Chapter 15.3

Chapter 15.3 - Viscoelastic Creep Many polymers susceptible...

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12 MSE 2090: Introduction to Materials Science Chapter 15, Processing of Polymers Viscoelastic Creep Many polymers susceptible to time-dependent deformation under constant load – viscoelastic creep Creep may be significant even at room temperature and under moderately low stresses (below yield strength) Results of creep tests are described by time dependent creep modulus: E c (t) = σ o / ε (t) Amount of creep decreases as crystallinity increases
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13 MSE 2090: Introduction to Materials Science Chapter 15, Processing of Polymers Fracture of Polymers ¾ Fracture strengths of polymers are low compared to metals and ceramics ¾ Brittle fracture occurs in thermosetting polymers. Fracture is initiated at stress concentrators (scratches, notches, etc). Covalent bonds are severed during fracture ¾ In thermoplastic polymers, both ductile and brittle fracture are possible. Brittle fracture is favored at lower temperatures, higher strain rates, and at stress concentrators ¾ Brittle to ductile transition often occurs with increasing temperature
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This note was uploaded on 02/14/2012 for the course MSE 2090 taught by Professor Leoindzhiglei during the Fall '10 term at UVA.

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Chapter 15.3 - Viscoelastic Creep Many polymers susceptible...

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