Processing Tips

Processing Tips Overview: Physical and Chemical Foaming Agents

Basically, there are two types of foaming agents — physical and chemical foaming agents.

Physical foaming agents are gases (nitrogen, carbon dioxide, pentane, butane), to name a few that are injected under high pressure directly into the polymer melt.

Foamazol™ chemical foaming agents are used in this process to nucleate the foam structure that results from the expansion of the gas that is injected.

Chemical foaming agents are chemical substances that decompose during heating generating gasses which are dispersed through the polymer melt.

To obtain a uniform cell structure with either a physical or chemical foaming agent, the gas is either injected or evolved by heat and must be thoroughly dispersed in the polymer melt.

Some of the essential factors are:

  • particle size of the foaming agent
  • dispersive properties of the machine
  • decomposition rate of the foaming agent
  • melt viscosity of the thermoplastic resin being processed

Foamazol™ Chemical Foaming and Nucleating Agents is a plastics additive that produces a cellular structure in plastic products.

With sufficient heat Foamazol™ chemical foaming agents decompose to generate gas which expands the plastic by forming bubbles, or cells, within the resin.

Chemical foaming agents are typically broken down into two main groups: Exothermic & Endothermic.

Exothermic Chemical Foaming Agents

Exothermic CFAs are chemicals that generate heat during the decomposition process thus, Exothermic.

The exothermic chemical foaming agents are organic in nature and give off N2 gas when they decompose.

They liberate more gas per gram of foaming agent than endothermic agents and higher gas pressure.

The decomposition temperature of exothermic foaming agents can be raised or lowered by the addition of kickers.

So your finished products are stronger, weigh less and look better.

Endothermic Chemical Foaming Agents

Endothermic CFAs are chemicals that take heat away from the chemical reaction; thus Endothermic. They are based on inorganic chemicals and generate CO2 gas. This produces foams with a much smaller cell structure, resulting in improved appearance and better physical properties. And, Foamazol™ Endothermic chemical foaming agents contain no hazardous materials so they are environmentally friendly, safe to process and grades are available for applications where contact with food occurs.

ENDO/EXO Blend Chemical Foaming Agents

Today, there are blends of both endothermic and exothermic CFAs. These blends can have a synergistic effect that offers benefits over the use of either an endo or exo by themselves Bergen International prides itself on our ability to work with you to develop the exact blend that offers the best set of performance/cost benefits for your specific process and polymer.