ForMatter/Materials/polymer/Polypropylene Homopolymer (PP)

mat_polypropylene_pp_homopolymer

Polypropylene Homopolymer (PP)

semi-crystalline thermoplastic, polyolefin, fatigue-resistant · PP, polypropylene, homopolymer PP, PP-H

highlast updated 2026-04-27

The cheapest reasonable engineering thermoplastic — yogurt-cup tubs, prescription-pill bottles, automobile bumper covers, the living-hinge box that snaps closed and stays closed for ten thousand openings. Polypropylene's defining trick is that it accepts repeated bending at thin sections without cracking — the integrated-hinge geometry that almost every food-storage container relies on.

Semi-crystalline thermoplastic homopolymer, isotactic stereoregularity standard. Tm ~165 °C, Tg -10 °C. Density 0.905 g/cm³ (the lowest of any common engineering thermoplastic — PP floats in water). Tensile 35 MPa, fatigue endurance limit ~14 MPa over 10⁷ cycles. UV-degrades unless pigmented or stabilized. Joins by ultrasonic welding cleanly; surface energy too low for most adhesives without flame or corona pretreatment.

Mechanical

tensile strength · MPa35
yield strength · MPa33
elastic modulus · GPa1.5
elongation (at break) · %600
density · kg/m³905

source: MakeItFrom; SABIC PP datasheet

Thermal

melting point · °C165
service max · °C100

source: SABIC datasheet

Sustainability

embodied carbon · kg CO₂e/kg2.0
embodied carbon recycled · kg CO₂e/kg0.5
recyclabilityhigh — RIC #5 stream, mature secondary processing
biodegradableFalse
certificationsFDA 21 CFR 177.1520 (food contact)

source: Editorial estimate from ICE / Granta CES EduPack class databases — industry mean, with cradle-to-gate boundary unless otherwise noted. Embodied carbon for any specific product depends on supplier mix, recycled content, and energy grid; verify against a primary source before using these numbers in a sustainability claim.

visual: natural translucent off-white; pigments easily; slight waxy gloss on injection-molded surface
tactile: warm to the touch (low thermal conductivity), waxy, light

Ed Conway (living — quote)

There is polypropylene, flexible enough to be used as the lid of a flip-top bottle but hard enough to be formed into furniture.

Conway, Material World: The Six Raw Materials That Shape Modern Civilization (Knopf, 2023), Part Two: Salt / Oil, 'Plastic Planet' chapter. Conway's compressed sketch of PP comes inside the broader argument that polyethylene was 'the most important synthetic material in the world' and that PP is one of the five main families of human-made polymer that bookend the Second World War. The two ends Conway names — flip-top-bottle living-hinge at one end, injection-molded furniture (the Monobloc, the Robin Day chair) at the other — are precisely the two ends ForMatter's PP entry has to cover. Ed Conway (b. 1979) is Economics Editor of Sky News; verified living 2026-04-28.

PBR starter values

finish · matte — open for table, JSON, host snippets, downloads

Principled BSDF defaults derived from the sphere matte finish. Reasonable seed for Blender, Substance, Keyshot, Rhino — tune per material. Or grab the whole library at once: ForMaterials library →

# finish:                   matte
albedo                      #3c3c3c
metallic                    0.00
roughness                   0.75
ior                         1.45
transmission                0.00
clearcoat                   0.00
sheen                       0.00
anisotropic                 0.00

copy as JSON

{
  "albedo": "#3c3c3c",
  "metallic": 0.0,
  "roughness": 0.75,
  "ior": 1.45,
  "transmission": 0.0,
  "clearcoat": 0.0,
  "sheen": 0.0,
  "anisotropic": 0.0
}

Blender 4.x Python

# Blender 4.x — Principled BSDF
# Polypropylene Homopolymer (PP) · finish: matte
import bpy
mat = bpy.data.materials.new(name="mat_polypropylene_pp_homopolymer")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value         = (0.0452, 0.0452, 0.0452, 1.0)
bsdf.inputs["Metallic"].default_value           = 0.000
bsdf.inputs["Roughness"].default_value          = 0.750
bsdf.inputs["IOR"].default_value                = 1.450
bsdf.inputs["Transmission Weight"].default_value = 0.000
bsdf.inputs["Coat Weight"].default_value        = 0.000
bsdf.inputs["Sheen Weight"].default_value       = 0.000
bsdf.inputs["Anisotropic"].default_value        = 0.000

