Structural foam molding is an injection molding process that uses low pressure plastic injection to form large parts.

A gas is introduced into the melt by Direct Injection or by a Chemical Foaming Agent.

The gas remains dissolved in the melt while the melt is under pressure. As the melt is injected into the mold the pressure is reduced allowing the gas to expand the polymer.

Foamazol™ chemical foaming agents control the size and distribution of the cells or bubbles in the expanding melt.
For additional information on using chemical foaming agents in structural foam molding, please click here

Co-Injection injection molding, also known as sandwich molding, allows for the injection of two
dissimilar plastics. One injection unit shoots a solid plastic, the other a plastic containing a chemical foaming agent.

The solid plastic injection stage begins a split second before the foamed plastic stage causing the foamed plastic to move to the inside of the solid material. The end product displays a solid skin with a foamed core.

 Foamazol™ chemical foaming agents yield a good density reduction while maintaining a good surface appearance.

Gas counter-pressure molding is an injection molding process where the mold is pressurized with an inert gas.

This pressure pushes the injected foam melt against the mold walls forming a hard, solid skin.

The inert gas is then released from the mold allowing the foam to expand within the part.

Foamazol™ chemical foaming agents will give good density reduction while retaining good appearance.

Rotational Molding

Rotational molding consists of 4 main steps

Generally, the plastic raw material is in the form of powder or fine granules. After being filled with the raw materials, the molds are moved inside an oven and either spun on two different axis or spun on one axis and rocked back and forth on the other.

As the mold rotates in the oven, the plastic material continues to tumble against the mold walls until it begins to flux or melt. As the plastic melts it sticks to the mold walls coating them to form the part.

After the heating cycle, the mold is moved to a cooling station, and once sufficiently cooled the mold is opened and the part removed.

Foamazol™ chemical foaming agents will yield lighter more buoyant parts with better insulating Properties.

Chemical Foam Extrusion

During the chemical foam extrusion process plastic resin and chemical foaming agents are mixed and melted. The chemical foaming agent decomposes liberating gas which is dispersed in the polymer melt and expands upon exiting the die. Typically foamed profile extrusions require more intense cooling than solid profiles due to the insulation properties of the foam structure.

Most Foamazol™ chemical foaming agents formulations are self nucleating resulting in very fine celled foams and faster extrusion rates.

Direct Gas Extrusion

In direct gas extrusion gases such as nitrogen, carbon dioxide, pentane, butane, etc. are injected under high pressure directly into the polymer melt. 

Chemical foaming agents are used in this process to nucleate the foam. This results in a finer and more uniform cell structure from the expansion of the injected gas.

The efficient nucleating effects of Foamazol™ chemical foaming agents can reduce the amount of physical gases required.

Today there is a tremendous amount of activity in wood plastics composites. Some processors are using wood and plastic while others are using wood, plastic, and foaming agents. This is a typical profile extrusion process, however, the high moisture content of wood flour must be addressed.

Bergen has developed some special Foamazol™ chemical foaming agent grades for this process, and find that specific polymer/wood content blends require specific foaming agent formulations. Bergen is ready to assist you on developing the best product for your specific needs.

Typically, foaming agents are used in the manufacture of co-axial cable. These cables usually have a foamed polymer layer that is used for insulation. The foamed insulation layers must have a uniform cell structure.

Foamazol™ chemical foaming agents produce a uniform cell structure.