What is VALOX® FR Resin 357?

VALOX® FR Resin 357 is a thermoplastic polyester resin with outstanding physical and electrical properties, rendering it a suitable material for electrical components. It is a mix of polybutylene terephthalate (PBT) and polycarbonate (PC) that is unfilled and impact modified. One key feature is its flame retardancy, which complies with the flame rating UL-94 (V0/5VA/HB).

Here, you will learn about:

  • What thermoplastics are
  • The VALOX® family
  • The different features and properties of VALOX® FR Resin 357
  • How VALOX® FR Resin 357 is processed
  • The different application areas of VALOX® FR Resin 357

Thermoplastics and the VALOX® family

Thermoplastics are a type of plastic that offers high-strength, very good flexibility, and a resistance to shrinkage. They usually have low melting points, high impact resistance, and excellent chemical resistance. Their physical properties allow them to be recyclable and reusable and very easily repairable. Some types of thermoplastic materials include polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polybutylene terephthalate (PBT), polycarbonate (PC), and polyethylene terephthalate (PET).

VALOX® FR Resin 357 is part of the VALOX® family, a group of thermoplastic polyester resins that are fast-crystallising semi-crystalline materials. These materials are usually based on polybutylene terephthalate (PBT) and/or polyethylene terephthalate (PET). This gives them the necessary properties needed in challenging end-user environments.

Manufactured by SABIC, VALOX® is a family of numerous grades, each built for specific applications and with particular physical and electrical properties in mind.

Features and properties of VALOX® FR Resin 357

As a mix of PBT and PC materials, VALOX® FR Resin 357 stands out as an unreinforced, impact modified grade with a high level of flame retardancy, outstanding chemical resistance, and a suitability to be processed by injection moulding.

Its flame resistance complies with the UL-94 (V0/5VA/HB) flame rating, which is the standard for safety of flammability of plastic materials for parts in devices and appliances testing. Here’s what each of the mentioned classifications stand for:

  • HB: The lowest UL94 rating; horizontal burn; slow burning and self-extinguishing; burning stops before 100 mm.
  • V0: Vertical burn; burning stops within 10 seconds; drips of particles allowed as long as they are not inflamed.
  • 5VA: The highest UL94 rating; burning stops within 60 seconds; no drips allowed; plaque specimens may not develop a hole.

VALOX® FR Resin 357 has an opaque appearance, with excellent surface finish and a good level of machinability. Combining the benefits of both PBT and PC, VALOX® 357 has great physical and electrical properties, as shown in the table below.

Physical properties

Electrical properties

High chemical resistance

Good dielectric strength

Good machinability

High insulation resistance

Good tensile and yield strength

High arc resistance

High creep and impact resistance

Good electrical resistivity

High dimensional stability


Long-term heat resistance


Low temperature performance (down to -40°C)


High relative thermal index (RTI) up to 140°C


Processing and Applications of VALOX® 357

VALOX® FR Resin 357 is suitable for processing by injection moulding, which is a mass-manufacturing process used to fabricate plastic materials. Simply, molten polymers are injected into a mould, cooled, and then solidified to obtain the required end product. This method is convenient for mass production of plastic parts, even with complicated shapes. The reasons it takes a big part in plastic production include its ability to scale up production, its low cost, low scrap production, and repeatability [3]. VALOX® FR Resin 357, being a thermoplastic material, can be recycled multiple times because thermoplastics can be melted, cooled, solidified, and then melted again without burning.

VALOX® FR Resin 357 is ideal for applications where high chemical resistance and high flame retardancy is required. With its excellent electrical properties, it is typically used for electrical connectors, smart network interface devices (SNID’s), switches, controls, power plugs, and other electrical components. It is also suitable for fibre optic tubes, outdoor telecommunications enclosures, and automotive (under-the-hood) and electrical appliance parts, as in kitchen equipment and consumer goods. VALOX® FR Resin 357 is useful in the medical industry, as well, especially in components such as clamps, plugs, and pump parts.

Other application areas include fluid handling, construction applications, oil/gas applications, and lawn/garden equipment.


[1] “VALOXTM Resin”, SABIC, [Online] Available from: https://www.sabic.com/en/products/polymers/polybutylene-terephthalate-pbt/valox-resin

[2] “Performance featured product guide”, SABIC Innovative PlasticsTM, [Online] Available from: https://www.kmsbearings.com/media/wysiwyg/pdfs/Valox_Resin_guide_by_Sabic_2011.pdf

[3] T. Rogers, “Everything You Need To Know About Injection Molding”, [Online] Available from: https://www.creativemechanisms.com/blog/everything-you-need-to-know-about-injection-molding, 2015.

Quick statistics:

  • Density: 1.34 g/cm³
  • Melt mass-flow rate: 9.6 g/10min
  • Impact strength, Charpy notched: 45 kJ/m²
  • Heat deflection temperature: 138 °C
  • Elongation: 45 % 
  • Water absorption: 0.08 %


Click here for the full technical data sheet (TDS).