Conductive Liquid Silicone Rubber With SWCNT Dispersion Control
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Solution Overview
Problem
Existing conductive liquid silicone rubbers face issues with mechanical strength and stability due to high filler content, particularly with single-walled carbon nanotubes, leading to agglomeration and sedimentation, and lack uniform dispersion, which affects electrical conductivity and mechanical properties.
Innovation Solution
A two-step pre-mixing method is employed, combining single-walled carbon nanotubes with polyorganosiloxane to form a premix, then mixing with a base rubber to create a masterbatch, followed by thorough mixing with other components to ensure uniform dispersion and low filler content, using specific materials and conditions to enhance conductivity and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods (stirring, ultrasonic, high-shearing force mixing) are used to disperse conductive filler in silicone rubber, then mixing intensity can be increased, but filler aggregation and polymer chain breakage occur
Solution Approach 1:
Silane-modified polyethylene glycol serves as a mediator between the hydrophobic silicone rubber and hydrophilic conductive filler (carbon black). The compound contains both silane groups that bond with silicone rubber and polyethylene glycol chains that interact with carbon black, enabling effective dispersion without aggressive mixing that would damage the polymer structure.
Solution Approach 2:
The invention changes the chemical parameters of the base polymer by using silane-modified polyethylene glycol instead of conventional silicones. This modification allows the polymer to have dual compatibility - hydrophobic interactions with silicone rubber and hydrophilic interactions with conductive filler, achieving effective dispersion at lower mixing intensities.
2Reliability
If conductive filler is dispersed in silicone rubber, then electrical conductivity is improved, but filler aggregation reduces effectiveness
Solution Approach 1:
The silane-modified polyethylene glycol acts as a bridge between filler particles and polymer matrix, preventing filler aggregation by providing steric hindrance and chemical bonding. This intermediary ensures uniform filler distribution throughout the silicone rubber, maximizing electrical conductivity without aggregation-related defects.
Solution Approach 2:
The invention creates a composite system consisting of three components: silicone rubber base polymer, conductive filler, and silane-modified polyethylene glycol dispersant. This composite approach allows each component to contribute its specific properties - structural integrity from silicone rubber, conductivity from filler, and uniform distribution from the modified polymer dispersant.
3Ease of manufacture
If traditional dispersing agents are used, then processing is simplified, but compatibility with both hydrophobic polymer and hydrophilic filler cannot be achieved
Solution Approach 1:
The invention modifies the chemical structure of the dispersing agent by introducing both hydrophobic silane groups and hydrophilic polyethylene glycol chains. This dual-nature modification enables the dispersant to simultaneously interact with both hydrophobic silicone rubber and hydrophilic conductive filler, achieving compatibility that traditional single-nature dispersants cannot provide.
Solution Approach 2:
Different portions of the silane-modified polyethylene glycol molecule have different properties: silane groups provide affinity for silicone rubber while polyethylene glycol chains provide affinity for conductive filler. This local quality differentiation within the same molecule allows it to bridge the compatibility gap between hydrophobic polymer and hydrophilic 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 method achieves excellent electrical conductivity, mechanical strength, and weather resistance with low viscosity, avoiding agglomeration and sedimentation, suitable for electric cable accessories.
Implementation Method 1
The silane-modified polyethylene glycol dispersant, with its unique molecular structure, facilitates the uniform distribution of the conductive filler in the silicone rubber by steric hindrance and electrostatic repulsion
Implementation Method 2
The silane-modified polyethylene glycol dispersant, with its unique molecular structure, facilitates the uniform distribution of the conductive filler in the silicone rubber by steric hindrance and electrostatic repulsion
Implementation Method 3
The resulting conductive liquid silicone rubber exhibits high electrical conductivity,保持良好的柔韧性和加工性能
Data Source
AI summary
The present invention relates to a conductive liquid silicone rubber, in which the conductive filler used in the conductive liquid silicone rubber includes single-walled carbon nanotubes. The present invention uses single-walled carbon nanotubes as conductive filler for the first time to prepare a single-walled carbon nanotube conductive liquid silicone rubber composite material. At the same time, through a two-step pre-mixing method and formulation design, effectively dispersing the single-walled carbon nanotubes at a extremely small addition amount in the whole system is achieved, and the problems such as agglomeration, sedimentation and precipitation are avoided while the viscosity of the product is reduced and the processing performance is enhanced, thereby forming an effective conductive network path and preparing a conductive material with a volume resistivity of less than 100Ω·cm The resulting conductive liquid silicone rubber not only has low conductive filler addition amount, excellent electrical properties, but also has excellent physical and mechanical properties and weather resistance, as well as advantages of no pollutant generated in the vulcanization process, simple production process with no pollution, and convenient operation.