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Which of the following are reasons why injection molding of thermosets is more difficult than injection molding of thermoplastics (two best answers) :


A) allowances must be made for cross-linking of thermosets
B) barrel temperatures must be hotter for thermosets
C) cycle times are longer because of curing
D) thermosets are denser
E) two injection units are required

F) None of the above
G) A) and B)

Correct Answer

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Stretch blow molding is a variation of which one of the following:


A) extrusion blow molding
B) injection blow molding
C) rotational blow molding

D) All of the above
E) B) and C)

Correct Answer

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Which one of the following thermoforming processes requires the most expensive mold:


A) mechanical thermoforming
B) pressure thermoforming
C) vacuum thermoforming

D) All of the above
E) B) and C)

Correct Answer

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Which of the following processes would be applicable to produce hulls for small boats (three best answers) :


A) blow molding
B) compression molding
C) injection molding
D) rotational molding
E) vacuum thermoforming

F) All of the above
G) A) and E)

Correct Answer

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A polymer melt exhibits which of the following properties and characteristics (three correct answers) :


A) becomes less resistant to flow at high shear rates
B) becomes more resistant to flow at high shear rates
C) high viscosity
D) low viscosity
E) Newtonian fluid
F) viscoelasticity

G) A) and D)
H) All of the above

Correct Answer

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Which of the following processes are used to produce plastic sheet and film (three correct answers) :


A) blown-film extrusion process
B) calendering
C) chill-roll extrusion
D) doctor blade method
E) spinning
F) thermoforming
G) transfer molding

H) A) and B)
I) C) and G)

Correct Answer

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The two most common polymer foams are which of the following:


A) polyacetal
B) polyethylene
C) polystyrene
D) polyurethane
E) polyvinylchloride

F) D) and E)
G) None of the above

Correct Answer

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