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PTFE4775_EXAM2 - Q u est ion 1 a In a polyme r solut ion...

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Qu e s tion 1 a) In a poly m e r s olu t ion , c hoo s e how t h e f ollowing variabl e s will c hang e i f w e kee p t h e poly m e r , s olv e n t , and t e m p e ra t ur e t h e s a m e bu t in c r e a s e t h e poly m e r c on ce n t ra t ion . (you do no t hav e t o ju st i f y your an s w e r) i) no c hang e interaction parameter is defined on a per contact basis; not affected by c ii) M w ` no c hang e property of polymer only; doesn’t depend on c iii) of solution in c r e a s e s more stuff in solution, more hindrance / resistance to flow iv) /c not e nough info depends on A 2 : /c increases if A 2 > 0, decreases if A 2 < 0, no change if A 2 = 0 v) [ ] no c hang e [ ] defined for c 0; not a property of c b) Na m e t wo m ain di ff e r e n ce s in t h e ba s i c a ss u m p t ion s o f t h e id e al s olu t ion m od e l and t h e Flory-Huggin s m od e l . i) Ideal solution assumes there is no extra interaction, Flory-Huggins accounts for this using parameter ii) Ideal solution assumes the size of the two components are the same, Flory-Huggins takes into account size difference c ) On t h e c har t b e low , indi c a t e t h e b e havior o f a dilu t e poly m e r s olu t ion by drawing a lin e or c urv e . Also draw s k e t c h( e s ) of th e polym e r c hain s to explain the behavior. You do not need to write out explanations. viscosity strain rate or flow rate d) For e a c h o f t h e f ollowing ind e p e nd e n t c a s e s , d e t e r m in e t h e M n a ss u m ing t h e poly m e r i s 100% lin e ar (no bran c hing) . I f t h e r e i s no t e nough in f or m a t ion , wri t e down wha t addi t ional pi ece o f in f or m a t ion i s n ee d e d t o g e t M n .
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