Question

Which one of the following statements is FALSE with respect to the injection molding of polymer composite?

• A. Molten polymer along with the reinforcement is injected into a closed mold cavity.
• B. Material deforms plastically to adopt the shape of the mold cavity.
• C. Melt temperature, injection speed, and screw speed are some important process parameters.
• D. Commonly used reinforcements are particles, whiskers, and short fibers.

Hint:

In injection molding, the material flows into the mold cavity, but it does not deform plastically as in metalworking processes. Understanding the process parameters such as injection speed and temperature is crucial for optimal product quality.

Answer 1

The Correct Option is B

In injection molding of polymer composites, the process involves injecting molten polymer mixed with reinforcements into a closed mold cavity. Let's break down the given options:
- Option (A): This statement is true. In injection molding, molten polymer along with the reinforcement is injected into a closed mold cavity, where it is shaped into the desired form.
- Option (B): This is the false statement. Injection molding does not involve plastic deformation of the material in the same way as metal forming. The material flows under pressure to fill the mold cavity, but it does not deform plastically. The process relies more on the material’s flow properties when molten.
- Option (C): This statement is true. Melt temperature, injection speed, and screw speed are indeed important process parameters in injection molding, as they control the material flow and quality of the final product.
- Option (D): This statement is true. Commonly used reinforcements in polymer composites include particles, whiskers, and short fibers. These reinforcements improve the mechanical properties of the composite material.
Therefore, the correct answer is (B) because the material does not deform plastically but flows into the mold cavity.