A molten thermoplastic polymer is made into a large 3-dimensional solid action figure. The polymer is melted and processed using injection molding, where the polymer melt is squirted into a cold metal mold, where it solidifies. When thick parts are molded from a highly crystalline polymer (e.g., polyethylene or isotactic polypropylene), they sometimes exhibit "sink marks," where the surface of the part has actually sunk away from the mold wall. A. Explain why. Hint: Polymers have very low thermal diffusivity. B. How would an amorphous (non-crystallizable) polymer perform in injection molding? C. Can a thermoset be used in injection molding? If so, describe the process. If not, explain one method that could be used form a thermoset polymer in the shape of a mold.
A molten thermoplastic polymer is made into a large 3-dimensional solid action figure. The polymer is melted and processed using injection molding, where the polymer melt is squirted into a cold metal mold, where it solidifies. When thick parts are molded from a highly crystalline polymer (e.g., polyethylene or isotactic polypropylene), they sometimes exhibit "sink marks," where the surface of the part has actually sunk away from the mold wall. A. Explain why. Hint: Polymers have very low thermal diffusivity. B. How would an amorphous (non-crystallizable) polymer perform in injection molding? C. Can a thermoset be used in injection molding? If so, describe the process. If not, explain one method that could be used form a thermoset polymer in the shape of a mold.
Chemistry
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Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
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Chapter1: Chemical Foundations
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Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
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Transcribed Image Text:6.4 A molten thermoplastic polymer is made into a large 3-dimensional solid action figure. The polymer
is melted and processed using injection molding, where the polymer melt is squirted into a cold
metal mold, where it solidifies. When thick parts are molded from a highly crystalline polymer
(e.g., polyethylene or isotactic polypropylene), they sometimes exhibit "sink marks," where the
surface of the part has actually sunk away from the mold wall.
A. Explain why. Hint: Polymers have very low thermal diffusivity.
B. How would an amorphous (non-crystallizable) polymer perform in injection molding?
C. Can a thermoset be used in injection molding? If so, describe the process. If not, explain one
method that could be used form a thermoset polymer in the shape of a mold.
Expert Solution
Step 1
Types of plastic:
- Thermoplastic polymer
- Thermosetting polymer
Mostly thermoplastic polymers are used in injection moulding.
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