Lecture28

# Lecture28 - EMA 6165 Polymer Physics Crystallinity Lecture...

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07/21/11 EMA 6165 Polymer Physics - Lecture 34 1 EMA 6165 - Polymer Physics Crystallinity Lecture 28 Professor Anthony Brennan Department of Materials Science & Engineering University of Florida

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07/21/11 EMA 6165 Polymer Physics - Lecture 34 2 Rate of growth If h f is known one can calculate σ e Huseby, Bair, Salovey measured P.E. that was gamma irradiated to prevent thickening σ e = 93 ± 8 ergs/cm 2 T m o = 146 o C
07/21/11 EMA 6165 Polymer Physics - Lecture 34 3 Rate of growth at high T f = ( 29 h T T f m o f where ( 29 f T T T m o = + 2

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07/21/11 EMA 6165 Polymer Physics - Lecture 34 4 Rate of growth Isotactic PS: T m = 242 o C T g = 110 o C T = 132 o C Still crystallizes Normally h f does not change as a function of temperature - HOWEVER -
07/21/11 EMA 6165 Polymer Physics - Lecture 34 5 Rate of growth Hoffman does not account for surface roughness in this model whereas others have via the term, for l g * = 2 σ e f + δ l isothermal conditions

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07/21/11 EMA 6165 Polymer Physics - Lecture 34 6 Rate of growth When v “stems” and v f = v - 1 “folds” have been formed the free energy of formation (ignoring chain ends) ∆φ v = ( 29 2 bl fold energy work σ + 2 v f ab e surfaceenergy of fold σ - vabl f for v >>1
07/21/11

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Lecture28 - EMA 6165 Polymer Physics Crystallinity Lecture...

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