🧩 PHB – Polyhydroxybutyrate

PHB is a biodegradable and biocompatible material synthesized by bacteria from sugars or vegetable oils. PHB is a natural semi-crystalline polyester, rigid, translucent, and glossy, used in bio-parts, covers, films, and eco-friendly components. It belongs to the PHA (Polyhydroxyalkanoates) family, alongside PHBV, PHBH, and Nodax®, being one of the purest bioplastics in existence.

🔹 What is PHB PHB (Polyhydroxybutyrate) is an aliphatic biopolymer with a chemical structure similar to polypropylene, but biologically produced. It features high rigidity and gloss but is brittle at low temperatures. It degrades completely in soil and water without toxic residues, making it a premium option for precision bio-parts.

🔧 Composition and Properties

• Structure: Natural bio-polyester (poly-3-hydroxybutyrate).
• Source: Bacterial fermentation (sugar, molasses, vegetable oils).
• Density: 1.23 – 1.26 g/cm³.
• Melting Point: 170 – 180 °C.
• Continuous Working Temperature: –10 °C to +90 °C.
• Chemical Resistance: Good (oils, fats, cold detergents).
• UV Resistance: Medium.

🚗 Automotive Applications

• Bio Interior Elements: Covers, inserts, panels (rigid, glossy, biodegradable).
• Rigid Bio-Gaskets: Protectors, handles, plugs (durable, smooth, resistant).
• Bio Films and Layers: Thin sheets, protective coatings (compostable, clear, odorless).
• Bio Prototype Parts: Eco-friendly samples and tests (bio-replacement for PP).

🔧 Welding Temperature and Methods

• Hot Air: ✅ 110 – 130 °C (slow welding, controlled flow).
• Heat Plate: ✅ 120 – 130 °C (smooth, glossy joint).
• Manual Extrusion: ⚠️ 130 – 140 °C (possible, but requires constant pressure).
• Chemical Bonding: ✅ Recommended (natural polyester-based bio-adhesives).

🔩 Welding Compatibility

• ✅ Excellent Compatibility: PHA, PHBV, PBS, PBAT, PLA, Ecoflex®.
• ✅ Good Compatibility: Bioplast, BioFlex, Mater-Bi, EnPol®.
• ❌ Incompatible: PP, PE, ABS, PA, PC, PVC, POM.

💡 ReplastMD Recommendation: PHB welds efficiently with hot air at 120 °C, but requires slow cooling to avoid cracking caused by its crystalline rigidity. For more flexible joints, PHB or PHBV welding rods are recommended.