Hollow Fiber Membrane Composition for High Flux and Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for producing hollow fiber porous membranes result in products with low porosity, poor hydrophilicity, and low water flux, often requiring high spinning temperatures and large amounts of organic solvents, which increase production costs and environmental concerns.
Innovation Solution
A composition comprising a polymer matrix, an organic mixed solution, and a water-soluble substance, where the organic mixed solution is stable at the melting temperature of the polymer matrix, promoting microphase separation and porosity, and a low molecular weight water-soluble particle or polymer, allowing for melt spinning at a controlled temperature with easy washing, resulting in high-strength and high-flux membranes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional methods use hard elastic polymers like PP and PE to produce hollow fiber porous membranes, then the membranes have good mechanical strength, but they exhibit low porosity, poor hydrophilicity, and low water flux
Solution Approach 1:
The invention uses composite materials by combining PVDF polymer matrix with water-soluble pore-forming agents (PVA, PEG, or starch). This composite approach allows the membrane to simultaneously achieve mechanical strength from PVDF and high porosity/water flux from the water-soluble additives that create interconnected pore structures after dissolution.
Solution Approach 2:
The invention employs porous materials by incorporating water-soluble pore-forming agents (PVA, PEG, or starch) that dissolve during the membrane formation process, creating permanent porous structures. These porous structures significantly increase porosity and water flux while maintaining mechanical integrity through the PVDF matrix.
2Quantity of substance
If a polymeric pore forming agent is used with a surfactant and liquid insoluble to the polymer, then the membrane can achieve permeable micropores, but organic solvents like isopropyl alcohol and ethanol must be used for washing, increasing production cost and causing secondary pollution
Solution Approach 1:
The invention converts the harmful effect of using organic solvents into a benefit by selecting water-soluble pore-forming agents (PVA, PEG, or starch) that can be removed using only water for washing. This eliminates the need for expensive and environmentally harmful organic solvents like isopropyl alcohol and ethanol, reducing both production costs and secondary pollution while maintaining permeable micropore structures.
3Ease of manufacture
If water-soluble polymers like polyoxyethylene and PVDF are mixed with a diluent, then the mixture can be melted, but the compatibility difference and viscosity difference at spinning temperature make it very difficult to form a uniform porous structure
Solution Approach 1:
The invention applies parameter changes by carefully controlling the composition ratios of PVDF to water-soluble additives (PVA, PEG, or starch) within specific ranges (95:5 to 80:20). This parameter optimization, combined with controlling the spinning temperature and cooling rate, ensures uniform phase separation and formation of homogeneous porous structures despite the inherent viscosity differences between components.
4Ease of manufacture
If conventional methods require high spinning temperatures (60°C or more higher than the melting point of the resin), then the polymer can be melted and extruded, but the organic liquid used is a poor solvent at room temperature, worsening spinnability and requiring large amounts that increase cost
Solution Approach 1:
The invention uses water as an intermediary solvent that serves multiple functions: it acts as a good solvent for the water-soluble pore-forming agents (PVA, PEG, or starch) at spinning temperature, enables proper phase separation, and allows for easy washing without requiring large amounts of organic liquids. This eliminates the need for high spinning temperatures and poor solvents, improving spinnability and reducing costs.
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 high-strength and large-flux hollow fiber membranes with reduced production costs and environmental impact, featuring a simple and cost-effective process suitable for industrialization.
Implementation Method 1
promoting microphase separation and porosity
Implementation Method 2
melt spinning at a controlled temperature
Implementation Method 3
easy washing
Data Source
AI summary
A composition for preparation of a hollow fiber porous membrane including 40-60 wt. % a polymer matrix, 20-30 wt. % an organic mixed solution, and 20-40 wt. % a water-soluble substance. The polymer matrix is a polymer capable of dissolving in an organic solvent and melt processing. The organic mixed solution is a mixture comprising 60-90 wt. % a first liquid soluble to the polymer matrix and 10-40 wt. % a second liquid insoluble to the polymer matrix. The water-soluble substance is a water-soluble polymer, a low molecular weight water-soluble particle, or a mixture thereof. A method for producing the hollow fiber porous membrane using the composition including a) preparing the organic mixed solution, b) mixing the components of the composition, c) applying melt spinning, d) drawing, and e) washing. The hollow fiber membrane has high strength, large flux, and low cost.