Polyallyl Cross-linking Coagent Reduces Byproducts in Cable Insulation
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Solution Overview
Problem
The use of peroxide cross-linking in ethylene-based polymer materials for insulation in medium to extra-high voltage cables results in the formation of unwanted byproducts, such as methane, acetophenone, and cumyl alcohol, which require removal before the jacketing layer is applied, and while coagents have been investigated to reduce peroxide usage, further improvements are needed to minimize byproduct formation.
Innovation Solution
A cross-linkable polymeric composition comprising an ethylene-based polymer, an organic peroxide, and a polyallyl cross-linking coagent with a specific allyl-to-active oxygen molar ratio, along with an antioxidant, is used to form a cross-linked coating for conductors, which reduces the amount of byproducts and enhances thermomechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If peroxide cross-linking is used to improve thermomechanical properties, then cross-linking effectiveness is improved, but byproduct formation increases
Solution Approach 1:
The patent introduces a polyallyl cross-linking coagent as an intermediary substance that mediates the cross-linking reaction. The coagent reacts with the organic peroxide to form cross-links in the ethylene-based polymer while producing fewer harmful byproducts compared to direct peroxide cross-linking. This intermediary approach allows the system to achieve the desired cross-linking effectiveness while minimizing the formation of volatile decomposition byproducts.
2Object-generated harmful factors
If cross-linking coagent is added to reduce peroxide usage, then byproduct formation is reduced, but formulation complexity increases
Solution Approach 1:
The patent optimizes the allyl-to-active oxygen molar ratio parameter within a specific range (7.5 to 16) to achieve the desired balance between byproduct reduction and cross-linking effectiveness. By carefully controlling this stoichiometric parameter, the formulation achieves efficient cross-linking with minimized byproduct formation while maintaining manageable formulation complexity. The antioxidant content is also controlled within specific ranges (0.01-5 wt% and 0.1-10 wt%) to prevent degradation without excessive complexity.
3Object-generated harmful factors
If polyallyl cross-linking coagent with specific molar ratio is used, then byproduct formation is minimized, but scorch time control becomes critical
Solution Approach 1:
The patent incorporates antioxidants (hindered phenol and/or thio compound) into the composition before cross-linking occurs. These antioxidants act in advance to prevent premature degradation and scorching of the polymer during processing and storage. By pre-equipping the system with these protective agents, the patent extends the scorch time and provides a wider processing window, thereby reducing the criticality of precise scorch time control while maintaining minimal byproduct formation.
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 solution effectively minimizes volatile decomposition byproducts, improves scorch time, and maintains mechanical and electrical properties, providing a more efficient and effective cross-linking process for cable insulation.
Implementation Method 1
an organic peroxide
Implementation Method 2
the peroxide used for cross-linking creates byproducts
Implementation Method 3
cross-linkable polymeric composition comprising an ethylene-based polymer, an organic peroxide, and a polyallyl cross-linking coagent
Implementation Method 4
the cross-linkable polymeric composition further comprises an antioxidant that is a hindered phenol or a thio compound
Data Source
Figure 1
AI summary
Cross-linkable polymeric compositions comprising an ethylene-based polymer, an organic peroxide, and a polyallyl cross-linking coagent, where the polyallyl cross-linking coagent and the organic peroxide are present in amounts sufficient to provide an allyl-to-active oxygen molar ratio of at least 1.6, based on the allyl content of the polyallyl cross-linking coagent and the active oxygen content of the organic peroxide. Such cross-linkable polymeric compositions can be employed in forming coated conductors.