v or Thermo Fisher Nicolet iS 10 on a range from 400 to 3000 cm⁻¹.
XPS characterization were conducted on a Kratos AXIS Ultra DLD using Alka-ray source (hv= 1486.6 eV). Operation vacuum, voltage, filament current, and pass energy is 1×10⁻⁹ mBar, 15 kV, 10 mA and 30 eV.
HRTEM photographs and EDX mapping and spectra were obtained on a Tecnai G20 20 TWIN UEM.
The specific surface area and pore size distribution of FEP powder were obtained using the Brunauer– Emmett–Teller (BET) approach with BSD-660S.
The TG-DSC analysis was conducted on NETZSCH STA 449 F5 using N₂ atmosphere. The ramp is 10.00 °C per min.
GPC was employed to measure the molecular weight of PP. The experiment was carried on Agilent PL-GPC 220 with PLgel 10um MIXED-B LS 300×7.5 mm tandem column, using 150°C 1,2,4-Trichlorobenzene as the solvent. The flow is 1 mL min⁻¹.
The molecular weight of FEP and PTFE was calculated based on the data provided by Dupont (SSG method), using the formula³⁰ : $Log\overline{Mn}=\frac{2.61-SSG}{0.06}$