SolutionsHW9

# SolutionsHW9 - HW 9 Problem 14.5 a To Find(a The...

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HW 9 Problem 14.5 a. To Find: (a) The number-average molecular weight (b) The weight-average molecular weight (c) The degree of polymerization for the given polypropylene material b. Given: Molecular Weight Range (g/mol) x i w i 8,000–16,000 0.05 0.02 16,000–24,000 0.16 0.10 24,000–32,000 0.24 0.20 32,000–40,000 0.28 0.30 40,000–48,000 0.20 0.27 48,000–56,000 0.07 0.11 c. Assumptions: The given data is accurate; the material (polypropylene) is pure. d. Solution: (a) Number-average molecular weight: Molecular wt. Range Mean M i x i x i M i 8,000-16,000 12,000 0.05 600 16,000-24,000 20,000 0.16 3200 24,000-32,000 28,000 0.24 6720 32,000-40,000 36,000 0.28 10,080 40,000-48,000 44,000 0.20 8800 48,000-56,000 52,000 0.07 3640 ____________________________ M n = x i M i = 33,040 g/mol

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(b) Weight-average molecular weight: Molecular wt. Range Mean M i w i w i M i 8,000-16,000 12,000 0.02 240 16,000-24,000 20,000 0.10 2000 24,000-32,000 28,000 0.20 5600 32,000-40,000 36,000 0.30 10,800 40,000-48,000 44,000 0.27 11,880 48,000-56,000 52,000 0.11 5720 ___________________________ M w = w i M i = 36,240 g/mol (c) Degree of polymerization: For polypropylene, the repeat unit molecular weight, m = 3( A C ) + 6( A H ) = (3)(12.01 g/mol) + (6)(1.008 g/mol) = 42.08 g/mol DP = M n m = 33,040 g/mol 42.08 g/mol = 785 (a)  g/mol (b) 36240 g/mol (c) 
Problem 14.8 a. To Find: (a) Wt% of Chlorine to be added (b) How this chlorinated poly-ethylene differs from PVC b. Given: High-density poly-ethylene is chlorinated such that Cl atoms replace 5% of the original H atoms. c. Assumptions: (i) All the Chlorine added is utilized in replacing the existing H atoms – no Cl atom stays unutilized. (ii)

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SolutionsHW9 - HW 9 Problem 14.5 a To Find(a The...

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