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Chapter 15: Problem 46

Which of the following polyethylene thin films would have the better mechanical characteristics: (1) formed by blowing, or (2) formed by extrusion and then rolled? Why?

Short Answer

Expert verified
Answer: The polyethylene thin film formed by blowing has better mechanical characteristics due to its more uniform and balanced material structure.

Step by step solution

01

Understand the Blowing and Extrusion Processes

Blowing is a manufacturing process where polyethylene is melted and extruded into a thin tube, which is then inflated and cooled to form a thin film. Extrusion, on the other hand, involves forcing the polyethylene through a die to create a continuous film, which is then cooled and rolled.
02

Mechanical Characteristics of Blown Films

Blown films generally have better mechanical characteristics, such as tensile strength, elongation, and impact resistance. This is because the blowing process stretches the polymer chains in both the machine and transverse directions, resulting in a more balanced and uniform material structure.
03

Mechanical Characteristics of Extruded and Rolled Films

Extruded and rolled films, on the other hand, do not stretch the polymer chains as much as the blown films, which can lead to a less balanced material structure. As a result, extruded and rolled films often have lower tensile strength, elongation, and impact resistance, compared to blown films.
04

Conclusion

Based on the analysis of the two processes and their effects on the mechanical characteristics of polyethylene thin films, it can be concluded that the polyethylene thin films formed by blowing would have better mechanical characteristics than the ones formed by extrusion and then rolled. This is due to the more uniform and balanced material structure provided by the blowing process.

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Most popular questions from this chapter

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