PP
also Hostalen PP, Pro-fax
PP is a low-density semi-crystalline polyolefin made by catalytic polymerization of propylene, supplied as homopolymer (stiffer, higher Tm), impact/block copolymer (tough down to −30 °C) and random copolymer (clearer, lower Tm).
PP grades and fills
PP is supplied in 12 conditions, soft to hard.
Compare all 12 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Expanded polypropylene bead foam | Multi-impact energy absorbing foam for automotive bumper cores, head-impact pads and reusable packaging. | 0.8 | 15 | ||
FFF/FDM 3D-printed PP | Use for chemically resistant, living-hinge or fatigue-flexing printed parts; expect anisotropy, low layer adhesion and severe warping without PP build surface. | 22 | 15 | ||
pipe / clarified grade | For hot/cold water pipe and fittings and for clearer thin-wall packaging; softer, lower Tm, better clarity and weld strength. | 25 | 26 | 500 | |
Flame retardant, UL 94 V-0 | Halogen-free or brominated FR compound for electrical housings, battery boxes and appliance parts needing V-0. | 25 | 25 | 20 | 73 Shore D |
Recycled PP | Lowest-cost / lowest-carbon option for non-critical parts; expect batch-to-batch variation in colour, MFR and impact. | 25 | 26 | 60 | 68 Shore D |
Impact (block) copolymer PP-B | Pick when toughness below 0 °C matters — automotive interior parts, crates, battery cases, cold-store containers. | 26 | 27 | 400 | 68 Shore D |
Talc filled (typ. 20%, range 10–40%) | Cheap stiffness, lower shrinkage/warpage and better dimensional stability and scratch feel; used for automotive trim, appliance and packaging parts. | 29 | 30 | 20 | |
general-purpose unfilled injection/extrusion grade | Generic commodity PP when the datasheet does not distinguish homo- from copolymer; safe average design values. | 30 | 32 | 200 | 70 Shore D |
10% glass-fiber reinforced | Small stiffness/HDT boost with minimal warpage and cost penalty; light structural brackets. | 45 | 6 | ||
20% glass-fiber reinforced | Balanced stiffness/toughness/cost for pump housings, fan shrouds and appliance structures. | 65 | 4 | ||
30% glass-fiber reinforced | Workhorse structural PP: highest strength/stiffness per cost for under-hood, pump and HVAC parts to ~130 °C. | 85 | 3 | 45 HRM | |
40% glass-fiber reinforced | Maximum stiffness/strength PP compound where metal replacement and dimensional stability outrank toughness and surface finish. | 100 | 2.5 |
Supply forms, finishes and certifications
Ways PP is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
UV Stabilized | UV / weather stabilized | Grade option |
HomopolymerDefault | Homopolymer | Standard supply |
What is PP?
PP is a low-density semi-crystalline polyolefin made by catalytic polymerization of propylene, supplied as homopolymer (stiffer, higher Tm), impact/block copolymer (tough down to −30 °C) and random copolymer (clearer, lower Tm). It is chosen for its very low cost and density, outstanding resistance to water, acids, alkalis and most polar solvents, excellent living-hinge fatigue life and easy injection molding and hot-gas/extrusion welding. Main limits are poor UV and oxidation resistance without stabilizers, brittleness near and below 0 °C for homopolymer, high mold shrinkage and warpage, very low surface energy (needs corona/flame treatment for bonding or paint), and creep above ~80 °C. PP has a density of 0.91 g/cm³ (0.0327 lb/in³), lighter than 81% of polymer grades. Its glass-transition temperature is -10°C (14 °F). PP has a yield strength of 33 MPa (4.79 ksi) and a tensile strength of 35 MPa (5.08 ksi) — weaker than 68% of polymer grades. Elongation at break is 150% and the elastic modulus is 1.5 GPa (0.218 Msi).
What is PP used for?
- Chemical storage tanks and liners
- Food packaging containers and closures
- Living-hinge lids and boxes
- Pipe and fittings for corrosive fluids
- Automotive interior trim and battery cases
- Laboratory labware and trays
- Filter housings and pump components
Advantages
- Readily welded — 92/100, better than 97% of polymer grades
- Low embodied carbon — 2 kg CO₂/kg, better than 96% of polymer grades
- Low moisture uptake — 0.02%, better than 92% of polymer grades
- Good corrosion resistance — 92/100, better than 91% of polymer grades
- Tough — resists crack growth — 3.5 MPa·√m (3.19 ksi·√in), better than 81% of polymer grades
Limitations
- Degrades in UV without stabilisers — 20/100, worse than 88% of polymer grades
PP properties
Typical room-temperature values in the Homopolymer condition; bars are the position among polymer grades.
Physical6
PP has a density of 0.91 g/cm³ (0.0327 lb/in³), lighter than 81% of polymer grades. Its glass-transition temperature is -10°C (14 °F).
Mechanical16
PP has a yield strength of 33 MPa (4.79 ksi) and a tensile strength of 35 MPa (5.08 ksi) — weaker than 68% of polymer grades. Elongation at break is 150% and the elastic modulus is 1.5 GPa (0.218 Msi).
Thermal11
PP is rated for continuous service to 100°C (212 °F). It conducts heat at 0.22 W/m·K (0.127 BTU/hr·ft·°F), better than 60% of polymer grades. Thermal expansion is 110 µm/m·K (61.1 µin/in·°F).
Electrical7
PP is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (92/100), better than 91% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of PP takes about 78 MJ of energy and emits 2 kg of CO₂ — less than 88% of polymer grades. Typical recycled content is 5%.
