An investigation on crystallization property, thermodynamics and kinetics of wollastonite glass ceramics

Wollastonite glass ceramics were prepared using the reactive crystallization sintering method by mixing waste glass powders with gehlenite.The crystallization property,thermodynamics,and kinetics of the prepared wollastonite glass ceramics were determined by X-ray diffraction analysis,scanning electron microscopy,energy-dispersive spectroscopy,high-resolution transmission electron microscopy,and differential thermal analysis.Results showed that crystals of wollastonite and alumina could be found in the gehlenite through its reaction with silicon dioxide.The wollastonite crystals showed a lath shape with a certain length-to-diameter ratio.The crystals exhibited excellent bridging and reinforcing effects.In the crystallization process,the aluminum ions in gehlenite diffused into the glass and the silicon ions in the glass diffused into gehlenite.Consequently,the three-dimensional frame structure of gehlenite was partially damaged to form a chain-like wollastonite.The results of crystallization thermodynamics and kinetics indicated that crystallization reaction could occur spontaneously under a low temperature(1173 K),with 20 wt%gehlenite added as the reactive crystallization promoter.The crystallization activation energy was evaluated as 261.99 kJ/mol by using the Kissinger method.The compression strength of the wollastonite glass ceramic samples(7.5 cm×7.5 cm)reached 251 MPa.

Study on Starch Properties of Rice Enriched with Resistant Starch

This study aimed to compare starch properties among rice germplasms with different contents of resistant starch. Rice germplasms with significant differ- ences in resistant starch content were screened by the rice germplasm resource project team in Jiangsu Academy of Agricultural Sciences, to analyze the differences in RVA eigenvalues and starch crystal thermodynamic properties using differential scanning calorimeter （DSC）. The result showed that three rice materials with high contents of resistant starch exhibited low breakdown viscosity and high setback vis- cosity; three rice materials with low contents of resistant starch exhibited high breakdown viscosity and low setback viscosity. Significant differences were observed in RVA eigenvalues and starch crystal thermodynamic properties among rice germplasms with different contents of resistant starch, which provided new indices for breeding functional rice cultivars with high resistant starch content.