Chap16_3pgs - Polqlneffi 16-7 : ( w Thc molecular eightof

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Polqlneffi : 16-7 Thc molecular weight of polymcthyl mcthacrylate (see Table 16-3) is 250,000 g/mol. If all of the polymer chains are the same length, calculate (a) the degree of polymerization and (b) the number of chains in I g of the polymer. Solution: The molecular weight of methyl methacrylate is: MW-5C+2C +8H:100g/mol (a) Degree : 250,000/100 2,500 (b) In I g of the polymer: = 2.408 X lOls chains 16-10 Analysis of a sample of polyacrylonitrile (PAN) (see Table 16-3) shows that there are six lengths of chains, with the following number of chains of each length. Determine (a) the weight average molecular weight and degree of polymerization and (b) the number average molecular weight and degree of polymerization. Solution: Number of 10,000 18,000 17,000 15,000 9,000 4,000 73,000 - Mean Molecular weight of chains (g/mol) xi xiMi weight f, fiM, 0.137 411 30x106 0.044 132 0.247 1482 108 x 106 0.159 954 0.233 2097 153 x 106 0.226 2034 0.205 2460 180 x 106 0.265 3180 0.123 I 845 I 35 x 106 0. 199 2985 0.055 990 72 x 106 0.106 1908 9,285 678 x 106 I1,193 3,000 6,000 12,000 SUilI = The molecular weight of the acrylonitrile monomer MWacryronitr.ite 3 C + I N + 3 H 53 g/mol (a) The weight average molecular weight and degree of polymerization are: MW* 11,193 g/mol DP* 11,193/53 2lI (b) The number average molecular weight and degree of polymerization are: MWn 9,285 g/mol DPn 9285/53 g/mol - 175
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156 The Science and Engineering 0f Materials Instructor's Solutions Manual 16'14
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This note was uploaded on 02/01/2012 for the course MSEG 302 taught by Professor Snively during the Spring '08 term at University of Delaware.

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Chap16_3pgs - Polqlneffi 16-7 : ( w Thc molecular eightof

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