Talc filled polypropylene: 10% to 40% talc PP for appliance, automotive and industrial parts

Talc levels compared

The values below come from published data sheets for talc-filled homopolymer compounds, tested to ASTM methods. They show how properties move as talc rises. Copolymer-based grades are less stiff and tougher at each level. Unfilled values are from our polypropylene page.

Typical values from individual compounder data sheets (tangent modulus for the filled rows unless noted); grades vary with the talc grade, base resin and additives. Where only one sheet listed a value, we say so. These fall inside the about 2–4 GPa flexural modulus window on our PP grade finder for 20–40% filled grades. Confirm against the data sheet for the exact grade.

Homopolymer or copolymer base

• Homopolymer base. The stiffest and highest-heat option at each talc level. Use it for appliance tubs and housings, brackets and parts that see heat but are not dropped cold. Like unfilled homopolymer, it turns brittle near 0°C / 32°F.
• Impact copolymer base. Lower stiffness and heat deflection, but much better impact, including in the cold. Use it for parts that get dropped, struck or used in a freezer or a winter car.
• Copolymer plus elastomer and talc (TPO). Automotive interior trim, instrument panels and some exterior parts use impact copolymer blended with an elastomer and talc to balance stiffness, cold impact and paintability or scratch resistance. See PP homopolymer vs. impact copolymer.
• What to send. If you are not sure which base you run, send the data sheet. The flexural modulus and notched Izod, read together, often tell a chemist which base it is.

What talc does for a PP part

• Stiffness. Talc is a plate-shaped mineral. The plates line up with flow and stiffen the part, so flexural modulus climbs steadily from 10% to 40%.
• Heat deflection. HDT at 0.45 MPa / 66 psi rises from about 80–105°C / 176–221°F unfilled to about 132–143°C / 270–290°F at 40% in published grades, so parts hold shape near heaters, motors and hot water.
• Shrink and warp. Talc cuts shrinkage and makes it more even than glass fiber does. Our processing chart lists about 1.10–1.50% at 20% talc and 0.70–1.00% at 40%, against 0.8–2.5% unfilled homopolymer. Compounder data sheets vary: one series lists 1.1–1.5% at 20% and 0.7–1.1% at 40%, another about 1.3–1.7% and 1.1–1.5% (both ASTM D955, 3.2 mm / 0.125 in). Use the value for your grade and part. See warped parts.
• Faster setup in the mold. Talc also nucleates PP, which can raise the crystallization temperature and shorten cooling. Switching between talc grades can change cycle time.
• Cost. Talc PP is one of the lowest-cost ways to make PP stiffer and flatter. It costs far less to stiffen a part with talc than with glass, which is why it is the default for large appliance and interior parts that do not carry structural loads.
• Surface hardness. Talc raises surface hardness and stiffness, but that is not the same as scratch resistance. Scratches on talc PP can whiten, so interior parts need a scratch package (see below).

What talc costs you

• Weight. Talc is about three times as dense as PP. A 40% talc grade weighs about 35–40% more per part than unfilled PP, and at higher talc levels the saving is cost, not weight. See making a part lighter.
• Impact. Room-temperature notched Izod on homopolymer grades stays low, about 0.5–0.7 ft-lb/in (about 27–37 J/m) in published 20% and 40% grades, lowest at 40%, while falling-weight impact drops as talc rises: one series lists 8 in-lb at 20% and 2–6 in-lb at 40% (Gardner, ASTM D5420). Copolymer grades lose more of their toughness as talc goes up.
• Appearance. Talc PP is off-white to gray in natural, so bright whites and clean pastels are harder than with unfilled PP or calcium carbonate. Talc can also lower gloss and make weld lines more visible.
• Tiger stripes. Alternating glossy and dull bands across the flow, most often on long flow paths in talc-filled, rubber-modified PP. Injection speed is a major factor. Some grades are formulated to resist it. See flow lines and flow marks.
• Scratch whitening. Talc particles scatter light at a scratch, so scratches show more on talc-filled interior parts unless the grade has a scratch package or surface-treated talc.
• Heat aging. Talc can shorten long-term heat aging, and the talc source matters, so talc grades for heat-exposed parts often carry a stronger stabilizer package. Ask for oven-aging data for parts near heaters, motors or hot water.

Talc vs. calcium carbonate and other minerals

General comparison. Filler grade, particle size and surface treatment change the result as much as the filler type.

Ash, melt flow and the COA

Calcium carbonate breaks down to lime and carbon dioxide if the furnace runs hot enough, so its ash can read low unless the method accounts for it. Agree the ash method and temperature with the supplier, and see the incoming inspection checklist.

Where talc filled PP is used

Typical uses only. Your part, its load and its approvals decide the grade.

UV, scratch, color, odor and flame packages

• UV. Outdoor and sunlit parts need a UV-stabilized talc grade. Ask for weathering data on the talc compound itself, not on the unfilled base resin. See fading, yellowing or chalking.
• Scratch. Interior grades add slip agents, siloxane masterbatch or surface-treated talc to cut scratch whitening. Some slip agents wipe off or bloom over time. Ask which OEM scratch test the grade has passed.
• Color. Natural talc PP is off-white to gray, so most talc parts are black, gray or a darker color. Ask for color on the compound, not a let-down of concentrate into natural talc PP, if the color match is tight. See masterbatch vs. precolored resin.
• Odor and emissions. Cabin parts and appliance parts that touch food or water often need low-odor grades. Recycled-content talc PP can carry more odor, so ask for odor data or a sample.
• Flame retardant. Talc grades are rated UL 94 HB in many cases. For V-2 or V-0, see flame-retardant polypropylene; the listing belongs to the exact grade, color and thickness.
• Drying. Unfilled PP does not need it. Filled PP can pick up surface moisture, so dry at about 75°C / 167°F for 2 hours if parts show splay or the resin sat damp, per our drying chart.

What to put on the RFQ, and how it is priced

Talc PP is a compound, so its price does not track the PP index one for one. Base resin, talc grade and level, compounding, color and additive packages all sit on top. Talc lowers the resin share per pound, but the part gets heavier, so compare cost per part, not only cost per pound. We do not post prices. We quote a specific grade, quantity, package and ship-to city, from one gaylord (about 1,000 to 1,600 lb) to truckloads, and every prime lot from our suppliers ships with a COA.

• The grade you run now, or the material callout from the drawing, such as PP-T20 or PP-T40. Our material code decoder reads those.
• Talc level and tolerance, with ash by ASTM D5630 or ISO 3451-1 on every lot COA.
• Base resin. Homopolymer, impact copolymer or TPO.
• Melt flow, at 230°C / 446°F, 2.16 kg, with the range you can run.
• Additive package. Heat-stabilized, UV-stabilized, scratch-resistant, low-odor, flame-retardant, as needed.
• Color. Black, natural or a color match.
• Approvals. OEM spec, UL listing, or appliance maker's approved list.
• Quantity and ship-to. This order, yearly use and the city.

Common questions

If your grade is not listed, tell us what you run. We source commodity, engineering and specialty resins.