MAT E 273 -75 Exam 3 Final Exam Questions Correctly Answered|2024
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Course
MAT E 273
Institution
MAT E 273
________________ refers to scenarios for which a polymer will permanently flow overtime in response a constant applied stress. - ️️Viscoelastic Creep
_____________________________ refers to scenarios for which the stress applied to a polymer must decay over time in order to maintain a constant...
MAT E 273 -75 Exam 3 Final Exam
Questions Correctly Answered
________________ refers to scenarios for which a polymer will permanently flow overtime in response
a constant applied stress. - ✔ ✔ Viscoelastic Creep
_____________________________ refers to scenarios for which the stress applied to a polymer must
decay over time in order to maintain a constant strain. Otherwise, overtime, the polymer chains will slip
and slide past one another in response to a constant applied load and the strain will increase (in
magnitude) - ✔ ✔ Viscoelastic Stress Relaxation
A class of polymer that is commonly used for medical coatings, membranes, and tubing, because it is
relatively inert and also anticoagulant in nature. - ✔ ✔ Silicone
A copolymer that is used for Legos and is a common filament material for 3D printing. - ✔ ✔
Poly(Acrylonitrile-Butadiene-Styrene)
A mechanical response characterized as elastic for short durations, but viscous for long durations. - ✔
✔ Viscoelastic
A natural polymer that is extremely elastomeric, exhibiting very high elastic strains for relatively low
stresses. - ✔ ✔ Poly(cis-isoprene)
A polymer that is transparent in pure form and is hard and brittle. - ✔ ✔ Polystyrene
A polymer that offers an impressively low friction coefficient. - ✔ ✔ Teflon
A room-temperature free electron concentration of approximately 10^16 1/m^3 is a value consistent
with that of _________________________. - ✔ ✔ Undoped Silicon
A room-temperature free electron concentration of approximately 10^29 1/m^3 is a value consistent
with that of __________________. - ✔ ✔ A Typical Metal
A significant advantage that composites offer over most metals (random polycrystals) is highly isotropic
properties, in general. - ✔ ✔ False
A uniform electric field is defined as the potential difference (or ______________ difference) per unit
separation that exists between two points in space. - ✔ ✔ Voltage
A very strong and very tough polymer that is transparent, and therefore useful as a substitute for
ceramic glass. - ✔ ✔ Polycarbonate
Above its glass transition temperature, a polymer is brittle. - ✔ ✔ False
, All factors being equal, the strength of a polymer tends to increase as the degree of polymerization
increases. - ✔ ✔ True
All other factors being equal, a polymer's strength tends to increase as the average chain length of the
polymer increases because of the increased opportunities for secondary bond formation. - ✔ ✔ True
Below the glass transition temperature, polymer chains lose their mobility (they are less capable of
bending, flexing, raveling, and rotating about covalent bonds along the backbone.) - ✔ ✔ True
Composites are single-phase materials by defintion. - ✔ ✔ False
Conductivity in a metal is almost always reduced by the introduction of defects into the lattice.
The factor primarily affected by defects is: - ✔ ✔ Electron Mobility
Consider a laminate composite comprised of unidirectional pre-preg (Carbon-Fiber-Epoxy) sheets that
are fused together in an autoclave.
Of the following options, which configuration is expected to be the least anisotropic in regards to its
mechanical properties?
A) Unidirectional (all sheets have a common and aligned fiber orientation)
Consider a PTFE molecule adjacent to a PVC molecule.
Select all of the secondary bonding types that exist between these two molecules.
- Covalent Bonding
- Interactions between dipoles that are temporarily induced
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