Preparation and physical properties of chitosan-coated calcium sulphate whiskers

To improve the performance of calcium sulphate whiskers (CSWs) in the papermaking industry, a series of chitosan-coated (CS) calcium sulphate whiskers (CS-CSWs) was prepared, with the aim of effectively reducing their solubility in aqueous solutions. The CS-CSWs were prepared by immersing CSWs in a chitosan acid solution and then cross-linking with alkaline gel via hydrogen-bonding interaction. The CS-CSWs were characterised in terms of water solubility, zeta potential, contact angle, scanning electron microscopy, thermo gravimetric analysis and X-ray photoelectron spectroscopy (XPS). The results indicated that chitosan had a good effect on the surface modification of CSWs. Under optimal conditions, the water solubility of CS-CSWs decreased by 50 %, and the contact angle increased by 63 %. The XPS measurement indicated that the relative thickness of the chitosan coating was 9.8 nm.