Study On Thermal Degradation Of The Collagen Fiber Dealt With Organic Tanning Agents And Metal Salt

Chrome-free tanning agents have always been one of hot research directions in leather industry.The main chrome-free tanning agents such as F-90,TWT,and TANFOR~TMM T-A(T-A)have been reported in recent years.At present,the research of these tanning agents mainly focuses on its tanning process,tanning performance,environmental protection performance,etc.However,there are few reports on the thermal properties of leathers tanned with these agents.And the study on thermal degradation properties always concentrated on the leather tanned with traditional tanning agents such as chrome powder,aldehyde agents and vegetable tanning agents.Therefore,it`s necessary to systematically study the thermal degradation properties of newly developed green chrome-free tanning agents.In this paper,F-90,TWT and Q16-1 were firstly used to tan delimed and bated raw hides,respectively.And the heat-resistant stability and thermal degradation behaviors of these collagen fibers were studied.The difference in tanning effect of these tanning agents was investigated from the thermodynamic point of view through the thermal stability and thermal degradation process of these tanned collagen fibers.Flynn-Wall-Ozawa method and Satava-Sesták method were used to calculate the thermal degradation activation energy of these collagen fibers by TG/DTG analysis.The results showed that the thermal degradation activation energy of these collagen fibers was increased compared with that of untanned fibers.With increase of the dosage of these tanning agents,the thermal stability of these collagen fibers gradually increased.When the amounts of F-90,TWT and Q16-1 reached to 10%,8%and 10%respectively,the thermal decomposition temperature(Td)of these tanned fibers at high temperature increased significantly.This indicated that the amount of cross-linking for tanning reaction reached to a summit under this dosage.And the thermal degradation mechanism of collagen fibers tanned by the three tanning agents were G(?)=[-ln(1-?)]~4.The activation energy of collagen fibers tanned with F-90,TWT and Q16-1 were 236.965~284.426 KJ/mol,147.603~250.243KJ/mol and 143.55~1227.953 KJ/mol.The collagen fibers were pretanned with a fixed amount of F-90,TWT and Q16-1,and then retanned with different amounts of chrome powder and T-A respectively.The thermal degradation behaviors of the retanned collagen fibers were studied systematically to obtain the corresponding activation energy.The effects of chrome powder and T-A on thermal degradation process of the pretanned fibers were analyzed.The compatibility and synergistic effects of chrome powder/T-A and three chrome-free tanning agents were studied.The results showed that thermal stability of the collagen fibers retanned with chrome powder/T-A went up gradually with increase of the amount of both tanning agents.The thermal stability of fibers retanned by chrome powder was better than that of the fibers retanned by T-A.And the activation energy decreased gradually with increase of the dosage of chrome powder/T-A,while the range of the activation energy gradually shrank otherwise.When the amounts of chrome powder and T-A were 3%and 5%respectively,the Td of collagen fibers pretanned with F-90 tended to be stable and reached a maximum value.And the thermal degradation activation energy were 142.915~175.104 KJ/mol and 150.095~228.111 KJ/mol respectively.The thermal degradation mechanisms of both retanned collagen fibers were G(?)=[-ln(1-?)]~4.When the amounts of chrome powder and T-A were both up to 5%,the Td of collagen fibers pretanned with TWT tended to be stable and reached a maximum value.And the thermal degradation activation energy of collagen fibers were 155.382~207.298 KJ/mol and 164.553~177.287 KJ/mol.The thermal degradation mechanism of both retanned collagen fibers that pre-treated with TWT were G(?)=[-ln(1-?)]~4.When the amounts of chrome powder and T-A were 3%and 5%respectively,the Td of collagen fibers pretanned with Q16-1 tended to be stable and reached a maximum value.And the thermal degradation activation energy of the correspondingcollagenfiberswere155.382~207.298KJ/moland164.553~177.287 KJ/mol.The thermal degradation mechanism of both retanned collagen fibers that pre-treated with Q16-1 were G(?)=[-ln(1-?)]~4.