Differential Calanning Calorimetry Case Study

Differential Scanning Calorimetry (DSC) was carried out to investigate the thermodynamic properties of CXB, different carriers, PMs and SD preparations. Their thermograms are represented in Figures (9-14).
The thermogram of CXB in Figure (9) was characterized by single, sharp endothermic peak at 165±0.56°C which represents the melting point of CXB. Some researchers reported that CXB melting point ranging from 160.79–164.64°C (127), and Paradkar A. et al. (2002) reported that sharp endotherm corresponding to its melting point at 163.3°C (128). The thermal behavior of CXB, soluplus, corresponding PM and their SDs at three different ratios were evaluated by DSC in Figure (10). The thermogram for Soluplus showed broad endothermic peak at 71.7°C which could be related to water evaporation, as indicated by TGA where mass change was observed around 100°C (refer to appendix). Other researchers related this peak to glass transition temperature of soluplus. This result was confirmed in previous study, performed by Mendiratta C. et al. (2001) (129). The PM between CXB and soluplus (soluplus:CXB 7:3)
Chitosan (11 KDa) showed a wide endothermic peak over wide range of temperature from 90.6°C to 146.7°C which can be attributed to water evaporation because polysaccharides are hydrophilic polymers that have a strong affinity for water. This result matched with the result of Ujang Z. et al. (2011) (133). And similar to all, the PM between CXB and 11 KDa chitosan (11 KDa chitosan:CXB 7:3) showed both the melting point of the CXB and the broad endothermic peak of chitosan suggesting that CXB present in crystal form. On contrast to other SDs, 11 KDa chitosan based SD with different ratios showed that melting point peak of CXB still present thus all SD remained crystalline. This result will be confirmed by SEM results in next section