The Intrinsic Logic Of Performance Degradation Of Pre-twisted Composite Materials Under Thermo-oxidative Effects
Thermal-oxidation degrades pre-twisted wire composite materials through radical chain reactions, matrix scission, and interfacial decohesion. Elevated temperatures accelerate oxygen diffusion into the polymer matrix, breaking molecular bonds, decreasing mechanical elasticity, and accelerating mechanical fatigue along tensioned transmission lines.
Primary Degradation Mechanisms Under Thermal Stress
Free radicals initiate matrix breakdown when thermal energy splits unstable polymer chains inside pre-twisted wire fittings. Diffusing oxygen atoms react with active radical sites to create hydroperoxides, triggering secondary cleavage events that weaken structural stiffness.
Continued oxidative reactions increase cross-linking density, converting flexible polymeric phases into brittle networks. Microcracks form across high-stress zones under cyclic wind loading, allowing environmental moisture to enter internal strand interfaces.
Cross-Linking and Chain Scission Dynamic
| Reaction Phase | Molecular Action | Impact on Pre-twisted Wire |
| Free Radical Formation | Polymer bond cleavage via heat | Initial loss of ductility |
| Hydroperoxide Cascade | Rapid oxidation propagation | Micro-fissure formation |
| Network Restructuring | Excessive matrix cross-linking | Increased stiffness and brittleness |
| Interfacial Slippage | Matrix-reinforcement decohesion | Loss of retention force |
Interfacial Decohesion and Microstructural Failure
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Matrix embrittlement decreases load-sharing capability between individual helical strands.
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Interfacial shear stress causes micro-voids along internal reinforcement surfaces.
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Cyclic thermo-mechanical loading accelerates micro-void propagation into macroscopic delamination.
Degradation accelerates at contact boundaries where armor rod preformed units wrap around conductors. Radial pressure from helical tension concentrates mechanical shear force, driving micro-cracks through heat-stressed resin networks.
Local stress concentrations magnify thermal aging effects, leading to premature loss of clamping strength. The mechanical bond between outer preformed armour rod layers and inner conductor cores deteriorates as resin matrices lose tensile strength.
Long-Term Reliability Mitigation Strategies
Maintaining long-term structural retention requires reducing operating temperatures and choosing heat-stable resin formulations.
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Polymer Passivation: Incorporating phenolic antioxidants intercepts active peroxy radicals before chain scission propagates.
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Refined Helical Pitch: Adjusting pitch geometry distributes radial clamping pressure evenly across contact interfaces.
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Surface Barrier Coatings: Applying thermal-barrier coatings reduces oxygen ingress rates during high-current load spikes.
Monitoring thermal dissipation patterns prevents localized overheating along span support assemblies. Managing thermal-oxidative degradation preserves retention forces, ensuring extended service life across overhead utility installations.
