2.7. Wide-angle X-ray diffraction (WAXD) analysis WAXD measurements were conducted with a Ragaku ModelD/max-2B X-ray diffractometer (Japan) with a Cu/k radiation(40 kV, 20 mA), and the experimental data were recorded in the range of 3–60◦at a scanning rate of 2◦min−1.
2.8. Thermal analysis DSC analysis was carried out with a TA Q2000 differential scanning calorimeter (TA Instruments) at a scanning rate of 20◦C min−1 under nitrogen atmosphere (50 mL min−1). The samples were firstheated to 180◦C and maintained for 5 min to eliminate thermalhistories. After that, they were cooled to 0◦C and held for 10 min.Finally, the samples were reheated again to 180◦C. Both the cooling and heating scans were recorded for analysis.TGA was performed on Perkin-Elmer TGA-7. Samples were heated from 50◦C to 600◦C at a rate of 20◦C min−1 under nitrogen atmosphere.