Halogen-Free Mineral Filler Polymer Composition for LSZH Cables
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Solution Overview
Problem
Electrical cables with protective jackets made from LSZH materials face issues with high water uptake and brittleness due to the use of mineral flame retardants, which compromise their ductility and flame retardance.
Innovation Solution
A polymer composition comprising an olefinic polymer, a halogen-free mineral filler, and a compatibilizing agent, with the filler constituting 20-80 wt.% of the composition, which exhibits low water uptake and maintains ductility while providing flame retardant properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mineral flame retardants are employed in very high levels to achieve flame retardance and smoke suppression, then flame retardant properties are improved, but water uptake increases and the composition becomes brittle
Solution Approach 1:
A compatibilizing agent is introduced as an intermediary substance between the olefinic polymer and the halogen-free mineral filler. This compatibilizer improves the interfacial adhesion and compatibility between the polymer matrix and the mineral filler particles, allowing the system to maintain both flame retardant properties and reduced water uptake. The compatibilizing agent prevents excessive water absorption by improving the overall morphology and reducing voids at the interface.
2Reliability
If mineral flame retardants are employed in very high levels to achieve flame retardance, then flame retardant properties are improved, but the composition becomes brittle and loses ductility
Solution Approach 1:
The compatibilizing agent acts as a mediator that improves the stress transfer between the polymer matrix and the mineral filler. By enhancing the interfacial adhesion, the compatibilizer prevents stress concentration at the filler-polymer interface, thereby maintaining the ductility and toughness of the composite even at high filler loadings required for effective flame retardance.
3Object-generated harmful factors
If halogen-free mineral filler is used to achieve zero halogen and smoke suppression, then environmental safety is improved, but water uptake increases
Solution Approach 1:
The compatibilizing agent reduces water uptake by improving the compatibility between the hydrophobic olefinic polymer and the hydrophilic mineral filler. This better compatibility reduces the formation of water pathways and voids at the interface, thereby maintaining low water uptake while preserving the smoke suppression benefits of the halogen-free mineral filler.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves a water uptake of 5 wt.% or less and tensile elongation at break of 100% or more, while effectively retarding fire and reducing smoke production, as evidenced by its LOI, peak heat release rate, and smoke density.
Implementation Method 1
When exposed to high temperatures, water molecules from this filler can be released in an endothermic reaction, which quench the surface of the surrounding materials and can thus provide a degree of flame retardance and smoke suppression.
Data Source
AI summary
A polymer composition that comprises an olefinic polymer, a flame retardant that includes a halogen-free mineral filler, and a compatibilizing agent is provided. The halogen-free mineral filler constitutes from about 20 wt. % to about 80 wt. % of the composition. The composition may exhibit a degree of water uptake of about 5 wt. % or less after being immersed in water for seven days at a temperature of 23° C.