Leather Permeability Of Polymer Materials And Heat Resistance

From viewpoints of the transporting process and mechanisms, the transporting performances of leathers are studied. Models of both of air permeability and water vapor permeability are founded and the laws of materials transporting are analyzed. The process of water vapor transporting are analyzed and simulated by "Grey System Theory" for the first time, the time-state equations and the multi-factors equations relating to the structure of leathers are deduced to predict the water vapor permeability. The influences of each factor are evaluated by grey correlative analysis as well.Some useful conclusions are being made through the studies of the effects of retanning, fat liquoring, location difference and thermal history on the transporting performance. According to the results of the effects of chrome content used in chrome retanning procedure on transporting performance of leather, a range of chrome content is putting forward to get a higher transporting performance, and the reason of these changes are discussed either. On the basis of studies of the transporting performance of leather, a series of protein finishing agents are synthesized from acrylate modified by gelatin with emulsion polymerization. These finishing agents may provide high water vapor permeability to the finished leathers. The effects of our synthesized finishing agents on the transporting performance are also discussed compared with other commercial synthetic polymeric ones; the results prove that our protein finishing agents poses ideal water vapor permeability.Heat resistance is a very important character when hide and leather materials are being processed and being used. Leather materials can be used after provided with preferable heat resistance. In the paper, differential scanning calorimetry (DSC), differential thermal analysis (DTA), thermal gravimetry (TG), differential thermal gravimetry (DTG), polarized optical microscopy (POM), wide angle X-ray diffraction (WAXD), mass spectrum (MS) are being used to study the changes when hide and leather fiber are heated. The processes of these changes of hide fiber being heated are divided into three procedures. The changes of each procedure are discussed and reasoned.Dry heat resistance of hide and leather fiber are studied by means of thermal platform microscope systematically. Such factors as thermal history, tanning (including chrome content in chrome tanning liquors, different types of chrome tanning agents, and different types of tanning agents), water and fat liquoring that may affect the dry heat resistance of hide andleather fiber are included. Changes and their mechanisms are analyzed and discussed combining with the results of thermal analysis and X-Ray diffraction patterns.Thermal degradation process and mechanisms of cattle hide fiber are studied. The thermal degradation activation energy of untanned hide fiber tanned with sugar reduced chrome tanning agents and hide fiber tanned with glutaraldehyde tanning agents are calculated by means of Ozawa and Satava-Sestak methods. Thermal degradation activation energy of un-tanned hide fiber is between 141.085-143.142KJ/mol, after being chrome tanned, it is increased to 2114.462-242.666KJ/mol; thermal degradation activation energy of glutaraldehyde tanned hide fiber is between 141.704-150.511KJ/mol.