Hair Aggregation Structure And Tensile Property

Objective:To identify the impact of humidity on hair aggregation structure and tensile property and the relationship between hair aggregation structure and tensile property.Materials and Methods:(1) The hair samples were collected from 42 healthy volunteers of Chinese Hans aged 21-40 years.No history of special drugs intake or chemical substances contact;no history of exposure to special ultraviolet or other radiation;no history or family history of hair disorders.Those who had their hair chemically treated were excluded.All of the volunteers were informed consent.The hair samples were washed out by distilled water and aired before the tests.(2) The above hair samples were placed in 20℃,45%relative humidity condition for 24 hours to get moisture balance.Under 20℃,45%relative humidity condition,the breaking load and strain at break of the samples were tested separately in dry and wet state by INSTRON-4466 universal testing machine.(3) The hair samples in different elongation states were obtained and cutted powder.The X-ray diffraction patterns of the samples were gained by D/max-2550 PC X-ray diffractometer.The crystallinity of each sample was calculated by peak separation method.(4) The hair samples in different elongation states were obtained. The orientation was measured by SCY-Ⅲspeed of sound fiber orientation measurement.(5) All statistical analysis were performed on statistical software (SPSS 16.0).In general,significance difference was set to P＜0.05.Results:(1) Under dry condition,the breaking strength of hair fiber from 21 males is(1.85±0.28)cN/dtex,the strain at break is(72.245±3.925)%;the breaking strength of hair fiber from 21 females is(1.84±0.30)cN/dtex,the strain at break is(73.304±4.628)%.There is no significant difference of breaking strength and strain of break of hair between male and female in dry state.(2) Under wet condition,the breaking strength of hair fiber from 21 males is(1.46±0.21)cN/dtex,the strain at break is(69.201±3.863)%;the breaking strength of hair fiber from 21 females is(1.45±0.22)cN/dtex,the strain at beak is(70.835±4.856)%.There is no significant difference of breaking strength and strain of break of hair between male and female in wet state.(3) In dry state,the breaking strength of hair fiber from 42 healthy volunteers of Chinese Hans is(1.84±0.28)cN/dtex,the strain at break is (72.774±4.272)%;in wet state,the breaking strength is (1.46±0.21)cN/dtex,the strain at beak is(70.018±4.412)%.There is a significant difference of breaking strength and strain of break of hair between dry and wet state.(4) The crystallinity of the hair from 42 healthy volunteers of Chinese Hans is(28.82±2.60)%,with male(28.58±2.97)%and female(29.05±2.22)%respectively;the orientation is(76.0±1.5)%,with male(76.0±1.5)%and female(76.0±1.5)%respectively.There is no significance difference of hair crystallinity and orientation between male and female.(5) There is a positive relevance of the crystallinity and the breaking strength or strain at break;the sample of high crystallinity has high breaking strength and high strain at break.(6) There is a positive relevance of the orientation and the breaking strength or strain at break;the sample of high orientation has high breaking strength and high strain at break.Conclusion:(1) Hair has a higher breaking strength and a higher strain at break in dry state than in wet state.Humidity can weaken the tensile property of hair.(2) There is a positive relevance of crystallinity,orientation and tensile property of hair.The sample of higher crystallinity and higher orientation also has higher breaking strength and higher strain at break, which shows better tensile property.