Author Question: You have been asked by your company to evaluate making camper shells for trucks by either rotational ... (Read 68 times)

Bernana · **on:** Aug 19, 2018

You have been asked by your company to evaluate making camper shells for trucks by either rotational molding or by thermoforming. Give a description of these processes and compare their advantages and disadvantages for this specific part.

What will be an ideal response?

Question 2

In what ways does crystallinity affect the thermal properties of a polymer? Contrast crystalline polymers with amorphous polymers throughout the entire thermal range of a polymer.

What will be an ideal response?

mbcrismon · **Reply #1 on:** Aug 19, 2018

Answer to Question 1

Rotational Molding: use a closed mold and resin powder. The mold is placed in a machine that rotates the mold and material along two axis allowing for complete coverage of the material as it reaches its glass transition temperature and fuses along the mold wall. Three stages are included in this process, loading/unloading, heating, and cooling. Used for making hollow parts or multiple parts at one time (requiring post-molding processing). Careful consideration of temperatures, length of time in the mold, type of material, etc. should be considered when doing this process as bridging, pitting, and warping can occur.

Thermoforming: use a sheet of plastic material that in put over an oven and heated to it's glass transition temperature until is bows. Then the material is brought over an open mold and depending on the orientation of the mold

Answer to Question 2

Crystallinity raises melting temperature, amorphous polymers have a Tg because there is no pure crystalline part, HDT is higher with crystallinity, decomposition temperature will NOT appreciably change.