Cable Insulation Polymer Composition for Above-70°C Strength Retention
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Solution Overview
Problem
Existing low-voltage power transmission cables lack optimized thermomechanical and electrical properties, particularly at temperatures above 70°C, due to suboptimal polymer compositions used in their insulation layers.
Innovation Solution
A cable design featuring a polymer composition with at least 50 wt% homophase propylene polymer, a homophase ethylene polymer with an elastic modulus greater than 300 MPa, and up to 10 wt% heterophase propylene polymer, ensuring improved thermomechanical and electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional polymer compositions are used in cable insulation layers, then manufacturing cost is reduced, but thermomechanical properties deteriorate at temperatures above 70°C
Solution Approach 1:
The patent applies composite materials by combining homophase propylene polymer (at least 50 wt%) with homophase ethylene polymer having high elastic modulus (>300 MPa). This specific composite composition enables the cable to maintain both flexibility and thermomechanical strength at temperatures above 70°C, resolving the contradiction between operating temperature and strength retention.
Solution Approach 2:
The patent changes the material parameters by specifying precise compositional parameters: homophase propylene polymer content (≥50 wt%), homophase ethylene polymer with elastic modulus >300 MPa, and heterophase propylene polymer content (≤10 wt%). These parameter specifications ensure optimal thermomechanical performance at elevated temperatures while maintaining electrical properties.
2Ease of operation
If homophase propylene polymer is used as the main component, then flexibility is improved, but electrical performance may deteriorate
Solution Approach 1:
The patent changes the compositional parameters to achieve optimal balance: homophase propylene polymer is limited to at least 50 wt% (not higher) to maintain flexibility while homophase ethylene polymer with elastic modulus >300 MPa is included to preserve electrical performance. This parameter control resolves the contradiction between flexibility and electrical reliability.
Solution Approach 2:
The composite of homophase propylene polymer and homophase ethylene polymer creates synergistic effects where the propylene provides flexibility and the ethylene component maintains electrical insulation properties, resolving the contradiction between ease of operation and reliability.
3Ease of manufacture
If heterophase propylene polymer is used to reduce cost, then manufacturing cost is reduced, but thermomechanical properties deteriorate
Solution Approach 1:
The patent controls the parameter of heterophase propylene polymer content to be at most 10 wt%, limiting its negative impact on thermomechanical properties while still allowing cost benefits. This parameter constraint resolves the contradiction between manufacturing cost and thermomechanical strength.
Solution Approach 2:
The patent applies local quality by allowing heterophase propylene polymer (lower quality component) to be present only in limited amounts (≤10 wt%), while the majority composition (≥90 wt%) consists of higher quality homophase polymers that provide superior thermomechanical properties. This graded quality approach balances cost and performance.
Data Source
AI summary
The invention relates to a cable comprising at least one electrically insulating layer obtained from a polymer composition comprising at least one homophasic propylene polymer, and at least one homophasic ethylene polymer having an elastic modulus greater than 300 MPa, said propylene and ethylene polymers being in specific proportions.