Influence of Ag and/or Sr Dopants on the Mechanical Properties and In Vitro Degradation of ß-Tricalcium Phosphate-Based Ceramics.

ß-tricalcium phosphate has good biodegradability and biocompatibility; it is widely perceived as a good material for treating bone deficiency. In this research, different contents of strontium (Sr) and silver (Ag) ion-doped ß-tricalcium phosphate powders were prepared using the sol-gel method. After obtaining the best ratio of pore-forming agent and binder, the as-synthesized powders were sintered in a muffle for 5 h at 1000 °C to obtain the samples. Then, these samples were degraded in vitro in simulated body fluids. The samples were tested using a series of characterization methods before and after degradation. Results showed that the amount of Sr and/or Ag doping had an effect on the crystallinity and structural parameters of the samples. After degradation, though the compressive strength of these samples decreased overall, the compressive strength of the undoped samples was higher than that of the doped samples. Notably, apatite-like materials were observed on the surface of the samples. All the results indicate that Sr and/or Ag ß-TCP has good osteogenesis and proper mechanical properties; it will be applied as a prospective biomaterial in the area of bone repair.

Characterization of silane treated and untreated natural cellulosic fibre from corn stalk waste as potential reinforcement in polymer composites.

Natural cellulosic fibres have significant potential as reinforcements to replace synthetic fibres applied in biopolymer composites. A natural cellulosic fibre was extracted from corn stalk waste and then it was treated by silane solution with different concentrations. The influences of silane on chemical, surface morphological and mechanical performances of Corn Stalk Fibre (CSF) as well as impact strength and impact fracture surface morphology of CSF reinforced polymer composites were evaluated in the present work. The chemical results showed that silane treatments remove a certain amount of hemicelluloses and lignin from the CSF surface, and increase the Crystallinity Index (CrI) and Crystalline Size (CrS) of the CSF. The CSF treated with 5 wt.% silane solution (5%STCF) presents a highest tensile strength of 223.33 MPa ± 41.22 MPa and Young's modulus of 18.98 GPa ± 2.43 GPa. The silane treatments can also improve the fibre-matrix interfacial bonding and enhance the impact strength of the polymer composites. The surface morphologies of the untreated and treated natural fibres and the impact fracture surface of the composites were examined by SEM.