Manufacturability8
PP's machinability is good (60/100, better than 51% of polymer grades); weldability excellent (92/100); formability very good (80/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polymer family
Yield strength against density for every polymer grade FabDigit runs. PP is highlighted; hover a dot for its name, or open the interactive family chart.
Working with PP
Is PP easy to machine?
Machines easily but is soft and gummy — use sharp, high-rake tools, high speed with low feed pressure, air blast cooling, and generous support to control springback; annealed stock reduces post-machining distortion.
Can PP be welded?
Excellent hot-gas, extrusion, butt-fusion, socket-fusion, ultrasonic, vibration and spin welding with PP filler; no solvent cementing exists — adhesive bonding needs flame/corona/plasma pretreatment or polyolefin primer.
Can PP be formed, bent or molded?
Injection molds at 200–260 °C melt / 20–60 °C tool; shrinkage is high (1.2–2.2%) and crystallization-driven, so allow for post-mold shrink and warp, use uniform walls, and thermoform sheet in the narrow 150–165 °C window.
Manufacturability
The process limits FabDigit's quote engine applies to PP. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Better60 / 100 |
|---|---|
| ISO material group | N.8 |
| Cutting speed (rough / finish) | 400 / 500 m/min |
| Minimum wall | 0.5 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 10× diameter |
| Best surface (machined / polished) | Ra 0.8 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better80 / 100 |
|---|---|
| Weldability | Fair92 / 100 |
Injection molding
| Mold shrinkage | — |
|---|---|
| Wall thickness | — – — |
| Recommended draft | — |
| Pre-drying | — |
3D printing
| Technologies | MJF, FDM |
|---|---|
| Layer height | 50 – 300 µmdefault 100 µm |
| Minimum wall / feature | 1 / 0.5 mm |
| Build envelope | 300 × 300 × 380 mm |
| Supports | Yes |
| Anisotropy | Moderate |
PP chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| ethylene comonomer2–7% in random copolymer (PP-R), 5–15% EPR phase in impact copolymer | 0 – 12 | 0 |
| antioxidant / process stabilizerhindered phenol + phosphite | 0.05 – 0.5 | 0.2 |
| nucleating agent / acid scavengerCa-stearate, sorbitol clarifier | 0 – 0.3 | 0.1 |
| glass fiberGF10–GF40 variants, MAH-PP coupled | 0 – 40 | 0 |
| talc / CaCO3 fillermineral-filled variants | 0 – 40 | 0 |
| propylene repeat unit (C3H6)isotactic polypropylene backbone; copolymer grades contain ethylene comonomer | ≥ 92 (balance) |
What surface finishes work on PP?
Cannot be electroplated or anodized; paint and print only after flame/corona/plasma treatment with adhesion promoter, otherwise use in-mold texture, mass coloring or laser marking.
Surface treatments FabDigit runs on polymer parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Coating
Injection Molding Coating
Organic Coating
Metallization / Functional
Coloring
Equivalent designations
Standards and trade names that resolve to PP in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Hostalen PPPro-faxPP Filament
- Also called
- Polypropylene
How much does PP cost?
PP is a budget-cost polymer ($), cheaper than about 99% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
PP — frequently asked
What is PP used for?
PP is typically used for chemical storage tanks and liners, food packaging containers and closures, living-hinge lids and boxes, pipe and fittings for corrosive fluids, automotive interior trim and battery cases and laboratory labware and trays. In short: rigid; standard plastic.
What is the yield strength of PP?
PP has a typical yield strength of 33 MPa (4.79 ksi) and a tensile strength of 35 MPa (5.08 ksi) — weaker than 68% of polymer grades. Strength varies by condition: see the 12 listed tempers.
Is PP easy to machine?
Reasonably — machinability is rated good (60/100, better than 51% of polymer grades). Machines easily but is soft and gummy — use sharp, high-rake tools, high speed with low feed pressure, air blast cooling, and generous support to control springback; annealed stock reduces post-machining distortion.
Can PP be welded?
Yes — weldability is rated excellent (92/100). Excellent hot-gas, extrusion, butt-fusion, socket-fusion, ultrasonic, vibration and spin welding with PP filler; no solvent cementing exists — adhesive bonding needs flame/corona/plasma pretreatment or polyolefin primer.
What surface finishes work on PP?
Cannot be electroplated or anodized; paint and print only after flame/corona/plasma treatment with adhesion promoter, otherwise use in-mold texture, mass coloring or laser marking.
Can PP be formed, bent or molded?
Injection molds at 200–260 °C melt / 20–60 °C tool; shrinkage is high (1.2–2.2%) and crystallization-driven, so allow for post-mold shrink and warp, use uniform walls, and thermoform sheet in the narrow 150–165 °C window.
What is the maximum service temperature of PP?
PP is rated for continuous use to about 100°C (212 °F), and briefly to 130°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does PP cost?
PP is a budget-cost polymer ($), cheaper than about 99% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in PP?
Yes — PP is available for CNC machining, sheet metal, injection molding and 3D printing with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM D4101 – Standard Classification for Polypropylene Injection and Extrusion Materials — ASTM International (2023)
- ISO 19069-1/-2 – Plastics: Polypropylene (PP) moulding and extrusion materials — ISO (2019)
- GB/T 2546.1 / GB/T 12670 (PP) — SAC (2018)
- Moplen / Pro-fax / Hostacom PP grade datasheets — LyondellBasell (2023)
- Borealis / Borouge PP homopolymer and copolymer datasheets — Borealis (2023)
- CAMPUS plastics database – PP entries (ISO 10350 property set) — CWFG / CAMPUS consortium (2024)
- Engineered Materials Handbook Vol.2: Engineering Plastics — ASM International (1988)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.