🧩 PP+HI – High Impact Polypropylene
(Weldable plastic with increased shock resistance, used in automotive parts exposed to impacts and vibrations)
🔹 What is PP+HI
PP+HI (High Impact Polypropylene) is a polypropylene modified for impact resistance by adding elastomers (EPR or EPDM).
This combination provides an elastic material, resistant to cracking and cold, ideal for car bumpers, liners, and exterior components that must absorb shocks without breaking.
🔧 Composition
- PP (Polypropylene) – base matrix
- HI (High Impact Modifiers) – synthetic rubber (EPR, EPDM) 10–20%
- Additives – UV stabilizers, antioxidants, technical colorants
- Variants: PP-HI10, PP-HI15, PP-HI20
🚗 Where PP+HI is used in the automotive industry
| Component | Example parts | Observations |
| Body / Exterior | Bumpers, spoilers, mudguards | Flexible, does not crack on impact |
| Interior | Door panels, covers, trims | Matte surface, elastic |
| Engine Compartment | Secondary parts, covers, supports | Vibration resistant |
| Aftermarket / Tuning | Sport spoilers, extensions | Lightweight, malleable, easy to weld |
🔧 Welding temperatures and methods
| Method | Optimal temperature | Observations |
| Hot air | 260 – 280 °C | Uniform melting, no bubbles |
| Heat plate (mirror) | 250 – 270 °C | Clean and flexible weld |
| Manual extrusion | 240 – 260 °C | For long cracks and corners |
| Ultrasonic | — | Only for small and thin parts |
🔩 What to weld PP+HI with (Material compatibility)
Many ask what to weld PP+HI with — the material remains 100% compatible with all PP forms, but requires a welding rod with the same level of elastic modification to maintain flexibility.
✅ Compatible:
- PP+HI ↔ PP+HI – ideal combination, elastic joint
- PP+HI ↔ PP-C / PP-H / PP-TD10 – good compatibility
- PP+HI ↔ PP-R / PP-MD – compatible, but rigidity differs slightly
- PP+HI ↔ PE-LD – partial bonding possible (both are soft)
❌ Incompatible:
- ABS, ASA, PC, PA, PVC – different temperatures and chemistry
💡 ReplastMD Recommendation:
Use original PP-HI or PP-C welding rods at 270 °C.
Avoid overheating — the rubber in the composition can produce bubbles at temperatures above 290 °C.
🏭 Manufacturers and trade names
| Manufacturer | Brand / Series | Country / Region |
| LyondellBasell | Hostacom® HI | Germany / Netherlands |
| Borealis | Daplen® HI | Austria |
| SABIC | PP High Impact Series | Netherlands / Global |
| TotalEnergies | Lumicene® HI | France |
| Hyundai EP | Polytron® HI | South Korea |
| Ravago | Enyglos® HI | EU |
🧠 How to identify PP+HI
- Engraved marking: >PP-HI< or >PP-EPDM<
- Yellow-blue flame, smells like paraffin
- Floats in water
- Melts at 270 °C, soft and uniform melting
- Matte surface, elastic, not brittle
💡 ReplastMD Practical Test: If the part is slightly flexible, softens uniformly at 270 °C, and returns to shape after cooling without cracks → PP-HI confirmed.