PTFE4775_Practiceprobs_Exam2

PTFE4775_Practiceprobs_Exam2 - For some of these questions...

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Unformatted text preview: For some of these questions, you may need to use parameters / data given in class or in Polym e r Handboo k . 1) We have a polymer PX dissolved in some solvent S. For each of the following variable, a) determine whether it is a property of the polymer only, of the solvent only, or of the polymer-and-solvent pair, b) state its unit. M n , M v , M w , PDI, , R g , R h , A 2 , osmotic pressure), , Mark Houwink K and a, V h , L contour , V 1 . 2) True/False. The intensity of light scattered from a particle such as a polymer chain depends on the mass of the particle, not on its volume. True/False. If a pure solvent is separated from some polymer solution by a membrane that is only permeable to the solvent molecules, a higher pressure will develop in the pure solvent. True/False. For a polymer and a solvent with known K and a values, it is possible to figure out M n , M w , and PDI from a GPC measurement even in the absence of any standard for calibration. True/False. For 10 kg of polystyrene where there are 1 mol of polymer chains, the molecular weight is 10 kg/mol. (Mol. wt. of repeat unit = 100 g/mol) True/False. The average mol. wt. found in light scattering can be higher than that found in osmotic pressure measurement. True/False. For a polymer solution, increasing the concentration of polymer typically results in higher [ ]. 3) Fill in the blanks with < , > , or = For a polymer in a theta solvent: ____ 0.5; Mark-Houwink constant a ____ 0.5. For a polymer in a good solvent: ____ 0.5; Mark-Houwink constant a ____ 0.5. Volume of a polymer chain in a solvent _____its volume in a good solvent 4) Cal c ulat e th e G mix for the process of mixing 100 mL toluene and 2.0 grams of PVC at 23 o C. Assumption: Flory-Huggins model works well for this system. Data: mol . wt . (g / mol) d e n s ity (g / c m 3 ) (MPa 1 / 2 ) Toluene: 92.1 0.86 18.3 PVC: M w = 150,000 1.45 21.5 PDI = 1.5 The parameter has been measured before and reported as a function of temperature: = (132 K) / T + 0.30 5) Problem 2 and 3 in textbook on page 395....
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PTFE4775_Practiceprobs_Exam2 - For some of these questions...

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