Phase-Change Material Gel Containment via SEBS Copolymer
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Solution Overview
Problem
Phase-change materials like n-tetradecane, due to their low surface tension, tend to leak through defects or permeate through permeable containers, compromising the temperature control of temperature-sensitive materials.
Innovation Solution
A gel is developed by combining phase-change materials with a gelling agent, such as SEBS or SEPS triblock copolymers, which forms a viscoelastic liquid that solidifies upon cooling, providing enhanced containment and thermal exchange properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phase-change materials with low surface tension (e.g., n-tetradecane) are used, then thermal exchange performance is improved, but leakage through defects and permeation through container walls occur
Solution Approach 1:
The patent combines phase-change materials with gelling agents to create a composite gel formulation. The gelling agent forms a three-dimensional network structure that entraps the phase-change material, preventing leakage while maintaining thermal exchange capabilities. This composite approach allows the system to retain the high thermal conductivity of pure phase-change materials while eliminating their tendency to leak through defects or permeate containers.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the phase-change material by incorporating it into a gel matrix. The gel structure changes the effective viscosity and surface tension characteristics of the phase-change material, transforming it from a free-flowing liquid prone to leakage into a contained gel that maintains thermal performance while preventing unwanted flow and permeation.
2Reliability
If gelling agents are added to phase-change materials to prevent leakage, then containment reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes the gelation temperature parameter of the gelling agent to simplify manufacturing. By controlling the temperature during mixing and processing, the formulation transitions between liquid and gel states, enabling easy filling and processing at elevated temperatures and spontaneous gelation at lower temperatures. This temperature-dependent parameter change eliminates the need for complex mixing equipment or additional processing steps.
3Reliability
If gelling agents are added to phase-change materials, then leakage prevention is improved, but gel preparation complexity increases
Solution Approach 1:
The patent exploits the temperature-dependent gelation behavior of the gelling agent to simplify preparation. The formulation is mixed at temperatures above the gelation point where components remain liquid and easily mixable, then cooled to trigger spontaneous gelation. This parameter-based approach eliminates the need for complex gelation control mechanisms while ensuring consistent leakage prevention.
Solution Approach 2:
The gelation process occurs spontaneously when the formulation is cooled to ambient temperature, without requiring external intervention or additional processing steps. The gelling agent self-organizes into a three-dimensional network structure that traps the phase-change material, providing automatic leakage prevention once the temperature drops below the gelation point.
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 gel effectively maintains temperature-sensitive materials within a desired range, preventing leakage and maintaining thermal performance across multiple freeze/thaw cycles, while being suitable for use in various packaging formats.
Implementation Method 1
combining phase-change materials with a gelling agent, such as SEBS or SEPS triblock copolymers, which forms a viscoelastic liquid that solidifies upon cooling
Implementation Method 2
maintaining thermal performance across multiple freeze/thaw cycles
Implementation Method 3
phase-change material is selected such that it has a phase change temperature that is within the desired temperature range
Data Source
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AI summary
Gel including a phase-change material and a gelling agent. In one embodiment, the phase-change material may be n-tetradecane and/or n-hexadecane. The gelling agent, which may constitute up to about 10%, by weight, of the gel, may be a high molecular weight styrene-ethylene-butylene-styrene (SEBS) triblock copolymer with a styrene:rubber ratio of about 30:70 to 33 :67 % by weight. To form the gel, the phase-change material and the gelling agent may be mixed at a temperature at which the phase-change material is in a liquid state and which is below the flash point of the phase-change material and at which the mixture is not a viscoelastic liquid, whereby a non-homogeneous mixture is produced. The non- homogeneous mixture may then be heated to a temperature that is below the flash point of the phase-change material and at which a viscoelastic liquid is formed. The viscoelastic liquid may then be cooled to room temperature.