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Improving Plastic Materials with Additives


Last updated Dec 21, 2023 | Published on May 20, 2021

From improving heat resistance to increasing structural integrity, there are a number of additives used improve the mechanical properties of thermoplastics..

In our previous blog, we talked about the most common types of thermoplastics used in injection molding and how they compare against each other. Today, we’ll be going over improving the characteristics of resins with plastic additives.

What are Plastic Additives?

Plastic additives are compounds added during the formulation of the resin to improve the mechanical properties of plastic. Whether you are looking to imbue heat resistance, improve structural integrity, increase lubricity, or enhance other characteristics, plastic additives are a great way to heighten current attributes or add new properties to preexisting plastic. At Boyd, we have access to a large variety of plastics additives to solve almost any production challenge.

Below, we’ll be going over a few of the most common types of plastic additives used at Boyd:

Glass and Carbon:

Carbon and glass are commonly used material additives that add structural integrity, toughness, and rigidity to a thermoplastic. They are helpful when a part needs to support weight or endure a harsh environment for extensive periods. While the amount of glass or carbon added to a resin can be highly specified, given how abrasive this additive is, adding too much can prematurely wear down tooling.

Fire Retardants:

Fire retardants are compounds added to plastic resins to help inhibit burning. They are particularly useful for materials such as polycarbonate, which may struggle with flammability restrictions. There are different kinds of fire-retardant additives and many plastics are available with varying amounts of added fire retardant depending on project requirements.

UV Stabilizers:

Plastic components are often subject to damage when exposed to direct sunlight or other ultraviolet light sources. Extended exposure can diminish the mechanical performance and alter the color of a plastic part. Adding UV stabilizers to the plastic can protect components from degradation and discoloration resulting from subjection to ultraviolet rays.


Colorants are plastic additives that alter the color of plastic. Unlike other additives which are added to plastic during formulation, colorants can be mixed in during injection molding to help achieve custom colors. Whether a part needs to match a specific color for branding purposes or simply needs to add contrast to a design, colorants allow most thermoplastics to achieve nearly infinite color possibilities.

Release Agents:

Depending on how a component is designed, it can sometimes be difficult to remove it from the tool. Often, this issue doesn’t arise until later stages in the manufacturing process. Instead of completely redesigning the mold, it’s often simpler to use plastic that contains release agent additives. These additives add lubricity to the component, so it can be easily ejected from the tooling.


Teflon is an additive commonly used for high wear applications or parts that face a lot of friction throughout their lifespan. It can help increase the lubricity of plastic and reduce friction when it makes contact with other components and ultimately improving durability.

We’ve listed the most common additives at Boyd, but it’s far from an exhaustive list. Additives are frequently mixed and matched with different plastics to create custom solutions for tough injection molding challenges. To discuss your specific plastic component needs, schedule a consultation with our experts.

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