Homework 4

Homework 4 - ENMA 300 ENME 382 HW 4 4.3 Below, molecular...

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ENMA 300 – ENME 382 – HW 4 4.3 Below, molecular weight data for a polytetrafluoroethylene material are tabulated. Compute (a) the number-average molecular weight, (b) the weight-average molecular weight, and (c) the degree of polymerization. Molecular Weight Range ( g/mol ) x i w i 10,000–20,000 0.03 0.01 20,000–30,000 0.09 0.04 30,000–40,000 0.15 0.11 40,000–50,000 0.25 0.23 50,000–60,000 0.22 0.24 60,000–70,000 0.14 0.18 70,000–80,000 0.08 0.12 80,000–90,000 0.04 0.07 4.4 Is it possible to have a poly(vinyl chloride) homopolymer with the following molecular weight data, and a degree of polymerization of 1120? Why or why not? Molecular Weight Range ( g/mol ) x i w i 8,000–20,000 0.02 0.05 20,000–32,000 0.08 0.15 32,000–44,000 0.17 0.21 44,000–56,000 0.29 0.28 56,000–68,000 0.23 0.18 68,000–80,000 0.16 0.10 80,000–92,000 0.05 0.03 4.6 Sketch portions of a linear polypropylene molecule that are (a) syndiotactic, (b) atactic, and (c) isotactic.
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