The reaction of chitosan with cinnamic acid gave the corresponding N-cinnamoyl chitosan (NCC) polymer. The chem-ical structure of the modified polymer was characterized by IR, 1H-NMR and elemental analysis. Thermograv...The reaction of chitosan with cinnamic acid gave the corresponding N-cinnamoyl chitosan (NCC) polymer. The chem-ical structure of the modified polymer was characterized by IR, 1H-NMR and elemental analysis. Thermogravim- etric analysis reveals that the thermal stability of chitosan polymer is greater than NCC polymer. The activation energies of thermal degradation of chitosan and NCC polymers were determined using Arrhenius relationship. Thermal degradation of NCC polymer was studied and the products of degradation were identified by GC-MS technique. It seems that the mechanism of degradation of NCC polymer is characterized by elimination of low-molecular weight radicals. Combination of these radicals and random scission mechanism along the backbone chain are the main source of the degradation products.展开更多
In this paper,Lie point symmetry method is used to obtain the general exact solution of the second order nonlinear ordinary differential equation which goveming heat transfer in rectangular fin with variable thermal c...In this paper,Lie point symmetry method is used to obtain the general exact solution of the second order nonlinear ordinary differential equation which goveming heat transfer in rectangular fin with variable thermal conductivity.Some new forms of thermal conductivity are introduced and the associated exact solution is obtained in each case.The general relation among the fin efficiency,thermal conductivity and thermo-geometric parameter is obtained.展开更多
文摘The reaction of chitosan with cinnamic acid gave the corresponding N-cinnamoyl chitosan (NCC) polymer. The chem-ical structure of the modified polymer was characterized by IR, 1H-NMR and elemental analysis. Thermogravim- etric analysis reveals that the thermal stability of chitosan polymer is greater than NCC polymer. The activation energies of thermal degradation of chitosan and NCC polymers were determined using Arrhenius relationship. Thermal degradation of NCC polymer was studied and the products of degradation were identified by GC-MS technique. It seems that the mechanism of degradation of NCC polymer is characterized by elimination of low-molecular weight radicals. Combination of these radicals and random scission mechanism along the backbone chain are the main source of the degradation products.
文摘In this paper,Lie point symmetry method is used to obtain the general exact solution of the second order nonlinear ordinary differential equation which goveming heat transfer in rectangular fin with variable thermal conductivity.Some new forms of thermal conductivity are introduced and the associated exact solution is obtained in each case.The general relation among the fin efficiency,thermal conductivity and thermo-geometric parameter is obtained.
