D max 2500 5 x ray diffractometer

The X-ray diffraction (XRD) patterns were recorded on a Rigaku D/MAX 2500 V X-ray diffractometer (Rigaku, Tokyo, Japan) with Cu Kα radiation used for phase detection. The microstructure of the samples was obtained by a Hitachi SU8220 scanning electron microscope (Hitachi Limited, Tokyo, Japan). Fourier transform infrared (FT-IR) spectra were obtained by a Tensor II FT-IR spectrometer (Bruker, Mannheim, Germany) using KBr pellets in the range of 4000–400 cm⁻¹ to investigate the chemical nature of the particles. The pore volume, BET-specific surface area, and BJH pore size of the porous calcium carbonate were determined by N₂ adsorption–desorption measurements using an ASAP 2020 (Micrometrics, Norcross, GA, USA). The X-ray photoelectron spectroscopy (XPS) profiles were recorded on a Thermo Scientific K-Alpha (Thermo Fisher Scientific, Waltham, MA, USA). Thermogravimetric (TG-DTG) analysis was performed on a Thermo Plus EVO2 thermogravimetric analyzer (Rigaku, Japan) under a N₂ atmosphere at 10 °C/min from 30 °C to 800 °C. The PCC/PAA sample saturated with water absorption was cut into cuboid shapes (the length, width, and height were 3 cm, 3 cm, and 2 cm, respectively, and the weight was approximately 18 g), and the compressive test of samples was performed using a universal electronic material testing machine (Instron, Norwood, MA, USA) at a compression rate of 5 mm/min.