ADVANCEMENTS IN PLASTICS ADDITIVES WHAT TO CONSIDER

Plastic additive technology has made some massive advancements over the past 10 years, but with all of the different options available how cansomeone choose which path to go down? The term"additives" is a loose one, so we firt need to clarifv what we're referring to. The basicdefinition is something that is added to a base polymer for performance enhancements, typically with a low percentage of the overall resinmakeup.

We have broken the “additives” into a few distinct categories; Blowing Agents, Fillers, and Plasticizing Agents.

Blowing Agents

Blowing agents have been around for 10+ years, however, as advancements continue the usage has become more frequent in the industry. These agents are used in a variety of applications and processing techniques, A blowing agent is a substance that is capable of producing a cellular structure via a foaming process in a variety of materials that undergo hardening or phase transition, such as polymers, plastics, and metals. They are typically applied when the blown material is in a liquid stage.

What’s the benefit of this new cellular structure?

Through a reaction within the polymer, a blowing agent reduces density, increasing thermal and acoustic insulation, while increasing the relative stiffness of the original polymer. That sounds great, right? But how much reduction could you see in your density/part weight? What about cycle time reductions?

According to the data, there is a high likelihood that you can reduce overall part weight by up to 20% and reduce your cycle time by 20%. The key to achieving the maximum density and cycle time reduction will depend on the part design/geometry and the injection molding machines capabilities. If your injection molding machine has a very low and limited injection rate, then this can hinder the processing of a blowing agent to achieve maximum results.

How does this additive get blended?

The blowing agent is blending into your molding process similarly to how a colorant is blended, with most companies using a gravimetric blender feeding the colorant/blowing agent or other additives directly into the throat of the screw/barrel assembly with typically a mixture ratio of 4%.

Once the material is fed into the screw and barrel, the chemical process takes over, and adjustments in the injection profile have to be made for the agent to react and “do the work for you”. If you don’t make those adjustments, then you are bypassing the purpose of the agent and won’t see any results.