Plastic Additives and Their Importance in Recycled Materials

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Plastic Additives

Plastic additives are typically added to base polymer plastics in order to improve their properties and make them suitable for a range of applications. Particularly in the pipe extrusion industry, additives are extensively used to color, improve strength and enhance base plastics properties. Equally important is the role of plastic additives in plastics that have been recycled, reground or are off-spec, since in this case the base plastic starts off with lower grade properties.

Common types of plastic additives
UV inhibitors

A common additives group used in pipe extrusion as well as any plastic designed for outdoor use or exposure to sunlight, is UV light stabilizers or inhibitors. These additives protect plastic products from UV light by inhibiting the reactions that cause the chemical degradation of the plastic, ensuring a longer product service life despite exposure to sunlight.

Impact modifiers

Impact modifiers improve the plastics behaviour to impact and shock, making it more robust and less brittle or prone to cracking.


Pigments are added in pellet, powder or liquid form to the base plastic raw material, in order to achieve a particular product color.

Plastic additives for recycled materials

Using recycled plastic in pipe extrusion is desirable both for its environmental as well as economic benefits. By utilizing technologies such as the DRTS 3-layer cross head, as much as 90% of the produced pipe can be made with regrind, recycled, or off-spec material. This in turn significantly reduces the operations carbon footprint and offers substantial raw material cost savings.

However, recycled plastic differs from virgin raw material in two respects. Firstly, it has undergone processing, resulting in some level of degradation and worsening of its characteristics. Second, the recycled polymers often don’t come from the exact same plastic, resulting in incompatibility issues in the recycled plastic mix. This is the reason that recycled plastics need re-stabilization, in order to produce quality products within specification. To enhance the recycled plastics mechanical properties and to provide protection against degradation, stabilizers as well as fillers and impact modifiers can be added.


Oftentimes, recycled plastics blends are incompatible and can produce products with unstable morphologies.
This is why compatibilizers are added to the blend of polymers in order to increase the stability, as well as mechanical properties of the plastic products.

Impact modifiers

The impact resistance of recycled plastic can be significantly impaired, leading to the manufacturing of off-spec products. Impact modifiers are added to the recycled plastic so that the resulting products exhibit all of their attributes within specifications.

Stabilizing agents

In recycled materials, degradation occurs and the plastics lose their effectiveness causing products to go off-spec during the plastic’s second lifetime. For this reason, stabilizing agents are often added to the recycled plastic mix, in order to hinder the plastics degradation, as well as improve its mechanical properties.

Learn more with DRTS

To read more about using recycled plastic in pipe extrusion, as well as gain an insight into the current state and latest trends in pipe extrusion technology, download your copy of the DRTS 2018 Pipe Extrusion Technology Report. Or feel free to contacts DRTS for a free expert consultation.

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