ENGM 445 Part 2 (Quiz 3) Question and
answers verified to pass
A polymer melt exhibits which four of the following properties and
characteristics?
a) becomes less resistant to flow as temperature increases
b) becomes less resistant to flow at high shear rates
c) becomes more resistant to flow as temperature increases
d) becomes more resistant to flow at high shear rates
e) high viscosity
f) low viscosity
g) Newtonian fluid
h) viscoelasticity - correct answer a, b, f, h
The coefficient of shear viscosity is defined as which one of the following
a) shear rate divided by shear stress
b) shear rate multiplied by shear stress
c) shear stress divided by shear rate
d) shear stress multiplied by shear rate - correct answer c) shear stress
divided by shear rate
The die swell ratio for a polymer melt has a value that is never less than one.
a) True
b) False - correct answer a) True
, Extrusion is a compression process in which material is forced to flow through
a die orifice to provide long continuous product whose cross-sectional shape
is determined by the shape of the orifice.
a) True
b) False - correct answer a) True
Extrusion is used for thermoplastics and elastomers but rarely for thermosets.
a) True
b) False - correct answer a) True
The forward movement of polymer melt in an extruder barrel is resisted by
drag flow, which is caused by the resistance to flow through the die orifice.
a) True
b) False - correct answer b) False
The extruder characteristic indicates that flow rate in the extruder barrel
increases as head pressure decreases.
a) True
b) False - correct answer a) True
To compensate for die swell, the extrudate is often stretched to offset
expansion from die swell.
a) True
b) False - correct answer a) True
Turbulent flow of polymer melt through the die orifice is likely to cause which
one of the following defects in plastic extrusion.
a) melt fracture
answers verified to pass
A polymer melt exhibits which four of the following properties and
characteristics?
a) becomes less resistant to flow as temperature increases
b) becomes less resistant to flow at high shear rates
c) becomes more resistant to flow as temperature increases
d) becomes more resistant to flow at high shear rates
e) high viscosity
f) low viscosity
g) Newtonian fluid
h) viscoelasticity - correct answer a, b, f, h
The coefficient of shear viscosity is defined as which one of the following
a) shear rate divided by shear stress
b) shear rate multiplied by shear stress
c) shear stress divided by shear rate
d) shear stress multiplied by shear rate - correct answer c) shear stress
divided by shear rate
The die swell ratio for a polymer melt has a value that is never less than one.
a) True
b) False - correct answer a) True
, Extrusion is a compression process in which material is forced to flow through
a die orifice to provide long continuous product whose cross-sectional shape
is determined by the shape of the orifice.
a) True
b) False - correct answer a) True
Extrusion is used for thermoplastics and elastomers but rarely for thermosets.
a) True
b) False - correct answer a) True
The forward movement of polymer melt in an extruder barrel is resisted by
drag flow, which is caused by the resistance to flow through the die orifice.
a) True
b) False - correct answer b) False
The extruder characteristic indicates that flow rate in the extruder barrel
increases as head pressure decreases.
a) True
b) False - correct answer a) True
To compensate for die swell, the extrudate is often stretched to offset
expansion from die swell.
a) True
b) False - correct answer a) True
Turbulent flow of polymer melt through the die orifice is likely to cause which
one of the following defects in plastic extrusion.
a) melt fracture
