Study On Structure And Properties Of Dog Hair And Rabbit Hair

The morphology, mechanical properties and hygroscopic properties of dog hairsand rabbit hairs were investigated in this paper. The experimental subject includingtwo kinds of dogs and two kinds of rabbits which were Chinese rural dog, Germanshepherd, Angora rabbit and hare, respectively. As for dogs, the properties of guardhair, intermediate hair and underhair were explored. While, as for rabbits, only theproperties of guard hair and underhair were tested for rabbit doesn’t have intermediatehair. The diameter, length and density of hairs were measured to illustrate thefundamental characteristics of samples. In order to analysis the difference ofmorphology, scale structure, medulla structure, secondary structure and crystallinitystructure of hair samples were observed. And the mechanical properties weredetermined by the values of bending rigidity, equivalent bending modulus, breakingstrength, extension at break and friction factor. The wetting properties and moistureabsorption of samples were used to identify the hygroscopic properties of hairs. Thechanges of morphology and basic properties during the growth of hairs were studiedthrough comparing the properties of guard hair, intermediate hair and underhair.Several conclusions have been drawn through the foregoing studies:(1) The guard hair scales of two dog hairs were irregular arranged and the edgeof the scales were sawtooth pattern. While the scales of intermediate hair andunderhair were arrangement regularly and the scales pattern at the tip of those hairs ofChinese rural dog and German shepherd were circular arc and sharp shape,respectively. The scale pattern of guard hair and underhair of hare were long obliqueshape. The guard hair scale and underhair scale of Angora rabbit were wave arrangedirregular arranged, respectively. The scales of underhair were the most closelyarranged in three kinds of hairs. Furthermore, the medulla of guard hair, intermediatehair and underhair of two dogs were a floccular structure intercalated with holes, aporous structure and a wide lattice structure, respectively. The medulla of guard hair and underhair of two rabbits were one column of medulla structure and multiserialmedulla structure. As for the same kind of animal, guard hair had the largest medullapercentage and underhair had the smallest medulla percentage.(2) The analysis of amide I region implied that there was apparent variety in thesecondary structure of different samples. As for the sample kind of animal, theamount of α-Helix structure increased and the content of β-Turn structure decreasedwith the growth of hairs. Compared with guard hair, intermediate hair had higheramount of the α-Helix structure, the values of Chinese rural dog, German shepherd,Angora rabbit and hare increased112.57%,73.37%,45.56%and15.05%, respectively.On the contrary, the β-Turn structure amount of intermediate hair decreased incomparison with guard hair, the values of Chinese rural dog, German shepherd,Angora rabbit and hare decreased55.50%、44.97%、61.58%and64.81%., respectively.The results indicated that the β-Turn structure may be an intermediate structure whichcan transform to α-Helix structure during the growth of hair.(3) The crystal structure improves with the growth of hairs. As for dog hairs,guard hair had the highest crystallinity while the crystallinity values of underhair werethe lowest. Similarly, as for rabbit hairs, guard hairs had higher values of crystallinitythan underhair. Moreover, there are large difference among the crystal structure ofhair samples.(4) The bending properties of dog hairs is similar to rabbit hairs, and the increaseof the diameter results in the increment of the equivalent bending modulus. However,there are no proportional relation between the diameter and the equivalent bendingmodulus. Moreover, the increase of bending rigidity of fibers bringing about theimprovement of the heat-insulating property of fiber assemblies to a certain degree.(5) As for the same kind of animal, underhair had the largest breaking strengthand the smallest extension at break. Furthermore, the frictional coefficients of theunderhair, either along the scales or against the scales, are the smallest among thethree kinds of hairs. In addition, the felting property which represents the frictionalcoefficients difference between along and against the scales was measured and theintermediate hair performed the best felting property. In contrast to underhair andintermediate hair, guard hair had the lowest values of breaking strength, the smallestfrictional coefficients and the highest values of extension at break.(6) The wetting ability of dog hairs was better than that of rabbit hairs. As for thesame kind of animal, the wetting property of underhair was the best and that of guardhair was the worst. Moreover, underhair had the highest equilibrium moisture regain while that of guard hair is the lowest. Comparing dog hairs, the equilibrium moistureregain of rabbit hairs was higher and close to each other.(7) A relational expression to calculate the dog fur heat transfer coefficient wasestablished based on the length of guard hair, length of intermediate hair, length ofunderhair and the hair density. According to this formula, it can be relatively simple topredict the heat transfer coefficient of fur through the basic properties of fur anddeviation are controlled within5%.