Chap 14 Solns-6E

# Chap 14 Solns-6E - CHAPTER 14 POLYMER STRUCTURES PROBLEM...

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CHAPTER 14 POLYMER STRUCTURES PROBLEM SOLUTIONS 14.4 We are asked to compute the number-average degree of polymerization for polypropylene, given that the number-average molecular weight is 1,000,000 g/mol. The mer molecular weight of polypropylene is just m = 3(A C ) + 6(A H ) = (3)(12.01 g/mol) + (6)(1.008 g/mol) = 42.08 g/mol If we let n n represent the number-average degree of polymerization, then from Equation (14.4a) n n = M n m = 10 6 g/mol 42.08 g/mol = 23,700 14.7 (a) From the tabulated data, we are asked to compute M n , the number-average molecular weight. This is carried out below. Molecular wt. Range Mean M i x i x i M i 8,000-20,000 14,000 0.05 700 20,000-32,000 26,000 0.15 3900 32,000-44,000 38,000 0.21 7980 44,000-56,000 50,000 0.28 14,000 56,000-68,000 62,000 0.18 11,160 68,000-80,000 74,000 0.10 7400 80,000-92,000 86,000 0.03 2580 _________________________ 107

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M n = x i M i = 47,720 g/mol (b) From the tabulated data, we are asked to compute M w , the weight- average molecular weight. This determination is performed as follows:
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## This note was uploaded on 08/30/2011 for the course EGN 3365 taught by Professor Staff during the Spring '11 term at University of Florida.

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Chap 14 Solns-6E - CHAPTER 14 POLYMER STRUCTURES PROBLEM...

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