The Collagen Fiber Structure And Resistance To Dry Heat

For the first time, the influence of different unhairing methods on the dry heat resistance of collagen fibers is studied. According to physiological statistic data, through comparing the experiment results, the content and materials of man-made sweat are determined. Some man-made sweat is prepared. Some samples including un-tanned cattlehide collagen fibers, different tanned cattlehide collagen fibers, different retanned cattlehide collagen fibers, and fatliquored cattlehide collagen fibers, are prepared and processed in man-made sweat. Preliminary studies on their dry heat shrinkage and thermal degradation behaviors are completed. The mechanism of the changes in thermal behaviors of the samples before and after sweat process is discussed. Results show that soaking in sweat may decrease their dry heat resistance. For difference cattlehide collagen fibers, the decrease degrees are different, which shows that the influencing mechanism of sweat on cattlehide collagen fibers is different.In this paper, the thermal degradation behaviors of some samples including un-tanned cattlehide collagen fibers, chrome tanned cattlehide collagen fibers and glutaraldehyde tanned cattlehide collagen fibers, are also studied by means of TG (Thermo-gravimetric) analysis. Both Flynn-wall-Ozawa and Satava-Sestak methods are employed to process the data got from TG analysis and the thermal degradation activation energies of these samples before and after sweat soaked are worked out. It is also preliminarily studied how sweat affects the samples. The results show that the thermal degradation stability of un-tanned cattlehide collagen fibers and glutaraldehyde tanned leather collagen fibers may be affected slightly by sweat soaking. On the contrary, after being sweat soaked, obvious changes may be found in the case of chrome tanned cattlehide collagen fibers. It is to say that chrome tanned cattlehide collagen fibers may be degraded easily because of sweat soaking. On the basis of the results obtained above, it is found that the mechanism of dry heat shrinkage behaviors is different from that of thermal degradation behaviors. The changes of the former may be the change in aggregation structure, while the change of the latter is the breakage in the whole molecule chains.The influences of sweat process on the physical performance of the crust leather and goat wet-blue leather are also studied, which may facilitate the prediction of the changes in physical performance of leathers after a long period of being worn.The differences in dry heat resistance and water vapor permeability of both cattlehide collagen fibers and crust leather are also studied, with the influencing of ultrasound at different workshop section taken into consideration. Little influence is found of ultrasound on the dry heat resistance of the samples studied here. Different temperature and time of heat treatment (heat preservation and being heated) is carried out, which may provide a proof for further researches on the dry heat shrinkage process of cattlehide collagen fibers. The changes of cattlehide collagen fibers when the shrinkage takes place are studied as well by DSC. The results show that the melting process of cattlehide collagen fibers is a denaturation process. By FT-IR and X-ray (with change temperature accessory), the dry heat shrinkage process of untanned cattlehide collagen fibers is traced in real-time dynamic state. The results show that, when the temperature rises to phase transition temperature, obvious changes may be found in position, height and shape of absorption peaks. The basis of phase transition mechanism of cattlehide collagen fibers may be obtained by combing the two experiment methods mentioned above.