chemistry behind hairs
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1. The document discusses hair, its chemistry, tensile strength, and other factors. It summarizes that hair is composed of keratin protein and has a tensile strength of around 200 MPa. 2. It describes methods of measuring tensile strength using a tensometer and definitions of terms like stress and strain. Measurement results for various materials are shown with human hair having a tensile strength of 200 MPa. 3. The document discusses several hair myths and facts, such as shaving not affecting hair growth, conditioner not being able to repair split ends but improving appearance, and smoking being linked to gray hair. It also covers causes of hair loss like stress, medications, infections and treatments for hair
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chemistry behind hairs
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- 4. I would like to express my sincere gratitude to my chemistry mentor Mr. S.K. PAUL for his vital support, guidance and encouragement without which this project would not have come forth from my side. I would also like to express my heartily gratitude to principal Mrs. LILLY SIDDHARTAN for providing support to finish project on time. I wish to thanks my PARENTS for their undivided support & interest who inspired me & encouraged me to go my own way, without which I would be unable to complete my project. And at last by no means the least I would thank to ALMIGHTY who made all the things possible. 4
- 5. INDEX 5
- 6. AIM :- • investigating oN hAIR ,iTS cHEMISTRY ,tENSILE ,aN oTHER fACTORS. 6
- 7. INTRODUCTION • A hair can be defined as a slender, thread-like outgrowth from a follicle in the skin of mammals • Hair is composed of structural protein αkeratin • This protein exists in α-helical form and is rich in cystine , oxidized form of amino acid cysteine 7
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- 10. tensile strength • • • • • The point of failure i.e the time at which it breaks on providing stress, is of much interest and is typically called its "Ultimate Strength" or UTS on the chart. Typically, the testing involves taking a small sample with a fixed cross-section area, and then pulling it with a tensometer, gradually increasing force until the sample breaks. When testing metals, indentation hardness correlates linearly with tensile strength. This important relation permits economically important nondestructive testing of bulk metal deliveries with lightweight, even portable equipment, such as hand-held Rockwell hardness testers. Stress is force acting unit cross section area thus, Tensile stress = F/A (unit-pascal). Strain is extension per unit length thus, Tensile strain = e/l. 10
- 11. Obserevation Sr. No. Material tensile strength 1 Human Hair 200 2 Human Skin 20 3 Ordinary steel 400 4 Nylon Thread 75 5 Spider web (dragline) 1200 6 Carbon nanotube 62000 7 Carbon Fiber 6370 Sufficient tensile strength helps in maintaining toughness of hair, thereby a good hair breakage index which enables it long lasting. 11
- 12. Effect of shaving and cutting hair Cutting with scissors, shaving has no effect on hair growth. ( The myth was exploded by Dr. Mildred Trotter* at the Washington University School of Medicine ) Reasons for the Disbelief 1. The shortness of the shaft of a shaved hair allows changes in its length to be noticed more easily than noticing increase in length of beard. 2. Apparent coarseness is caused by the short, shaved hairs being held more erect by the follicles clasped firmly around them. * Under Dr. Trotter¹s observation, three girls shaved their legs from knee to ankle, twice a week for a period of eight months. At the end of this time, microscopic examination revealed that there was absolutely no increase in the diameter or color of the hairs before or after the shaving period. 12
- 13. Excessive washing of hair causes hair loss/dryness Frequency of washing doesn’t harm hair. Although the recommendation is three times a week. Conditioner helps repair split ends Conditioner can’t "repair" damaged hair. What it can do is smooth down the cuticle and make hair seem in better condition. A good conditioner can also prevent damage from occurring in the first place. 13
- 14. Sleeping with wet hair causes scalp fungus Scalp or fungal diseases can’t be caught from sleeping with wet scalps. Scalp infections require prior involvement with infected sources such as humans, tainted hair care tools or animals. Scalp fungus (tinea capitis) mainly affects children, whose immune systems make them more susceptible to skin infections. Smoking causes gray hair According to J. G. Mosley of the Leigh Infirmary in Lancashire, England in an article in Science News (January 11, 1997) smokers are four times more likely to have gray hair than non-smokers. Even worse, smoking has been conclusively linked to accelerated hair loss. 14
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- 16. 1.The cause of the most common type of hair loss is physical or emotional stress. 2.According to the mayo clinic. Doctors refer to this type of hair loss as telogen effluvium. It occurs when stress causes a large amount of growing hairs to settle into a resting phase. Within a few months, the hairs suddenly seem to appear everywhere during hair washing, combing or brushing. The hair will grow back, but not until the stressor has been resolved. 3.Infection like dissecting cellulitis, fungal infections (such as tinea capitis),folliculitis, secondtemporary or permanent hair loss can be caused by several medications, including those for blood pressure problems, diabetes, heart disease and cholesterolary syphilis also causes hair loss 16
- 17. 1.Minoxidil (rogaine) is a nonprescription medication approved for male pattern baldness and alopecia areata. In a liquid or foam, it is rubbed into the scalp twice a day. However, only 30–40% of patients experience hair growth most frequent side effects are mild scalp irritation, allergic contact dermatitis, and increased facial hair 2. Finasteride (propecia) is used in male-pattern hair loss in a pill form taken on a daily basis. It is not indicated for women and is not recommended in pregnant women. Treatment is effective within six to eight months of treatment. Side effects include decreased sex drive, erectile dysfunction, ejaculatory dysfunction, gynecomastia, and myopathy, hair loss resumes again.. Once treatment is stopped 17
- 18. 3. Immunosuppressants applied to the scalp have been shown to temporarily reverse alopecia areata, though the side effects of some of these drugs make such therapy questionable. 4. Hormonal modulators (oral contraceptives or antiandrogens such as spironolactone and flutamide) can be used for female-pattern hair loss associated with hyperandrogenemia. 18
- 19. How can hair stretch? Before breaking, a hair undergoes changes. For example, by delicately handling a reasonably long hair it can easily be shown that it behaves like a piece of elastic; after extending slightly, it returns to its original length. The use of the extensiometer which progressively stretches a hair at the rate of 1 cm per minute allows precise study of the modifications hair undergoes before it breaks. Thus, for lengthening of up to 5%, hair is elastic. 19
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