How do the mechanical properties of halogen-free low-smoke sheathing compounds change in different temperature ranges?

The mechanical properties of halogen-free low-smoke sheathing compounds change significantly with temperature. The following is a detailed analysis of the changes in its mechanical properties in different temperature ranges:

ML-FH9001 90℃ Radiation Cross-Linked Halogen-Free Low Smoke Flame Retardant Sheath Compound

1. Normal temperature range (20℃ - 30℃)
At normal temperature, halogen-free low-smoke sheathing compounds generally exhibit good mechanical properties, which is the basic condition for their design and application.
Tensile strength: Reach a high level, usually between 10 - 20 MPa, the specific value depends on the material formulation and production process.
Elongation at break: Generally high, usually between 150% - 300%, indicating that the material has good flexibility and tear resistance.
Hardness: Moderate, generally between Shore hardness 60 - 75A, which can ensure the mechanical protection of the cable without being too hard and brittle.
Abrasion resistance and chemical resistance: Shows good abrasion resistance and chemical corrosion resistance, suitable for general industrial and civil environments.

2. Low temperature range (-20℃ - 0℃)
Under low temperature environment, the mechanical properties of halogen-free low smoke sheathing compounds will change significantly, mainly manifested as follows:
Tensile strength: may decrease slightly, but usually still maintain a high level.
Elongation at break: significantly reduced, the flexibility of the material becomes worse and it is easy to become brittle. This is because low temperature restricts the movement of polymer segments, resulting in a decrease in the ductility of the material.
Hardness: may increase, and the material becomes harder and more brittle.
Impact resistance: significantly reduced, the material is more likely to break due to external force impact at low temperature.
Chemical resistance: Although low temperature itself has little effect on chemical resistance, the increased brittleness of the material may make chemical media more easily penetrated.

3. High temperature range (40℃ - 80℃)
Under high temperature environment, the mechanical properties of halogen-free low smoke sheathing compounds will also change, mainly manifested as follows:
Tensile strength: may decrease, especially when close to the heat deformation temperature of the material. This is because high temperature intensifies the movement of polymer segments, resulting in a decrease in the mechanical strength of the material.
Elongation at break: may increase, the material becomes more flexible, but the strength decreases.
Hardness: may decrease, the material becomes softer.
Thermal stability: requires special attention. Halogen-free low-smoke sheath compounds usually contain flame retardants and fillers. High temperatures may accelerate the decomposition or migration of these additives, affecting the long-term stability of the material.
Chemical resistance: At high temperatures, the chemical resistance of the material may be affected to a certain extent, especially the tolerance to some organic solvents and acid-base environments.

4. Extreme temperature range (below -20℃ or above 80℃)
At extreme temperatures, the performance changes of halogen-free low-smoke sheath compounds are more significant:
Low temperature extremes (below -20℃): The brittleness of the material increases further, and the elongation at break decreases significantly, and may even be close to zero. The tensile strength will also decrease significantly, and the mechanical properties of the material will be almost completely lost.
High temperature extremes (above 80℃): The material may experience thermal aging phenomena, such as surface cracking, color changes, and a significant decrease in strength. The decomposition of flame retardants may cause the flame retardant properties of the material to decrease, and the low smoke characteristics may also be affected.

5. Influencing factors
The mechanical properties of halogen-free low-smoke sheath compounds are affected by many factors, including:
Formula design: The selection of different polymer matrices (such as PVC, polyolefins, rubber, etc.) and additives (such as flame retardants, plasticizers, stabilizers) has a significant impact on the mechanical properties.
Production process: Extrusion speed, temperature control, cooling method, etc. will affect the microstructure and final performance of the material.
Environmental factors: The presence of humidity and chemical media will also have an indirect impact on the mechanical properties of the material.

6. Improvement suggestions
In order to optimize the mechanical properties of halogen-free low-smoke sheath compounds in different temperature ranges, the following measures can be taken:
Formula optimization: Improve the temperature adaptability of the material by adding low-temperature or high-temperature resistant polymer blends.
Nano material enhancement: The introduction of nano fillers (such as nano silica, nano calcium carbonate) can improve the mechanical strength and toughness of the material.
Process adjustment: Optimize the extrusion process parameters to ensure the uniformity of the material and the stability of the microstructure.
Surface treatment: Special treatment of the sheath surface, such as coating with a temperature-resistant coating, to improve its performance at extreme temperatures.