; Zhang, Xin
; Lu, Cuiyun
; Qi, Chenze] Shaoxing Univ, Inst Appl Chem, Shaoxing 312000, Peoples R China
; [Wang, Baoyi] Chinese Acad Sci, Inst High Energy Phys, Beijing, Peoples R China
Nanometer sized (mean size: 433.9 nm) pearl shell particles (SP) were prepared with a ball mill. Thermal analysis and Fourier transform infrared (FTIR) results proved that the SP contained mainly CaCO(3) (about 95%) and a small organic phase (about 5%). Novel biodegradable composites based upon chitosan (CS) and SPs were prepared using an in situ precipitation method. The organic components of SP are highly compatible with both CS and glutaraldehyde (GA). The strength and modulus of CS gel rods, prepared by coagulation of a CS/SP/GA solution in NaOH, in both the dry and wet state, were improved remarkably with addition of appropriate amounts of SP together with GA. For example, with a composition of 3% SP and 0.3% GA added, the strength and modulus were 42.9 MPa and 1.41 GPa, increasing 75 and 464% compared with CS alone, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results showed that GA acts as not only a crosslinking agent for CS, but also a compatibilizer for CS and SP. It was found that the modified rods have smaller free volume size but nearly the same free volume fraction as pure CS rods. The good interfacial adhesion and more compact microstructure can sensitively reflect the changes in the free volume of the composites.