Thermal Stability and Degradation Kinetics of Vegetable-tanned Collagen Fiber with in-situ Precipitated Calcium Carbonate

Abstract

The effects of in-situ precipitated calcium carbonate (CaCO3) onthe thermal stability and decomposition kinetics of vegetabletannedcollagen fiber (VCF) are evaluated by thermogravimetry.The kinetic and mechanism analysis of the decomposition stageuse an integrated procedure involving model-free methods andmaster-plots method. Various methods are employed to calculatethe activation energy of the fibers. It is shown that VCF/CaCO3exhibits better thermal stability than VCF in the range 22-350°C.However, thermogravimetric results also show that the presenceof CaCO3 accelerates the decomposition process at highertemperatures. When the conversion values are below 0.4, themost probable decomposition mechanism for VCF and VCF/CaCO3 is random nucleation and nuclei growth (Avrami,equation A2). Above 0.4, the decomposition mechanisms of VCFand VCF/CaCO3 are most probably described by third (F3) andsecond (F2) order models, respectively. Morphological/elementalanalysis showed calcium dispersed evenly over the VCF/CaCO3.