Optical Fiber Cable Filling Composition with Thixotropic Block Copolymer
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Solution Overview
Problem
There is a need for improved filling compositions to protect the structural and functional integrity of optical fiber cables from stresses and water ingress, which can lead to signal loss or attenuation, and to maintain consistent viscosity and oil retention across varying temperatures.
Innovation Solution
A filling composition comprising a selectively hydrogenated isoprene-styrene block copolymer with at least 40 wt. % polystyrene content, combined with an oil and optional additives, characterized by a thixotropic ratio of 2-10, a drop point of at least 200° C., and a cone penetration of less than 350 dmm, providing excellent oil retention and viscosity consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional filling compositions are used in optical fiber cables, then the cables can be manufactured and installed, but the filling composition fails to maintain consistent viscosity and oil retention across varying temperatures, compromising structural and functional integrity
Solution Approach 1:
The patent applies parameter changes by carefully controlling the molecular weight of the polyisoprene block (80-100 kg/mole) and polystyrene block (60-110 kg/mole), and the polystyrene content (40-50 wt.%), to achieve a filling composition that maintains stable viscosity and oil retention across varying temperatures. The selective hydrogenation degree is also controlled to optimize these properties.
Solution Approach 2:
The patent uses a composite material approach by combining a selectively hydrogenated isoprene-styrene block copolymer with specific oil components. This composite system provides both the necessary viscosity consistency and oil retention properties that single materials cannot achieve alone, thereby improving reliability under temperature variations.
2Reliability
If the filling composition has high viscosity to protect cable structure, then structural integrity is improved, but the composition becomes difficult to process and apply during cable manufacturing
Solution Approach 1:
The patent applies dynamics by utilizing the thixotropic properties of the filling composition, which allows the viscosity to change under different shear conditions. During cable manufacturing when shear stress is applied, the viscosity decreases for easy processing and application. Once the shear stress is removed, the viscosity increases to provide structural integrity and protection.
3Stability of the object's composition
If the filling composition uses high polystyrene content to improve viscosity stability, then viscosity consistency is improved, but the oil retention capability deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the polystyrene content within a specific range (40-50 wt.%) rather than using maximum possible content. This balanced parameter selection ensures both viscosity consistency and adequate oil retention. The molecular weight parameters of both polyisoprene and polystyrene blocks are also controlled to achieve the desired balance between these properties.
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 effectively protects optical fiber cables by maintaining consistent viscosity and oil retention at high temperatures, preventing oil bleed and ensuring structural integrity while allowing for easy fiber movement during manufacturing, thus enhancing the cables' operational reliability.
Implementation Method 1
The filling composition is characterized as having a thixotropic ratio of 2-10
Implementation Method 2
a drop point of at least 200° C.
Data Source
AI summary
A filling composition is disclosed, the composition comprises (i) between 4 to 20 wt. % of a selectively hydrogenated isoprene-styrene block copolymer having a structure S-EP with at least 40 wt. % polystyrene content, a total diblock apparent molecular weight of at least 160 kg/mole, the polystyrene block S has a true molecular weight in the range of 60 to 110 kg/mole, and the polyisoprene block (EP) has a molecular weight in the range of 80-100 kg/mole, (ii) an oil, and (iii) optional additives. The filling composition is characterized as having a thixotropic ratio of 2-10, a drop point of at least 200° C., and a cone penetration at 25° C. of <500 dmm.