Search

Chitosan microspheres were prepared by ion induction and chemical cross-linking using water as the medium. Natural rubber/chitosan microsphere blends were then prepared by blending the chitosan microsphere suspension with natural rubber latex. An infrared spectrometer, particle size analyser, scanning electron microscope, surface contact angle analyser, thermogravimetric analyser, and differential scanning calorimeter were employed for structure and property characterisation. The results showed that the average particle diameter and the polydispersity index of chitosan microspheres were 323.8 nm and 0.283, respectively. The thermal stability and mechanical properties of natural rubber/chitosan blends were enhanced by introducing chitosan microspheres into natural rubber latex. The water contact angle was significantly decreased, from 94.64° to 55.47°, indicating improved hydrophilic properties for the natural rubber/chitosan film. The natural rubber/chitosan blends showed excellent antibacterial properties when the chitosan microsphere content was >4.00% w/w. [ABSTRACT FROM AUTHOR]

The thermal degradation of chitosan and chitosan-cupric ion compounds in air was studied using thermogravimetric and differential thermal analyses in the temperature range 30-600 °C. The impact of cupric ion on the thermo-oxidative degradation of chitosan was investigated. Fourier transform infrared and X-ray diffraction analyses were utilized to determine the microstructure of the chitosan-cupric ion compounds. Kinetic parameters such as activation energy, pre-exponential factor, Gibbs energy, and enthalpy and entropy of activation were determined using the Coats-Redfern equation. The results show that the thermo-oxidative degradation of chitosan and chitosan-cupric ion compounds is a two-stage reaction. The impact of cupric ion on the thermo-oxidative degradation of chitosan is significant, and all thermodynamic parameters indicate that the thermo-oxidative degradation of chitosan and chitosan-cupric ion compounds is a non-spontaneous process and proceeds via a mechanism involving nucleation and growth, with an Avrami-Erofeev function ( A4) with the integral form [−ln(1 − α)]4. Copyright © 2010 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: The thermal degradation of quaternized chitosan–cupric ion compounds in nitrogen was studied by thermogravimetry analysis (TG) and differential thermal analysis (DTA). The effect of cupric ions on the thermal degradation behaviors of quaternized chitosan was discussed. Fourier transform-infrared (FTIR) and X-ray diffraction (XRD) were utilized to determine the micro-structure of quaternized chitosan–cupric ion compounds. The results of FTIR and XRD show that there are coordinating bonds between quaternized chitosan and cupric ions. Thermal analysis indicates that the thermal degradation of quaternary chitosan–cupric ion compounds is a two-stage reaction, in which there are the decomposition of N–C2 bond on the side-chain of quaternized chitosan and the cleavage of glycosidic linkages of chitosan. The two reactions are exothermic. The impact of cupric ion on the thermal degradation of quaternized chitosan is significant, and the temperature and activation energy of the degradation are related to the weight fraction of the cupric ion. [Copyright &y& Elsevier]

The article presents a study which investigates the effect of cupric ion on the thermal degradation of chitosan in nitrogen. It states the use of thermogravimetry analysis to examine the thermal degradation behaviors of chitosan, while the fourier transform-infrared (FTIR) and X-ray diffractogram (XRD) analysis to determine the structure of chitosan-cupric ion compounds. Result shows that the thermal degradation of chitosan varies in two-stages such as deacetylation and thermal destruction.

Abstract: The thermal degradation of chitosan–cobalt complex at different heating rates in nitrogen was studied by thermogravimetric analysis (TGA) in the temperature range 30–800°C. Fourier transform-infrared (FTIR) and X-ray diffractogram (XRD) analyses were utilized to determine the micro-structure of chitosan–cobalt complex. The results indicate that the thermal degradation of chitosan–cobalt complex in nitrogen is a two-step reaction, characteristic temperatures and the maximum reaction rate of thermal degradation increase with the increment of heating rate. The kinetic parameters were determined by using Friedman and Flynn–Wall–Ozawa methods. Coats–Redfern method was used to discuss the probable degradation mechanism. The results show that activation energy of the complex resulting from two kinetic methods has similar variable tendency, and the solid-state decomposition in the first degradation stage, which is non-spontaneous, goes to a mechanism involving nucleation and growth, Avrami–Erofeev function (A 4) with integral form [−ln(1− α)]4. [Copyright &y& Elsevier]