Polyamide Porous Membrane Gamma Crystal Control
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Solution Overview
Problem
Conventional polyamide porous membranes have insufficient water permeability and require improvement while maintaining membrane separation performance.
Innovation Solution
A polyamide porous membrane with a γ crystal ratio of 38% or more to the total amount of α and γ crystals, produced using a solution containing a polyamide resin, sulfolane, and dimethyl sulfone, employing the thermally-induced phase separation method and non-solvent-induced phase separation method, with a mass ratio of sulfolane to dimethyl sulfone between 0.8 and 2.5, to enhance liquid permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional polyamide porous membranes are used, then membrane separation performance is maintained, but water permeability is insufficient
Solution Approach 1:
The invention changes the crystal structure parameters of the polyamide membrane by controlling the formation of γ-crystals through specific processing conditions (temperature, solvent composition, coagulation bath conditions). By adjusting these parameters, the membrane achieves both high water permeability and maintained separation performance, resolving the contradiction between quantity of substance and reliability.
Solution Approach 2:
The invention creates a composite crystal structure within the polyamide membrane, combining α-crystals and γ-crystals in a specific ratio. The γ-crystals provide hydrophilic pathways for water permeation while the α-crystals maintain structural integrity and separation performance, thus resolving the contradiction through material composition.
2Strength
If polyolefins or polysulfones are used, then membrane strength is improved, but water permeability decreases due to hydrophobicity
Solution Approach 1:
The invention changes the surface properties and crystal structure parameters of the polyamide membrane to increase hydrophilicity. By controlling the formation of γ-crystals and adjusting processing parameters, the membrane achieves both strength and improved water permeability, resolving the contradiction between membrane strength and water permeability.
Solution Approach 2:
The invention converts the inherent hydrophobicity of polyamide into a benefit by controlling crystal formation. The γ-crystals create hydrophilic pathways that attract water, transforming the potentially harmful hydrophobic property into a beneficial feature that enhances water permeability while maintaining strength.
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 membrane achieves improved liquid permeability while maintaining bubble point, solute rejection rate, and molecular weight cutoff, leading to increased productivity, energy savings, and reduced production costs in various industries.
Implementation Method 1
employing the thermally-induced phase separation method and non-solvent-induced phase separation method
Implementation Method 2
The membrane achieves improved liquid permeability while maintaining bubble point, solute rejection rate, and molecular weight cutoff
Data Source
AI summary
The purpose of the present invention is to provide a polyamide porous membrane that makes it possible to improve liquid permeability while suppressing deterioration of membrane separation performance. A polyamide porous membrane according to the present invention is formed from a polyamide resin, wherein in structural analysis by X-ray diffraction, the ratio of γ crystals with respect to the total amount of a crystals and γ crystals is not less than 38%.