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WorksheetsPOLYMERS
Total questions: 10
Worksheet time: 10mins
Which one is NOT the types of thermoplastics?
Polystyrene
Nylon
Phenolics
Polyvinylchloride
Polyethylene
Which one is NOT the reason why polymers are important?
Very compatible with net shape processing
Are cost competitive with metals
require less energy to produce than metals
extreme elastic extensibility when subjected to relatively low
mechanical stress
competitive with glass in some applications
Which one is NOT the limitations of polymers?
Some polymers degrade when subjected to sunlight and other forms of
radiation
Service temperatures are limited to only a few hundred degrees
Low modulus of elasticity
High strength relative to metals and ceramics
can be a distinct limitation in load bearing applications
Which one is NOT TRUE about types of Additives by Functions?
Plasticizers – to soften polymer and improve the flow
Lubricants – to reduce friction and improve the flow
Cross-linking agents - to reduce degradation from sunlight
Fillers – to strengthen polymer or reduce cost
Colorants – pigments or dyes
Which one is NOT TRUE about the Mechanical Properties of Thermoplastics?
High modulus of elasticity and tensile strength
Low tensile strength
Much lower hardness than metals or ceramics
Greater ductility on average
Low modulus of elasticity
All is the Classification of Shaping Processes EXCEPT:
Molded parts that are primarily liquid
Hollow molded parts with relatively thin walls
Castings
Foamed products
Continuous filaments
Which one is the Advantages of three-plate mold?
Allows automatic operation of molding machine
Saves material that otherwise would be scrap in the
unit operation
remove heat from the hot plastic
eject molded part from cavity at end of molding cycle
Eliminates solidification of sprue and runner by locating heaters around the corresponding runner channels
Which one of this is Not True about the Shrinkage factors?
Molding temperature
Compaction time
Injection pressure
Eliminates solidification of sprue and runner by locating heaters around the corresponding runner channels
Fillers in the plastic tend to reduce shrinkage
Which one of this is Not True about Compression Molding?
A widely used molding process for thermosetting plastics
used for rubber tires and polymer matrix composite parts
Molding compound available in several forms: powders or pellets, liquid, or preform
Amount of charge must be precisely controlled to obtain repeatable consistency in the molded product
None of the above
Which one of this is Not True about Transfer Molding?
Air pressure is used to inflate soft plastic into a mold cavity
TS charge is loaded into a chamber immediately ahead of mold cavity, where it is heated
Pot transfer molding - charge is injected from a "pot" through a vertical sprue channel into cavity
Plunger transfer molding – plunger injects charge from a heated well through channels into cavity
Capable of molding more intricate part shapes than compression molding