KeyShot Python (lux)

# KeyShot 11+ — lux Python API, Generic material
# Polypropylene Homopolymer (PP) · finish: matte
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_polypropylene_pp_homopolymer", materialType="Generic")
mat.setProperty("diffuse",      (60, 60, 60))   # 8-bit sRGB
mat.setProperty("metallic",     0.000)
mat.setProperty("roughness",    0.750)
mat.setProperty("indexOfRefraction", 1.450)
mat.setProperty("transparency", 0.000)
mat.setProperty("coatingWeight", 0.000)

Substance pbrMetalRough

{
  "_format": "Substance Designer / Painter \u2014 pbrMetalRough constants",
  "_about": "Polypropylene Homopolymer (PP) \u00b7 finish: matte",
  "baseColor": {
    "r": 0.0452,
    "g": 0.0452,
    "b": 0.0452
  },
  "metallic": 0.0,
  "roughness": 0.75,
  "ior": 1.45,
  "opacity": 1.0,
  "anisotropyLevel": 0.0,
  "_notes": "Channels listed are the standard Substance pbrMetalRough output. Drop into a Uniform Color node per channel, or as the constant input on a layered stack."
}

glTF 2.0 Metallic-Roughness

{
  "asset": {
    "version": "2.0",
    "generator": "ForMatter"
  },
  "materials": [
    {
      "name": "mat_polypropylene_pp_homopolymer",
      "pbrMetallicRoughness": {
        "baseColorFactor": [
          0.0452,
          0.0452,
          0.0452,
          1.0
        ],
        "metallicFactor": 0.0,
        "roughnessFactor": 0.75
      },
      "extensions": {
        "KHR_materials_ior": {
          "ior": 1.45
        }
      }
    }
  ]
}

USD Preview Surface

# USD Preview Surface — UsdShade.MaterialLook prim attributes
# Polypropylene Homopolymer (PP) · finish: matte
def Material "mat_polypropylene_pp_homopolymer" {
    token outputs:surface.connect = </mat_polypropylene_pp_homopolymer/PreviewSurface.outputs:surface>

    def Shader "PreviewSurface" {
        uniform token info:id = "UsdPreviewSurface"
        color3f inputs:diffuseColor = (0.0452, 0.0452, 0.0452)
        float   inputs:metallic     = 0.000
        float   inputs:roughness    = 0.750
        float   inputs:ior          = 1.450
        float   inputs:opacity      = 1.000
        float   inputs:clearcoat    = 0.000
        token   outputs:surface
    }
}

↓ download glTF material

CNC milling on swarf

surface speed (carbide)800–1500

chipload per tooth5–10 (1/4-inch O-flute endmill)

coolantair blast for chip evacuation

swarf-compatible toolsend 1/8end 1/4end 3/8drill 1/8drill 1/4

PP machines easier than HDPE — slightly stiffer chip, less stringy. The Monobloc-chair material; also the canonical living-hinge polymer. Use O-flute endmills for clean cuts on the bench-tier swarf machines.

Onsrud Cutter plastic feeds & speeds (PP table); SABIC polypropylene sheet-machining guide.

→ try this material in swarf

ProcessInjection Molding · Extrusion · Vacuum Forming (Thermoforming)

Used inFood Packaging · Consumer-Electronics Enclosure

Substitutes

High-Density Polyethylene (HDPE)

ABS (Acrylonitrile Butadiene Styrene)

Second life

repairabilitymoderate — thermally weldable; living-hinge geometry rated for 10,000+ cycles before fatigue cracks form.

recyclabilitygood — RIC code 5; mature secondary processing; the Monobloc chair is recycled at >50% rates in EU markets.

disposal pathcurbside recycling where #5 is accepted (most US programs since ~2015).

typical longevity15 years (typical)

failure modes

UV degradation without stabilizer (the Monobloc-chair failure mode — left in sun for years, the chair embrittles and snaps)
living-hinge fatigue past design cycle count
oxidative degradation at elevated temperatures

SPI / PLASTICS recycling guide (RIC 5); SABIC polypropylene technical literature.

In the collection

V&A
Polypropylene Chair (Mark II) by Robin Day · 1964
Injection-molded polypropylene shell on metal base, made by S. Hille & Co. A single tool produced 4,000 shells weekly, ninety seconds per shell.

