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HW9 - a Very rapid cooling 100 K/sec b Very slow cooling...

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Chemical Engineering 178 Homework 9 Due 11/14 1.) The following data for the T g of polystyrene as a function of molecular weight was obtained by Fox and Flory ( J. Poly Sci 14 , 315 (1954)) M (g/mol) T g (C) 85,000 100 19,300 89 13,300 86 6650 77 4980 78 3590 75 3041 65 2600 62 2085 53 1675 40 What would be the T g of a theoretically infinite molecular weight sample? 2.) 3.) On one graph draw as accurately as possible a plot of the entropy S of a linear atactic poly(vinylchloride) -(CH 2 -CHCl)-(PVC) melt versus temperature T for the following conditions: The glass transition temperature of PVC is 70°C at a rate of 0.1 K/sec.
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Unformatted text preview: a.) Very rapid cooling, 100 K/sec. b.) Very slow cooling, 10-2 K/sec What would be the effect (increase, decrease, no change) on Tg for sample due to: c.) Crosslinking the PVC with γ-radiation? d.) Copolymerization of PVC with a small amount of styrene? e.) Decreasing the molecular weight of the PVC from 150,000 to 2500 g/mol? f.) Applying a pressure of 2000 MPa? g.) How could you decrease the Tg of PVC to below room temperature without changing the polymer molecules or applying pressure?...
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