Cross-Linked Polyethylene (PEX)
Introduction
Cross-linked polyethylene (PEX) is a form of polyethylene in which the polymer chains are chemically or physically linked, enhancing its mechanical strength, thermal stability, and chemical resistance. The cross-linking process transforms standard thermoplastic polyethylene into a thermoset material, making it suitable for high-performance applications in plumbing, heating systems, insulation, medical devices, and wire coatings.
PEX has gained widespread adoption due to its durability, flexibility, and resistance to corrosion, scale, and chlorine, offering a reliable alternative to traditional materials such as copper and PVC.
Types of Cross-Linking Methods
1. PEX-A (Peroxide Method)
Formed by introducing peroxide during extrusion, creating the highest degree of cross-linking (~70–85%).
Advantages: Superior flexibility, thermal memory, and crack resistance.
Applications: Plumbing, underfloor heating systems.
2. PEX-B (Silane Method)
Created by grafting silane molecules onto polyethylene chains followed by water curing.
Cross-linking degree: ~65–70%.
Advantages: High chemical resistance and lower manufacturing cost.
Applications: Potable water and heating systems.
3. PEX-C (Radiation Method)
Produced by electron beam or gamma radiation exposure, causing physical cross-linking.
Cross-linking degree: ~60–70%.
Advantages: Eco-friendly process and consistent quality.
Applications: Electrical insulation, industrial tubing.