Citations

en.wikipedia.org — Polypropylene
book · Lefteri, Materials for Design (Laurence King, 2014), polypropylene spread.
book · Bürdek, Design: History, Theory and Practice of Product Design, 2nd revised English ed. (Birkhäuser, 2015), 'Semiotics and Design' — the Monobloc plastic chair (one billion units in existence, single-shot injection-molded PP, the canonical mass-democratic chair) is the limit case for PP as a material; verbatim quote on app_chair.

Concordance

House vocabulary — terms ForMatter uses with intent.

anisotropic: Direction-dependent. Wood reads differently along the grain than across it; rolled steel is stiffer along the rolling direction. The Principled-BSDF anisotropic input rotates the highlight to match.
anodize: Electrochemical oxide layer grown on aluminum (Type II / III), titanium, or niobium. Type II accepts dye for color; titanium / niobium use voltage-driven thin-film interference instead of dye. The CMF entry covers the seal step that locks the color in.
application: What the thing IS, in the world. The third entity, peer of material and process. A water bottle, a chair, an extruded-aluminum profile.
BRDF: Bidirectional Reflectance Distribution Function. The math behind how a surface returns light for any incoming and outgoing direction. The PBR model is a parameterized BRDF.
channeled: A voice block written within a dead author's philosophy, marked and cited. Distinct from a verbatim quote. Roland Barthes channeled on PMMA reads like Barthes; the citation attributes the lineage.
CMF: Color, Material, Finish — the trio designers specify together when handing a part off for production. ForMatter's Finish entity is the F in CMF: 10 categories — polish / anodize / patina / plate / coating / texture / cut / mold_finish / glaze / stone_finish — and entries under each. Every finish entry pairs to the materials and processes it suits.
choral fugue: ForMatter's register. Subject stated plainly (freshman tier), answered in technical and sensorial registers, countersubjects from linked processes and applications, citations as final stretto. Voice blocks where canon attaches.
clearcoat: A second specular layer over the base surface. Glossy plastics and lacquered woods get a clearcoat term in the PBR table. IOR 1.5 by default.
compatibility (process): Each process entry lists which materials it can work. The cross-ref renders as sphere pills so the gallery feeling extends inward.
confidence: Each entry tagged high / medium / low. A senior's low-confidence-with-three-citations beats a freshman's high-confidence-with-none. The label is a contract with the reader, not a brag.
crystalline (finish): A faceted-surface read — gemstones, glassy minerals, ice. Drives PBR defaults: IOR 2.42 (diamond), transmission 1.0, low roughness.
derive_pbr(): The build's single source of truth — sphere palette + finish enum → Principled-BSDF starter values. One function feeds the entry-page table, the per-host snippets, the glTF export, and the Three.js Live Preview.
finish (entity): ForMatter's CMF layer — surface treatments and conditions a designer chooses for a given material and process. Categories: polish, anodize, patina, plate, coating, texture, cut, mold_finish, glaze, stone_finish. Distinct from the sphere `finish` enum (metallic / matte / glossy / etc.) which is the visual register of the proxy.
freshman / senior register: Two registers in every entry — the plain freshman description and the technical / sensorial one. Same database, two readers, no extra subscription.
glTF: GL Transmission Format — the open 3D-asset standard every modern app reads. ForMatter emits a .gltf material doc per material. Open standard, designer-friendly handoff.
IOR: Index of Refraction. How much light bends entering the surface. Air 1.0, water 1.33, glass 1.5, diamond 2.42. Drives transmission and the specular term.
iridescent (finish): Hue-shifted accent over base. Anodized titanium and niobium, opal, paraíba. Drives PBR defaults: low metalness, full iridescence, clearcoat.
iridescence: Thin-film interference layer over the base material. KHR_materials_iridescence in glTF, MeshPhysicalMaterial.iridescence in Three.js. Tunable from the FOCUS slider on iridescent / pearlescent entries. The ior and thickness range together set the visible color sweep — opal uses a 100–800 nm thickness range (film, not wavelength) to span the full visible band.
lite-PBR: ForMatter's PBR approach — Principled-BSDF starter values per entry, no measured BRDFs, no commercial assets. Reasonable defaults from the finish enum, per-entry numeric overrides where you have a real reason.
