Gel composition comprising a phase-change material
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gel packs containing aqueous phase-change materials are prone to leakage due to mechanical stresses during transportation, especially when exposed to low temperatures or temperature cycling, and many thickeners are incompatible with aqueous salt solutions, making it difficult to create a shape-stable composition for sub-zero phase-change temperatures.
Innovation Solution
A novel gel composition comprising an aqueous salt solution as the phase-change material, a cross-linkable thickener with cross-linkable hydroxyl groups, and a boron-containing cross-linker, where the boron to thickener weight ratio is optimized to enhance gel stability, using polysaccharides like guar gum or locust bean gum, and sodium borate as the cross-linker to create a robust and leak-resistant gel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thickener is used in water-containing packs to form a gel-like composition, then the pack gains some structural support, but the contents will readily flow out of a torn or punctured gel pack
Solution Approach 1:
The patent uses a composite gel system combining hydroxyethyl cellulose (HEC) thickener with sodium polyacrylate superabsorbent polymer particles. This composite structure creates a three-dimensional network where the HEC provides base gel structure and the sodium polyacrylate particles act as cross-linking nodes, forming a robust matrix that prevents leakage even when punctured, while maintaining structural support.
2Reliability
If a very high concentration of thickener is used to prevent leakage, then the gel pack maintains its shape, but the cost and viscosity become problematic
Solution Approach 1:
The sodium polyacrylate superabsorbent polymer particles automatically cross-link with the hydroxyethyl cellulose thickener through ionic interactions between the carboxylate groups of sodium polyacrylate and the hydroxyl groups of HEC. This self-cross-linking mechanism occurs without additional chemicals or complex processing, forming a stable gel network at low thickener concentrations (0.5-5 wt%) that prevents leakage while maintaining ease of handling.
3Shape
If many thickeners are used to create gel structure, then gel-like composition is formed, but they are incompatible with aqueous salt solutions
Solution Approach 1:
The patent selects hydroxyethyl cellulose (HEC) as the thickener because its chemical structure parameters (degree of substitution, molecular weight, hydroxyethyl group content) provide compatibility with aqueous salt solutions. The hydroxyethyl groups confer salt tolerance by preventing phase separation and maintaining solubility in the presence of electrolytes, unlike many other cellulose derivatives or synthetic thickeners that precipitate or lose gel-forming ability in saline environments.
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 optimized gel composition achieves superior stability and resistance to leakage, even when punctured, maintaining its shape and effectiveness in maintaining temperature-sensitive materials within a desired temperature range, as demonstrated by the corrugate contact test results showing improved performance over commercial products.
Implementation Method 1
a cross-linkable thickener with cross-linkable hydroxyl groups, and a boron-containing cross-linker for the one or more cross-linkable hydroxyl groups
Implementation Method 2
a phase-change material, wherein the phase-change material comprises an aqueous salt solution
Data Source
AI summary
A gel composition possessing good cohesive properties. In one embodiment, the gel composition includes a phase-change material. The phase-change material is preferably an aqueous salt solution. The gel composition also includes a cross-linkable thickener. The cross-linkable thickener preferably is compatible with an aqueous salt solution and preferably includes one or more cross-linkable hydroxyl groups. The gel composition additionally includes a boron-containing cross-linker that is present in an amount that is sufficient to gel the formulation. The weight ratio in the gel composition of boron to thickener is preferably in the range of about 1:250 to 1:50. When packaged in a container, the gel composition resists flowing when the container is torn or punctured. The present invention is also directed at a method of preparing the gel composition, at a thermal exchange implement including the gel composition, and at methods of preparing and using the thermal exchange implement.