16.1 A polymeric support made of poly(methyl methacrylate), PMMA (Tg = 80 °C), has been used in a prototype for a load-bearing part, and it must have a minimum relaxation modulus (Er,min) of 1.00 MPa, when used at 120 °C. You need to determine the service lifetime of the part. Given data for the 5-hour relaxation modulus, Er, (which is just E on the graph) as a function of temperature below, use the WLF equation to: (A) estimate how long (in days) the part can be safely used at 120 °C before needing replacement. (B) estimate how long (in days) the part can be safely used at 80 °C before needing replacement. (Note: 1 MPa = 106 Pa) Hint: start with the temperature where the modulus, Er, reaches the minimum relaxation modulus. log E (Pa) 14 13 12 11 10 2987654 0 20 40 60 80 100 120 Temperature °C O ✪ 140 160 180 200

16.1 A polymeric support made of poly(methyl methacrylate), PMMA (Tg = 80 °C), has been used in a prototype for a load-bearing part, and it must have a minimum relaxation modulus (Er,min) of 1.00 MPa, when used at 120 °C. You need to determine the service lifetime of the part. Given data for the 5-hour relaxation modulus, Er, (which is just E on the graph) as a function of temperature below, use the WLF equation to: (A) estimate how long (in days) the part can be safely used at 120 °C before needing replacement. (B) estimate how long (in days) the part can be safely used at 80 °C before needing replacement. (Note: 1 MPa = 106 Pa) Hint: start with the temperature where the modulus, Er, reaches the minimum relaxation modulus. log E (Pa) 14 13 12 11 10 2987654 0 20 40 60 80 100 120 Temperature °C O ✪ 140 160 180 200

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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