Ashby Selection Engine · CAMPUS Standards

Systematic Material Selection.Property Tradeoffs & TDS Benchmarking.

Compare 16 base polymer families and 25+ commercial TDS grades using Prof. Mike Ashby's systematic constraints-objective optimization and CAMPUS multipoint rheological curves.

Step 1: Systematic Design Constraints

Ashby Objective & Constraint Boundaries

Filter materials by application physics: Temperature · Strength · Density · Cost

Objective: Maximize Strength-to-Weight [M = σ^(2/3)/ρ]

Min. HDT (0.45 MPa)≥ 75°C

Under-the-hood > 80°C · Hot fill > 95°C

Min. Tensile Strength≥ 25 MPa

Structural rigid > 35 MPa · Films > 15 MPa

Max. Density Limit≤ 1.50 g/cm³

Polyolefins < 0.96 · Fluoropolymers > 2.1

Max. Resin Cost≤ ₹500/kg

Commodity < ₹130 · Engineering < ₹350

Step 2: Compare Base Polymer Families

Select Up to 3 Candidates (2 / 3 Selected)

Step 3: Ashby Selection Chart & Ranking

Tensile Strength (σ) vs. Density (ρ) Tradeoff Chart

Materials above the diagonal selection line deliver highest specific strength

▲ Tensile Strength (σ, MPa) [Log Scale]Selection Line: σ^(2/3)/ρ = const

Polypropylene: 35 MPa · 0.905 g/cm³

HDPE

High-Density Polyethylene: 30 MPa · 0.955 g/cm³

LDPE

Low-Density Polyethylene: 15 MPa · 0.922 g/cm³

uPVC

Polyvinyl Chloride (Rigid): 50 MPa · 1.4 g/cm³

ABS

Acrylonitrile Butadiene Styrene: 45 MPa · 1.05 g/cm³

Polycarbonate: 65 MPa · 1.2 g/cm³

PA66

Nylon 66 (Polyamide 66): 82 MPa · 1.14 g/cm³

POM

Polyoxymethylene (Acetal / Delrin): 68 MPa · 1.41 g/cm³

PET

Polyethylene Terephthalate: 60 MPa · 1.37 g/cm³

PEEK

Polyether Ether Ketone: 100 MPa · 1.3 g/cm³

PTFE

Polytetrafluoroethylene (Teflon): 25 MPa · 2.16 g/cm³

PLA

Polylactic Acid (Biopolymer): 62 MPa · 1.24 g/cm³

0.85 g/cm³ (Lightweight Polyolefins)Density (ρ, g/cm³) →2.20 g/cm³ (PTFE)

🏆 Candidate Ranking (Ashby Performance Index)

Polyether Ether Ketone (PEEK)

✕ Fails Constraint Filter

M = 16.57~₹8500/kg

Nylon 66 (Polyamide 66) (PA66)

✓ Meets All Constraints

M = 16.56~₹290/kg

Polycarbonate (PC)

✓ Meets All Constraints

M = 13.47~₹260/kg

Polylactic Acid (Biopolymer) (PLA)

✕ Fails Constraint Filter

M = 12.63~₹210/kg

Acrylonitrile Butadiene Styrene (ABS)

✓ Meets All Constraints

M = 12.05~₹185/kg

Step 4: CAMPUS Multipoint Rheology

Multipoint Dynamic Flow & Tensile Stress-Strain Curves

▲ Dynamic Melt Viscosity (η, Pa·s) [Log Scale]

PolypropyleneHigh-Density Polyethylene

10 s⁻¹ (Extrusion / Parison)Shear Rate (γ̇, s⁻¹) →10,000 s⁻¹ (Injection Mold Gate)

Step 5: Full Engineering Property Matrix

Brandrup & CAMPUS Verified Technical Data

Property Parameter	Polypropylene (PP)	High-Density Polyethylene (HDPE)
Specific Density (ASTM D792)	0.90–0.91 g/cm³ (Nominal: 0.905)	0.94–0.97 g/cm³ (Nominal: 0.955)
Glass Transition Temp (Tg)	−10°C to 0°C	−120°C (Flexible sub-zero)
Crystalline Melting Point (Tm)	160–170°C	128–135°C
Tensile Strength at Yield (ASTM D638)	30–40 MPa (Typical: 35 MPa ±5%)	25–35 MPa (Typical: 30 MPa ±5%)
Flexural Modulus (ASTM D790)	1,200–1,700 MPa (1.45 GPa)	900–1,300 MPa (1.10 GPa)
Heat Deflection Temp (HDT 0.45 MPa)	100–108°C (0.45 MPa)	75–85°C (0.45 MPa)
Notched Izod Impact (ASTM D256)	20–80 J/m (Izod notched)	40–120 J/m
Processing Window	200–260°C	180–240°C
Mold Shrinkage Rate	1.2–2.2%	1.5–3.0%
Chemical Resistance Summary	Excellent to acids/alkalis; susceptible to aromatic solvents	Outstanding resistance to aqueous acids, bases, salts
Indian Industrial Producers	Reliance (Repol), IOCL (Propel), GAIL, Haldia Petrochem	Reliance (Relene), IOCL (Propel), GAIL, OPaL

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