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

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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