Specific classification and application of cable PE insulaiton material.
The insulation materials of cables are diverse, among which PE, as a major category, can be seen in various types of cable sheath materials. This article will focus on the traditional material of PE and introduce its specific classification, including advantages and disadvantages.
1, Classification of PE insulation materials
PE can be specifically divided into:
1. HDPE (high-density PE)
2. MDPE (medium density PE) is not widely used
3. LDPE (Low Density PE)
4. LLDPE (Linear Low Density PE)
5. FRPE (flame retardant PE)
6. Cellular or FOAM PE (foam PE)
7. XL-PE (cross-linked PE)
2, Advantages and disadvantages of PE insulation
1. Advantages: PE material is soft, water-resistant, cold resistant, wear-resistant, and has excellent electrical characteristics.
2. Disadvantages: PE is prone to non extinguishing, heat-resistant, and rapidly ages at high temperatures.
3. Usage: Generally used for communication twisted pair cables, high-frequency coaxial cables, high-voltage cables, submarine cables, outdoor self-propelled cables, wires, communication cables, etc.
4. How to identify PE material: Burning blue flame light, the combustion zone is melted and transparent, with the smell of sol droplets and candles, it belongs to the category of flame retardant plastic and can continue to burn.
3, Analysis of different types of PE materials
1. HDPE high-density polyethylene
High density polyethylene is produced by low-pressure method, so it is also known as low-pressure polyethylene.
(1) Advantages: Chemical resistance, good electrical properties
(2) Disadvantages: Poor heat resistance, relatively low physical properties, soft surface
HDPE has a high coefficient of thermal expansion and is prone to failure under mechanical and thermal compression The specific gravity ranges from 0.94 to 0.97. Elongation rate of 100-400%, tensile strength of 1.0-2.0kg/mm2 (1kg/mm2=1422PSI). UL444 safety regulations require an elongation rate of 300% min and a tensile strength of 2400 PSI min.
2. LDPE Low Density Polyethylene
Traditional low-density polyethylene is produced by free radical polymerization of polymerized ethylene with oxygen or peroxide as initiators at high temperature and high pressure, hence it is also known as high-pressure polyethylene.
(1) Advantages: low density, chemical resistance, impact resistance.
(2) Disadvantages: Very low strength/rigidity, poor heat resistance, high coefficient of thermal expansion, and easy failure under mechanical and thermal compression.
The specific gravity of LDPE is about 0.91~0.93. Elongation rate of 350~700%, tensile strength of 1.0~2.0kg/mm2 (1kg/mm2=1422PSI). UL444 safety regulations require an elongation of 350% min and a tensile strength of 1400 PSI min.
3. LLDPE linear low-density polyethylene
Compared with ordinary low-density polyethylene, it consumes less energy and has a higher yield, especially its physical and chemical properties are much better than ordinary low-density polyethylene, and its applications are also quite extensive. It is relatively inexpensive and has good mechanical properties, such as tear resistance, puncture resistance, tensile strength, and resistance to environmental stress cracking.
The specific gravity of LLDPE is about 0.915~0.945, and its elongation and tensile strength are higher than LDPE.
4. XL-PE (Cross linked PE) cross-linked PE
Cross linked insulation has become dominant in power cables, replacing oil paper insulation and gradually replacing PVC plastic insulation. Although there are many varieties of cross-linked insulation, they are mainly divided into two categories: physical and chemical cross-linking, and their insulation quality is completely consistent.
(1) Advantages: It has good insulation quality, high cross-linking degree, and good weather resistance. It is an ideal process method for various flexible wires, equipment wires, and high temperature (105 ℃ and above) and flame-retardant wires and cables.
(2) Disadvantages: Uneven illumination, repeated illumination during production, too many cable bends, and easy injection of space charges into insulation.
