Thermoplastic Elastomers (TPE, TPU, TPV): Microphase Separation, Properties & Processing

Thermoplastic elastomers (TPEs) bridge rubber and thermoplastics — rubber-like at service temp, processable like thermoplastics. They eliminate vulcanisation, reduce scrap, and enable recycling. Kraton India, Polyman (Chennai), and PolyOne (Avient, Mumbai) supply TPE/TPU for automotive seals, medical devices, footwear, and consumer goods. Bata India, Hero MotoCorp, and Maruti Suzuki are major end-users.

• Explain microphase separation and its role in TPE elastomeric behaviour.
• Distinguish SBS/SEBS, TPU, TPV, and TPO by structure and performance.
• Calculate compression set from ASTM D395 data.
• Select TPE grade for a given application (temperature, oil resistance, compression set).
• Identify ISO 37 (tensile), ASTM D2240 (hardness), ASTM D395 (compression set).

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  "primitiveId": "primitive-pyrolysis-recycling",
  "title": "Thermoplastic Elastomers (TPE, TPU, TPV): Microphase Separation, Properties & Processing — Mechanism & Physics Diagram"
}

3.1 Microphase Separation

TPEs have hard segments (crystalline/glassy — physical crosslinks) and soft segments (amorphous rubbery — elasticity). Nanoscale phase separation (10-30 nm) creates the dual network. Heating dissolves hard domains → thermoplastic flow; cooling reforms them → rubber elasticity returns.

3.2 TPE Families

3.3 Compression Set — ASTM D395

\text{CS (%)} = \frac{t_0 - t_r}{t_0 - t_s} \times 100 Where: t₀=original, t_r=recovered, t_s=compressed thickness.

{
  "title": "Thermoplastic Elastomers (TPE, TPU, TPV): Microphase Separation, Properties & Processing — Industrial Process Flow Diagram (PFD)",
  "subtitle": "ISO 10628 Unit Operations & Thermodynamic Control Sequence",
  "steps": [
    { "step": 1, "title": "Raw Material Feed & Metering", "description": "Drying to < 0.02% moisture and gravimetric dosing", "parameters": "80°C - 100°C", "output": "Conditioned Feed" },
    { "step": 2, "title": "Reaction & Polymer Melt Processing", "description": "Controlled thermal shear dissipation and phase transition", "parameters": "220°C - 260°C", "output": "Homogenous Melt" },
    { "step": 3, "title": "Shaping & Solidification", "description": "Die extrusion or mold cavity pressure packing", "parameters": "60 - 120 bar", "output": "Formed Component" },
    { "step": 4, "title": "Quality Inspection & Testing", "description": "ASTM D638 / ISO 527 tensile & MFI compliance check", "parameters": "QA Passed", "output": "Finished Grade" }
  ],
  "recycleLoop": "Closed-loop sprues and edge-trim regrind re-fed into main hopper at maximum 15% blend ratio.",
  "notes": "Standard Indian Industrial Practice (CIPET / Reliance / Supreme Petrochem Protocol)"
}

A TPV seal: t₀=4.0mm, t_s=3.0mm, t_r=3.5mm after 70h/70°C. CS = \frac{4.0-3.5}{4.0-3.0}\times100 = 50% Result: CS=50% exceeds typical automotive spec of <40%. Reformulate with higher vulcanisation degree.

{
  "title": "Thermoplastic Elastomers (TPE, TPU, TPV): Microphase Separation, Properties & Processing — CAD Tooling & Machine Geometry Blueprint",
  "drawingNumber": "DWG-POLY-2026-860",
  "scale": "1:1 (FULL)",
  "material": "P20 Tool Steel / Hardened Alloy (HRC 48-52)",
  "dimensions": [
    { "label": "Primary Processing Tolerance", "value": "± 0.02 mm", "tolerance": "ISO 20457 Class M1" },
    { "label": "Thermal Expansion Allowance", "value": "1.5%", "tolerance": "Volumetric Shrinkage" },
    { "label": "Draft Angle Minimum", "value": "1.0° - 1.5°", "tolerance": "Core/Cavity Ejection" }
  ],
  "notes": [
    "Fabricated according to ISO 20457 plastic molding tolerance standards.",
    "EDM finish SPI C-1 applied across cavity optical contact faces.",
    "Conformal cooling lines pressure tested at 12 bar water flow."
  ]
}

Polyman Composites (Chennai) compounds SEBS for Bata India footwear achieving UV stability >500h (ISO 4892-2) and CS<35%. Minda Industries (Noida) uses SEBS overmoulding on PP for Maruti Suzuki gear lever boots, replacing moulded PVC.

• Microphase separation: Hard/soft nanoscale domains; reversible thermoplastic/rubber duality.
• TPV: PP + dynamically crosslinked EPDM; best compression set among polyolefin TPEs.
• SEBS: Hydrogenated SBS — UV/ozone stable; automotive exterior applications.
• Compression set: Lower = better sealing; thermoset rubber < TPV < SBS.

1. ISO 37 — Tensile stress-strain of rubber; 2. ASTM D2240 — Shore A/D hardness; 3. ASTM D395 — Compression set; 4. ASTM D412 — Tensile of vulcanised rubber

1. Calculate CS for: t₀=6mm, t_s=4.5mm, t_r=5.0mm. 2. Why does SEBS resist UV degradation but SBS does not? 3. Compare TPV vs TPO for automotive weatherseal.

Q1. Microphase separation: B) Hard/soft segments thermodynamically incompatible Q2. Best compression set: C) TPV Q3. SEBS vs SBS UV stability: B) Hydrogenated backbone Q4. Shore A used for: A) Soft rubbers/elastomers Q5. Compression set measures: C) Permanent deformation after sustained compression