🧩 PP+Rand – Technical Random Copolymer Polypropylene
(Weldable semi-transparent and flexible plastic, used in technical parts requiring thermal resistance and aesthetic appeal)
🔹 What is PP+Rand
PP+Rand (or PP-R) is a random copolymer polypropylene, obtained by polymerizing PP with a small proportion of ethylene (2–5%) to increase its elasticity and impact resistance.
It features superior thermal stability and partial transparency. Unlike PP-H (homopolymer), PP-R is softer, less brittle, and welds more easily without significant deformation. It is widely used in automotive technical systems and industrial applications.
🔧 Composition
- PP (Polypropylene) – main component
- Ethylene (2–5%) – added for flexibility and clarity
- Additives – antioxidants, UV stabilizers, flow agents
- May include mineral fibers or technical colorants
🚗 Where PP+Rand is used in the automotive industry
| Component | Example parts | Observations |
| Interior | Covers, panels, sensor housings | Smooth finish, easy to clean |
| Body / Exterior | Small caps, rigid gaskets | Cold and vibration resistant |
| Engine Compartment | Sensor housings, flexible tubes | Stable at temperatures up to 120 °C |
| Other Applications | Technical parts, prototypes | Easy to process and weld |
🔧 Welding temperatures and methods
| Method | Optimal temperature | Observations |
| Hot air | 260 – 280 °C | Most used method for clean joints |
| Heat plate (mirror) | 250 – 270 °C | Recommended for fittings or covers |
| Manual extrusion | 240 – 260 °C | For long cracks or thin edges |
| Ultrasonic | — | Industrial possibility for thin parts |
🔩 What to weld PP+Rand with (Material compatibility)
The question “what to weld PP+Rand with” is common, especially in technical part repairs. As a PP copolymer, it welds perfectly with other types of polypropylene, particularly PP-C and PP-H.
✅ Compatible:
- PP+Rand ↔ PP+Rand (PP-R) – ideal combination
- PP+Rand ↔ PP-C / PP-H – excellent compatibility
- PP+Rand ↔ PP+HI / PP+EPDM / PP+TPO – partially compatible
- PP+Rand ↔ PP-TD / PP-MD – compatible, but different rigidity
❌ Incompatible:
- PE, ABS, ASA, PC, PA, PVC – will not bond, different melting points
💡 ReplastMD Recommendation:
Use original PP-R (random copolymer) rods at a temperature of 265–275 °C. Clean the area with isopropyl alcohol and apply constant pressure during melting for a uniform joint.
🏭 Manufacturers and trade names
| Manufacturer | Brand / Series | Country / Region |
| Borealis | Daplen® R Series | Austria |
| LyondellBasell | Hostacom® R / Moplen® RP | Germany / Netherlands |
| SABIC | PP-R Compound | Netherlands / Global |
| TotalEnergies | Lumicene® PP-R | France |
| Hyundai EP | Polytron® R | South Korea |
| Ravago | Enyglos® PP-R | EU |
🧠 How to identify PP+Rand
- Engraved marking: >PP-R< or >PP-Rand<
- Smooth, semi-glossy surface, sometimes translucent
- Yellow-blue flame, faint paraffin smell
- Softens uniformly at 270 °C, no bubbles
- Floats completely in water (density < 1 g/cm³)
🛠️ PP+Rand Welding at ReplastMD:
At our service center in Chisinau (Ciocana sector), ReplastMD performs professional PP-Rand welding for:
- covers, panels, and technical flexible parts
- restoration of broken zones, mounts, and deformed corners
- clean repairs without cracks or bubbles