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Recycled Plastics Testing and Certification

Demonstrate that your recycled plastics are compliant to UL Solutions materials standards for use in end-applications.

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Component Recognition program for mechanically recycled plastics

We test mechanically recycled plastic compounds with post-consumer or post-industrial content to UL 746S (the Standard for the Evaluation of Sustainable Polymeric Materials for use in Electrical Equipment). The first edition of this standard was published on August 30, 2023. Requirements for mechanically recycled plastic compounds have been transferred from UL 746D (Standard for Safety for Polymeric Materials - Fabricated Parts).

Watch the video: EM Recycled Plastics

As the world becomes more sustainable, recycled plastics hold promise for our future, transforming the way we live, work and build.

At the same time, increasing safety, quality and sustainability goals create challenges and opportunities for recycled plastics manufacturers and suppliers.

Learn more about the importance of testing and certification for mechanically recycled plastics.

The rigorous testing involved in this process makes it possible to assign to a mechanically recycled plastic the same ratings as a virgin resin within the same product category (QMFZ2). It hence allows a virgin resin to be substituted by a mechanically recycled plastic for end-use applications in compliance with UL 746C, the Standard for Polymeric Materials, Use in Electrical Equipment Evaluations - within the design limitations of the specific end-product standards.

UL certification process for mechanically recycled plastics

The certification process includes three parts: initial certification, quality assurance (QA) program, and follow-up inspection visits.

There are two paths for evaluating a mechanically recycled plastic, and each defines the number of batches that are needed to evaluate consistency in the mechanically recycled plastics stream. Customers are encouraged to contact UL Solutions to learn more about which path is required for their specific testing.

Initial Certification

Path 1: Mechanically recycled plastics with consistent identification

This path is typically for post-industrial regrinds that are traded between different companies and, as a result, traceability is compromised.
Three batches are required with the following properties tested:

  • IR – Infrared Analysis
  • TGA – Thermogravimetric Analysis
  • DSC – Differential Scanning Calorimetry
  • Flammability – The results of these tests are to be consistent per criteria in UL 746D

Infographic illustrating three batches with five properties being tested

  • One batch is required for additional short-term properties, i.e., HAI, HWI, CTI, etc.
  • One batch is required for additional colors
  • One batch is required to determine an Elevated Relative Thermal Index (RTI) through LTTA
  • A generic RTI can be assigned based on a positive IR comparison to a generic plastic

Infographic illustrating a batches required for short-term properties, additional colors, RTI through LTTA

Path 2: Mechanically recycled plastics without consistent identification

This path is typically for post-consumer plastics that have been used in products that are considered waste. The plastic in these products is recovered and reprocessed to be reused again in products.

Five batches are required with the following properties tested:

•    Flammability
•    Impact strength
•    Tensile strength
•    Heat deflection temperature
•    Dielectric strength
•    Hot Wire Ignition (HWI) or Glow Wire Ignition (GWI)

Path 2 infographic

One batch is required for infrared analysis (IR)

Infographic illustrating infrared analysis
Three batches are required for additional short-term properties, i.e., HAI, HWI, CTI, etc.

Infographic illustrating infrared analysis
One batch is required for additional colors.

Infographic illustrating one batch being used for additional colors

One batch is required for an Outdoor investigation (UV/Water immersion)

Infographic illustrating a batch for UV/Water immersion

One batch is required to determine an RTI through LTTA.

Infographic illustrating a generic RTI assigned based on a positive IR comparison

A generic RTI can be assigned based on a positive IR comparison to a generic plastic.

Quality assurance program for recycled plastics

Our quality assurance (QA) program involves establishing the traceability of plastic sources. Traceability is an important part of producing a high quality, safe, reliable mechanically recycled plastic. This program helps ensure that the manufacturer is maintaining good control of their many plastic sources.

In order to achieve UL Recognition for a component, a recycled plastic manufacturer must have a registered quality management system that is compliant with International Organization for Standardization (ISO) 9001 or an equivalent internationally recognized standard.

In the QA program, a number of tests can be conducted as indicated in UL 746S; however, the following tests are required based on the flammability rating as indicated below:

UL 94 rating QA test programs
HB Impact plus one additional test from UL 746S, 6.4.4


V-2, VTM-2 or better Impact plus UL 94 flammability, or Impact plus two additional tests from UL 746D, 10.4.4

These tests must be conducted on an ongoing basis as deemed required by the quality management system. During follow-up inspection visits, the field engineer will review records for compliance with these test methods.

Follow-up Services 

Our Follow-Up Services verify continuing compliance with safety requirements through ongoing material assessments such as regular manufacturing visits and sample selection with testing as the material is being produced.

Regrind versus post-industrial recycle content

As defined by UL 746D, regrind specifically refers to reclaimed scrap from molding, such as sprues or runners that are reused in-house at a molding facility. 

Regrind that fits this definition can be re-introduced into the molding hopper to comprise up to 25% where the rest of the 75% is comprised of the same virgin grade that was used to mold the parts where the regrind came from.

It is also possible for this type of regrind to be considered a source of mechanically recycled plastics even if it does not match the basic definition. In other words, regrind that is collected and packaged for shipment to a different molder becomes a source of post-industrial (mechanically) recycled plastics. This occurs because the traceability of the regrind is compromised when it leaves the molder, and an evaluation is necessary to verify this regrind, or post-industrial (mechanically) recycled plastic, is consistent when molded by a different molder.

Recycled content validation

Although UL Solutions' Component Recognition of mechanically recycled plastics program will help ensure that the material tested meets UL Solutions’ stringent safety performance requirements, it does not validate for the type of recycled content used or the percentage used. 

UL Solutions' Environmental Claim Validation program (ECVP) for Recycled Content, does evaluate the amount of recycled content in your products including:

•    Post-consumer recycled content
•    Pre-consumer (post-industrial) recycled content
•    Closed loop recycled content
•    Total recycled content

Partner with UL Solutions for recycled plastics services

UL Solutions is a leading global provider for the production of test specimens, and testing and certification services for innovative plastics. We have been testing plastics since 1941 and are proud to serve the world’s top plastics manufacturers. 

Our safety science leadership and in-depth experience across numerous industries, uniquely positions us to provide our customers with a complete view of how products function within a given system. This is particularly critical in the plastics and components industry, as interactions between substances, parts, systems and the environment in which they are expected to function can be the cause of a significant number of hazards and failures, which are rarely apparent when components are tested individually.

Our worldwide presence allows us to provide local services with a global outlook, enabling you to bring your products to the market efficiently. Our trustworthy reputation provides an important product differentiator in a crowded marketplace, communicating safety and quality to original equipment manufacturers (OEMs), purchasers and regulatory authorities.

Download our resource

Recycled Plastics: Substantiate that your recycled plastics are safe and sustainable

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