9. (1.5 marks).Name 3 types of precursors for making carbon fibers. * Polyacrylonitrile (PAN). This is a thermoplastic material. * Pitch. This is the lowest quality part of the petroleum products. * Cellulose: Derivative of wood. 10. ( 1mark). Name 2 types of organic fibers. Kevlar from Dupont. Polyethylene fiber (Spectra). 11. (2 marks). Name 4 types of fiber forms. Tow. Yarn Weave Braid Part II: Problems. (Total 20 marks): 1. (5 marks) It is desired to make a polyester using 100 g of ethylene glycol and a stoichiometric amount of maleic acid. After the condensate is removed, how many grams of polyester are obtained? Maleic Acid C O CH CH C OH H O O Ethylene Glycol H CH 2 CH 2 OH O Solution: Mass of maleic acid: 4C + 4 O + 4 H = 116 g/mole Mass of ethylene glycol: 2C +2 O + 6 H = 62 g/mole The condensate consists of 2 water molecules. Mass of the polyester coming from 1 unit of ethylene glycol: 3
116 + 62 – 2(18) = 142 g/mole Mass of polyester corresponding to 100 g of ethylene glycol. M = (100/62) x (142) = 229 g 2 .(5 marks) 100 g of polyester of question 1 is cross linked using styrene. How many grams of styrene are required? Neglect the mass of the peroxide initiator. C O CH CH C O O CH 2 CH 2 O n POLYESTER + + RO CH CH 2 PEROXIDE INITIATOR CROSSLINKING AGENT (STRYRENE) Mass of 1 polyester unit: 6 C + 4 O +6 H = 142 g/mole Mass of styrene molecule: 8 C + 8 H = 104 g/mole In the cross linking reaction, 1 unit of polyester corresponds to 1 unit of styrene. 100 g of polyester would correspond to: (100 g/142)(104) = 73.2 g of styrene.
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- Fall '18
- Dr. S.V. Hoa
- Polymer chemistry, Composite material, Fiberglass, Ethylene glycol