Methods for microcellular injection molding

A method of producing a plastic part using microcellular injection molding, comprising:

• providing a polymer;
• heating the polymer to melt the polymer;
• adding a supercritical fluid to the melted polymer to produce a single-phase polymer-gas solution;
• adjusting at least one of the polymer and the supercritical fluid to control at least one of a weight of the plastic part and a surface characteristic of the plastic part;
• and
• injecting the melted polymer with the supercritical fluid therein into a mold;
• wherein injecting the melted polymer with the supercritical fluid therein into the mold causes a pressure drop of about 0.5 bar to about 2.5 bar that causes the supercritical fluid to nucleate in the melted polymer.

A method of molding a tampon applicator, comprising:

• providing a polymer comprising a low density polyethylene resin;
• heating the polymer to melt the polymer;
• adding nitrogen gas to the melted polymer to produce a single-phase polymer-gas solution;
• adjusting at least one of the polymer and the nitrogen gas to control at least one of a weight of the tampon applicator produced and a surface characteristic of the tampon applicator produced;
• injecting the melted polymer with the nitrogen therein into a mold;
• and
• cooling the mold;
• wherein injecting the melted polymer with nitrogen therein into the mold causes a pressure drop of about 0.5 bar to about 2.5 bar that causes cells of the nitrogen to nucleate in the melted polymer.