TT 105 Questions Quiz 2:
DO NOT LOOK FOR PATTERNS IN THE ANSWERS,
The quiz will probably take you 10-15 minutes,
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.”
ALL of these statements are true
You can take the test Tuesday OR Thursday; if you take it Tuesday then stay home Thursday.
1. Fibers are called by chemical names
trade names (Dacron®) and generic names (polyester).
2. Natural fibers can be protein, cellulosic (cotton
Manufactured fibers can be regenerated cellulose such as rayon.
4. Natural fibers are made by nature (cotton, wool).
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).
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
11. A stress-strain curve is sensitive to temperature and humidity.
12. The slope of a stress-strain curve is called the modulus.
slope in a stress-strain curve means the material is stiff and hard to stretch.
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
16. Tenacity is the stress or strength where a material breaks; a higher tenacity yarn is more crystalline and
bulletproof vest needs high tenacity and low elongation in order to stop the bullet before it enters the body.
swimsuit requires high elongation not strength.
19. Cotton gets stronger when wet, nylon gets weaker when wet, polyester doesn’t change.
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.