PBT GF30: Properties, Datasheet, and Complete Guide to Glass-Filled Polybutylene Terephthalate

What Is PBT GF30?

PBT GF30 is polybutylene terephthalate reinforced with 30% glass fiber by weight. It is one of the most widely specified glass-filled engineering thermoplastics in automotive and electrical applications — and for good reason.

Adding 30% short glass fiber to an unfilled PBT resin more than doubles its tensile strength, quadruples its flexural modulus, and pushes its heat deflection temperature (HDT) from approximately 60°C to above 200°C. These gains make PBT GF30 the default choice whenever designers need a stiff, dimensionally stable polyester that survives underhood temperatures and retains its electrical properties in humid environments.

For procurement teams and design engineers searching for PBT GF30 datasheets, grade comparisons, or supplier alternatives, this page covers the critical data points — mechanical properties, thermal limits, processing parameters, common grades, and how PBT GF30 stacks up against competing materials.

PBT GF30 Typical Properties

The table below consolidates datasheet values from multiple commercial PBT GF30 grades. Exact figures vary by manufacturer and additive package, but these ranges represent what you can expect from a standard 30% glass-filled PBT.

Glass Fiber Content Comparison: PBT GF10 to PBT GF50

PBT is commercially available with glass fiber loadings from 10% to 50%. Each step trades ductility for stiffness, and the sweet spot depends on the application.

Key takeaway: PBT GF30 lands in the center of the cost-performance curve. It delivers roughly 90% of the stiffness of GF50 at a lower price per kilogram and with better moldability. Below GF20, you lose significant HDT and creep resistance. Above GF40, warpage, viscosity, and tool wear become harder to manage.

Common PBT GF30 Commercial Grades

PBT GF30 vs. Competing Materials

PBT GF30 vs. PA66 GF30

When to choose PBT GF30 over PA66 GF30: If your part lives in a humid environment and must hold tight tolerances, PBT wins every time. Electrical connectors, sensor housings, and precision mechanical parts exposed to ambient moisture are textbook PBT territory. PA66 swells — PBT does not.

PBT GF30 vs. PET GF30

PBT and PET are both thermoplastic polyesters, and both benefit from 30% glass reinforcement. PBT crystallizes faster, which translates to shorter molding cycles (a 20–30% productivity advantage in injection molding). PET GF30 pushes HDT slightly higher (225–235°C) and offers better surface gloss, but processes slower and requires higher mold temperatures (120–140°C vs. 60–80°C for PBT). For most injection-molded components, PBT GF30 is the more economical choice.

PBT GF30 vs. PPS GF40

PPS GF40 operates in the 260°C+ continuous-use range, far above PBT’s ceiling. It also provides inherently flame-retardant performance (V-0 without additives). But PPS costs 3–5× more than PBT. Unless your application demands sustained exposure above 180°C, PBT GF30 is the cost-effective route.

Processing Guidelines: Injection Molding PBT GF30

Critical notes for PBT GF30 processing:

• Moisture sensitivity: PBT hydrolyzes at melt temperatures. Anything above 0.02% moisture content will degrade mechanical properties. Dry it — every time.
• Fiber orientation: Glass fibers align with flow direction, creating anisotropic shrinkage. Expect 0.2–0.5% shrinkage parallel to flow and 0.5–1.0% perpendicular. Gate placement matters.
• Desgaste de la herramienta: 30% glass fiber is abrasive. Use hardened tool steel (HRC 54+) or hard chrome plating on mold surfaces.
• Líneas de soldadura: Glass-filled PBT forms visible, mechanically weaker weld lines. Position gates so knit lines occur in non-structural, low-visibility zones.

Key Applications of PBT GF30

Flame Retardant PBT GF30 (V-0 Grades)

Standard PBT GF30 carries a UL94 HB rating. For electrical applications requiring self-extinguishing behavior, a parallel family of PBT GF30 FR V-0 grades exists. These use halogenated or halogen-free flame retardant packages to achieve V-0 at 1.6 mm or thinner.

Notable V-0 grades include:

• BASF Ultradur B4406G6 — halogenated FR, GF30, V-0 at 0.75 mm
• SABIC Valox 420SEO — industry benchmark, GF30 V-0
• Celanex 3316 — GF30, non-halogen FR option available

The trade-off: FR additives typically reduce tensile strength by 5–10% and impact resistance by 15–25% compared to unfilled FR grades. Specify carefully based on whether electrical safety or mechanical load is the primary design constraint.

PBT GF30 vs. Mineral-Filled PBT

Glass-filled PBT is not the only reinforcement option. Mineral-filled PBT (typically MD20–MD40, using talc, calcium carbonate, or wollastonite) delivers lower warpage and better isotropic shrinkage at a lower cost — but sacrifices strength and HDT compared to GF grades.

Choose mineral-filled PBT for large, flat parts where flatness trumps strength — motor end caps, large housings, lighting bezels. Choose PBT GF30 when structural load and thermal resistance matter.

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What does PBT GF30 mean?

PBT GF30 means polybutylene terephthalate (PBT) resin compounded with 30% glass fiber (GF) by weight. The glass fibers are typically short-cut E-glass strands, 3–6 mm in pellet length, that disperse during injection molding to create a stiff, strong composite.

Is PBT GF30 suitable for outdoor use?

Yes — with the right stabilization package. Standard PBT has good inherent UV resistance compared to unfilled nylons, and GF30 grades are commonly used in exterior automotive components (door handles, mirror housings). For prolonged outdoor exposure, specify a UV-stabilized grade such as BASF Ultradur B4300G6 LS (light-stabilized).

Can PBT GF30 be laser-marked?

Yes. PBT responds well to Nd:YAG laser marking. Most GF30 grades produce dark marks on the natural beige/grey base, and laser-markable grades (e.g., BASF B4300G6 LM) are available for high-contrast applications like connector identification.

What is the difference between PBT GF30 and PBT+PET GF30?

PBT+PET GF30 blends combine the faster crystallization of PBT with the higher gloss and slightly better HDT of PET. These blends are common in automotive exterior trim where surface appearance matters and cycle time must stay competitive. Pure PBT GF30 typically offers better chemical resistance.

Does PBT GF30 need to be dried before molding?

Absolutely. PBT is sensitive to hydrolysis at processing temperatures. Material must be dried to below 0.02% moisture content — typically 120°C for 3–4 hours in a desiccant dryer with a dew point of -30°C or lower. Skipping this step will produce brittle parts with degraded tensile and impact properties.

Need PBT GF30 pellets, stock shapes, or machined parts? We supply glass-filled PBT grades from major manufacturers. Contact us with your specification — grade, quantity, and delivery target — and we’ll return a quote.

Last updated: June 2026. Datasheet values are typical ranges; always verify specific grade properties with the manufacturer’s current technical data sheet.