Live Preview: The Three.js shader ball that replaces the static CSS sphere on every entry page. One render path for every category — metals, woods, polymers, ceramics, paints, textiles, gemstones, glass. Same derive_pbr() values, real-time lit by a synthetic studio environment, draggable. Optional — toggle in Preferences.
material: What the thing is MADE OF. The first entity. Aluminum 6061, white oak, soda-lime glass.
metallic (finish): Specular highlight, deep shadow rim. Drives PBR defaults: metalness 1, low roughness, IOR 1.45. Polished steel, gold, copper.
mood board: Folded into the Project workspace at /project.html. The mood-board upload, palette extraction, character chips, and matcher results all live alongside the collected items grid and the save .formatter / save PDF / open .formatter actions — one feature, one page.
Ollama: Local-LLM scaffold on the Project page. Off by default. When toggled on in Preferences AND Ollama is reachable at localhost:11434, the natural-language input box ('something soft and warm with a wet read') asks the model to translate the description into character-chip toggles. Never invents material properties; the LLM only translates intent into existing chip vocabulary. The keyword fast-path (chips alone, no LLM) is the default — see suite-wide ai-integration pattern.
project: The full workspace at /project.html — collected materials, processes, applications, finishes plus an optional mood-board image whose dominant colors search the library for matches. Save / open .formatter files round-trip the project state.
patina: A chemical color shift on metal — heat-blue on steel, fume-black on silver, verdigris on copper, gun-blue on tool steel, ferric on copper. CMF-layer entry; cited by both the material and the process pages that produce it.
PBR: Physically-Based Rendering. The shading model every modern 3D app uses, parameterized by metallic / roughness / IOR / transmission / clearcoat / sheen. ForMatter publishes starter values for every material entry.
SPI mold finish: Society of the Plastics Industry mold-cavity finish standard. A1 / A2 / A3 (diamond polish, mirror), B1 / B2 / B3 (paper, semi-gloss), C1 / C2 / C3 (stone, matte), D1 / D2 / D3 (dry blast, textured). The finish prints from the mold cavity onto the molded part — a designer picks the SPI grade with the molder when specifying the tool.
Principled BSDF: Blender's name for the consolidated PBR shader. Most other apps ship the same shader under different names (Standard Surface, ShaderGraph, Substance). One node, every output.
process: How the material is MADE INTO the thing. The second entity. Cast, machined, kerf-bent, anodized, planished, granulated. Process is a peer of material, not a footnote.
quote: A voice block carrying a verbatim quotation from a living author, with citation. Distinct from a channeled block. Living = quote only; the rule is enforced at the schema layer.
roughness: Microsurface scatter. 0 is mirror-smooth; 1 is fully diffuse. Most real surfaces sit between 0.2 and 0.8.
sphere proxy: ForMatter's visible-character stand-in for every material. CSS-gradient driven by the entry's palette and finish, not a baked render. Honest about being a proxy, scales cheaply, tweakable in one place.
substitute: A peer material that could fill a similar role. Cross-references render as sphere pills inside an entry — the gallery feeling extends inward.
transmission: How much light passes through. 1 is fully transparent; 0 is opaque. Glass, gemstones, clear plastics carry transmission.
PVD: Physical Vapor Deposition — vacuum-chamber sputter or cathodic-arc deposition of a thin ceramic film onto a metal substrate. The CMF-layer's modern coating chemistry: TiN (gold), ZrN (champagne), CrN (pewter), TiCN (warm bronze / rose-gold), AlTiN (charcoal-anthracite, near-black), DLC (deep black). Hard, doesn't tarnish, paint-thin.
VDI 3400: German engineering reference standard for mold-cavity texture (Erodieren bearbeitete Werkstückoberflächen). The full scale runs reference plates 0–45 by Ra value; production specs typically draw from 12–45 because plates 0–11 require diamond-mirror polish on the mold cavity and are rarely commissioned in commercial tooling. Pairs with the SPI standard; both define what gets cut into the mold.
voice block: A versal block where a real authored voice attaches to the material or process. Schema-tagged with status (living / dead) and mode (quote / channeled). Citations always.
woodgrain (finish): Directional sheen with grain ring. Drives PBR defaults: anisotropic 0.6, medium roughness, no metalness. Every wood entry.

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Polypropylene Homopolymer (PP)

Mechanical

Thermal

Sustainability

PBR starter values

CNC milling on swarf

Second life

In the collection

Citations

Concordance

ForMatter

Why this exists

Sources

Rules of the house

Sister apps

Preferences