UL's testing programs for plastics cover plastic materials and related products for use in components and parts of end-products and appliances. Whether it is basic UL Recognition or publication of specific thermal, mechanical and electrical characteristics, UL will provide the appropriate information and service effectively and efficiently.

The plastic material characteristics published on the UL Recognition card enable users of the UL-Recognized plastic to acquire UL Certification for the product or device with a reduced test program. UL Recognition for a plastic material is not limited to the plastic manufacturer. End users can acquire UL Recognition for a plastic material or have their end products subjected to alternative tests.

Material Testing and the UL Thermoplastics Testing Center

The UL Thermoplastics Testing Center (TTC) carries out tests for all major plastics applications, ranging from polyethylene to high-performance thermoplastics. The TTC works with companies involved in compounding, extrusion and injection molding, as well as raw materials producers and automotive manufacturers and their suppliers. The Center uses robots and state-of-the-art machinery to offer one-stop service for customers and can manage approximately 200 different tests for thermoplastics, as well as the production of granules and test pieces. The production of test pieces is carried out using fully automated injection molding machines. The center uses approximately 100 different injection molds for use in tests under UL, ISO and CAMPUS standards and also has complete production lines which enable the compounding of ABS and its blends, polycarbonates and industrial thermoplastics in quantities ranging from 1.3 to 100 kilograms. 

Material preselection

The preselection of materials is a valuable tool for helping product designers find materials that comply with safety standards. To reduce the risk of products being delayed to market, product designers need to select materials that mitigate the risks of fire, electric shock, personal injury and environmental hazards as well as comply with established North American and international safety standards. For additional information, download the material preselection free white paper or the presentation on thermal management & preselection for solder limits presented at the 2008 IPC/APEX designers summit.

UL iQTM for plastics database

Besides testing and certifying plastics, UL has developed UL iQTM for plastics, a powerful database free to users that allows the preselection of materials by providing searches of more than 60,000 grades of UL-Recognized plastics based on the requirements of a specific application. Search by product specifications, company name, file name, generic family, grade and description to get the appropriate plastic. It also facilitates the preselection of materials based on RoHS compliance.

Plastics testing

The evaluation of plastic materials may include the determination of material flammability (burning characteristics), ignition characteristics from various thermal and electrical sources, electrical tracking and other electrical characteristics, and analytical tests. In addition, the effect of long-term exposure to elevated temperature (air-oven aging), water, ultraviolet light, cold, etc., on property-retention may be evaluated.

Properties evaluated by UL include

  • UL 94 flammability
  • UL 746A electrical and mechanical properties
  • UL 746B thermal-aging program
  • UL 746C file review
  • Outdoor suitability program for plastics
  • Components -- concentrates
  • Color concentrates

Materials for use in special environments is the investigation of materials for specific end-use product applications where requirements exist for the retention of properties after exposure to certain critical operating and/or environmental conditions. This would include exposure to various types of ultraviolet (UV) radiation.

Basic UL Recognition testing program

The basic testing program to achieve UL Recognition involves three identification tests: infrared spectroscopy (IR), thermogravimetry (TGA) and differential scanning calorimetry (DSC). In addition, since most end users benefit from plastics being flame-rated, most UL Recognized plastics products include flame classification.

Once the identification and/or flame tests are successfully completed, a unique grade designation is published. Thereafter, UL field representatives conduct quarterly Follow-Up Services visits to each manufacturing location. In addition, the plastic is picked up annually and sent to UL for comparison to the IR, TGA and DSC reference graphs on file. Flame testing is required if the plastic material is vertically rated.

Successful comparison to the archived reference IR, TGA and DSC is an indication that no polymeric change(s) have occurred and is evidence that mechanical and electrical properties of the material remain unchanged. Successful correlation of flame class between Follow-Up Services and the published rating are also required to maintain UL Recognition for the product. Should any of the above tests not comply, action is taken to remove Recognition or downgrade the plastic. This usually includes a mandatory name change as an indication of a degraded characteristic variation.

Plastics with "flame only" Recognition are selected (for use in end-products) for their flame characteristics only. Electrical and mechanical properties are more than likely evaluated on the end product or possibly not required based upon their application. Despite the fact that the mechanical and electrical characteristics of the material were not evaluated, UL's liability rests in the evidence that the untested properties remain unchanged (via IR, TGA and DSC comparison to reference).

The continued publication of a specific material (with a specific designation or name) enables the continued use of that plastic material in end-use products, so long as the original characteristics are maintained. Besides the obvious safety aspects of using a Recognized plastic material, end-product users (of the Recognized plastic) are subject to a reduced test program of the product, and similar advances apply to the use of UL Recognized switches, appliance wire, terminal blocks, etc.

UL Yellow Card

UL Marks and labels

There are many types of UL Marks, each with its own specific meaning. The only way to determine if a product has been certified by Underwriters Laboratories® is to look for the UL Mark on the product itself. In a few instances, the UL Mark may be present only on the packaging of a product.

Some products certified by UL are components that are intended to be used in the manufacture of a complete Listed product. These components cannot bear the UL symbol, but may use a special Recognized Component Mark.

The UL Mark on a product means that UL has tested and evaluated representative samples of that product and determined that they meet UL requirements. Under a variety of programs products are periodically checked by UL at the manufacturing facility to make sure they continue to meet UL requirements. The UL Marks may be only used on or in connection with products certified by UL and under the terms of written agreement with UL. In addition to these marks, UL also provides access to the marks required in a number of other key world markets.

About UL Mark Product Certification

The following information pertains to UL product certification programs accredited by the U.S. Occupational Safety & Health Administration (OSHA), the American National Standards Institute (ANSI), and the Standards Council of Canada (SCC).

UL operates under its own authority as an independent, not-for-profit, nongovernmental organization.

To establish certification, samples of a product submitted by manufacturers for certification are tested and evaluated. If UL decides the product fulfills all applicable requirements it authorizes the manufacturer to apply a certification mark to production of the samples submitted, or issues a certificate or notification that the product is now certified by UL. A report of the evaluation is provided to the manufacturer. Before the manufacturer releases products with a certification mark, UL must initiate Follow-up Service in which periodic audits of products at the factory are completed by UL Field Representatives (see FUStart for more information about UL Follow-Up Service). These audits are described in a Follow-Up Service Procedure that is created as part of the initial evaluation of the product. For some products, factory samples are selected for retesting at UL. Certification continues until the manufacturer requests termination or fails to fulfill a requirement. UL must evaluate modifications to certified products before the modified product is authorized to bear the Mark or be considered certified.