Polyolefin materials, known for their excellent electrical properties, processability, and environmental performance, have become one of the most widely used insulation and sheath materials in the wire and cable industry.
Polyolefins are high-molecular-weight polymers synthesized from olefin monomers such as ethylene, propylene, and butene. They are extensively applied in cables, packaging, construction, automotive, and medical industries.
In cable manufacturing, polyolefin materials offer low dielectric constant, superior insulation, and outstanding chemical resistance, ensuring long-term stability and safety. Their halogen-free and recyclable characteristics also align with modern trends in green and sustainable manufacturing.
I. Classification by Monomer Type
1. Polyethylene (PE)
Polyethylene (PE) is a thermoplastic resin polymerized from ethylene monomers and is one of the most widely used plastics globally. Based on density and molecular structure, it is divided into LDPE, HDPE, LLDPE, and XLPE types.
(1) Low-Density Polyethylene (LDPE)
Structure: Produced by high-pressure free-radical polymerization; contains many branched chains, with a crystallinity of 55–65% and density of 0.91–0.93 g/cm³.
Properties: Soft, transparent, and impact-resistant but has moderate heat resistance (up to about 80 °C).
Applications: Commonly used as a sheath material for communication and signal cables, balancing flexibility and insulation.
(2) High-Density Polyethylene (HDPE)
Structure: Polymerized under low pressure with Ziegler–Natta catalysts; has few or no branches, high crystallinity (80–95%), and density of 0.94–0.96 g/cm³.
Properties: High strength and rigidity, excellent chemical stability, but slightly reduced low-temperature toughness.
Applications: Widely used for insulation layers, communication conduits, and fiber optic cable sheaths, providing superior weather and mechanical protection, especially for outdoor or underground installations.
(3) Linear Low-Density Polyethylene (LLDPE)
Structure: Copolymerized from ethylene and α-olefin, with short-chain branching; density between 0.915–0.925 g/cm³.
Properties: Combines flexibility and strength with excellent puncture resistance.
Applications: Suitable for sheath and insulation materials in low- and medium-voltage cables and control cables, enhancing impact and bending resistance.
(4) Cross-Linked Polyethylene (XLPE)
Structure: A three-dimensional network formed through chemical or physical crosslinking (silane, peroxide, or electron-beam).
Properties: Outstanding thermal resistance, mechanical strength, electrical insulation, and weatherability.
Applications: Extensively used in medium- and high-voltage power cables, new energy cables, and automotive wiring harnesses — a mainstream insulation material in modern cable manufacturing.
2. Polypropylene (PP)
Polypropylene (PP), polymerized from propylene, has a density of 0.89–0.92 g/cm³, a melting point of 164–176 °C, and an operating temperature range of –30 °C to 140 °C.
Properties: Lightweight, high mechanical strength, excellent chemical resistance, and superior electrical insulation.
Applications: Used primarily as a halogen-free insulation material in cables. With the growing emphasis on environmental protection, cross-linked polypropylene (XLPP) and modified copolymer PP are increasingly replacing traditional polyethylene in high-temperature and high-voltage cable systems, such as railway, wind power, and electric vehicle cables.
3. Polybutylene (PB)
Polybutylene includes Poly(1-butene) (PB-1) and Polyisobutylene (PIB).
Properties: Excellent heat resistance, chemical stability, and creep resistance.
Applications: PB-1 is used in pipes, films, and packaging, while PIB is widely applied in cable manufacturing as a water-blocking gel, sealant, and filling compound due to its gas impermeability and chemical inertness—commonly used in fiber optic cables for sealing and moisture protection.
II. Other Common Polyolefin Materials
(1) Ethylene–Vinyl Acetate Copolymer (EVA)
EVA combines ethylene and vinyl acetate, featuring flexibility and cold resistance (maintains flexibility at –50 °C).
Properties: Soft, impact-resistant, non-toxic, and aging-resistant.
Applications: In cables, EVA is often used as a flexibility modifier or carrier resin in Low Smoke Zero Halogen (LSZH) formulations, improving the processing stability and flexibility of eco-friendly insulation and sheath materials.
(2) Ultra-High-Molecular-Weight Polyethylene (UHMWPE)
With a molecular weight exceeding 1.5 million, UHMWPE is a top-tier engineering plastic.
Properties: Highest wear resistance among plastics, impact strength five times greater than ABS, excellent chemical resistance, and low moisture absorption.
Applications: Used in optical cables and special cables as high-wear sheathing or coating for tensile elements, enhancing resistance to mechanical damage and abrasion.
III. Conclusion
Polyolefin materials are halogen-free, low-smoke, and non-toxic when burned. They provide excellent electrical, mechanical, and processing stability, and their performance can be further improved through grafting, blending, and crosslinking technologies.
With their combination of safety, environmental friendliness, and reliable performance, polyolefin materials have become the core material system in the modern wire and cable industry. Looking ahead, as sectors like new energy vehicles, photovoltaics, and data communications continue to grow, innovations in polyolefin applications will further drive the high-performance and sustainable development of the cable industry.
Post time: Oct-17-2025