EXAM 105 test 2 review 2006

EXAM 105 test 2 review 2006 - 1 TT 105 Questions Quiz 2: 1....

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TT 105 Questions Quiz 2: 1. DO NOT LOOK FOR PATTERNS IN THE ANSWERS, 2. The quiz will probably take you 10-15 minutes, 3. Multiple quizzes will be issued during the quiz, and if one part of the statement is false and another part true, the question must be marked “False.” 4. ALL of these statements are true    5. You can take the test Tuesday OR Thursday; if you take it Tuesday then stay home Thursday. Fibers: 1. Fibers are called by chemical names , trade names (Dacron®) and generic names (polyester). 2. Natural fibers can be protein, cellulosic (cotton ) or mineral. 3 . Manufactured fibers can be regenerated cellulose such as rayon. 4. Natural fibers are made by nature (cotton, wool). 5. Manufactured fibers are made of either natural polymers (rayon) or synthetic polymers (polyester). 6. Fiber properties affect material properties of the fiber. 7. Mechanical properties include the stiffness, comfort and strength of a product. 8. Fiber properties depend on their internal structure (i.e., such as their crystalinity). 9. A stress (load) – strain (elongation) curve measures how a material reacts to tension. 10. In a stress strain curve, stress (grams/denier) is plotted on the vertical axis, strain (% elongation) is plotted on the horizontal axis. 11. A stress-strain curve is sensitive to temperature and humidity. 12. The slope of a stress-strain curve is called the modulus. 13. A steep slope in a stress-strain curve means the material is stiff and hard to stretch. 14. A less steep slope in a stress-strain curve means the material is easy to stretch. 15. The yield point is where the stress-strain curve begins to flatten; beyond the yield point complete recovery is not possible. 16. Tenacity is the stress or strength where a material breaks; a higher tenacity yarn is more crystalline and stronger. 17. A bulletproof vest needs high tenacity and low elongation in order to stop the bullet before it enters the body. 18. A swimsuit requires high elongation not strength. 19. Cotton gets stronger when wet, nylon gets weaker when wet, polyester doesn’t change. 20. A larger diameter fiber has a higher bending stiffness; a round cross-section is harder to bend than a flat cross-section. 21. In terms of a review for product development: a high modulus, high tenacity, small diameter material gives a strong, flexible structure; a high modulus, high tenacity, large diameter material gives a strong, stiff structure; a low modulus, high elongation, large diameter material gives a stretchy, stiff structure. 22. A polymer is a very large molecule consisting of a large number of molecular repeating units. 23. A material such as Kevlar® has a certain softening point, melting point, and a certain moisture regain.
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This note was uploaded on 04/14/2008 for the course TT 105 taught by Professor Michielsen during the Fall '08 term at N.C. State.

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EXAM 105 test 2 review 2006 - 1 TT 105 Questions Quiz 2: 1....

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