Polymer Nanofoam Production via CO2 Saturation and Depressurization
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Solution Overview
Problem
Current methods face challenges in producing polymer nanofoams with nanoscale cell sizes and high cell densities, particularly in increasing cell density from microscale to nanoscale levels, such as 10^12 cells/cm^3 or higher.
Innovation Solution
A method involving immersing a polymer material in carbon dioxide at high pressure and low temperature, followed by depressurization and heating to form polymer nanofoams with nanoscale cell sizes and high cell densities, using polymers like PMMA with specific melt indices and molecular weights, and optionally incorporating non-polymeric additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional carbon dioxide foaming technique is used, then microcellular foam can be generated with cell size less than 10 μm, but it is difficult to achieve nanoscale cell size and high cell density of 10^12-10^16 cells/cm³
Solution Approach 1:
The patent applies parameter changes by carefully controlling the glass transition temperature (Tg) of the polymer material and the foaming temperature to achieve nanoscale cell sizes. Specifically, the polymer's Tg is maintained between -50°C to 100°C, and the foaming temperature is controlled between -30°C to 80°C, which enables the formation of nanoscale cells with sizes of 10 nm to 1000 nm and cell densities of 10^12 to 10^16 cells/cm³, resolving the difficulty of producing nanoscale cells while maintaining ease of manufacture.
2Manufacturing precision
If polymer material with high viscosity is used, then cell size can be reduced to nanoscale, but the melt index would be too low (below 0.1 g/10 min)
Solution Approach 1:
The patent applies parameter changes by optimizing the melt index of the polymer material to be within 0.1 to 10 g/10 min, which balances the viscosity requirements for nanoscale cell formation with processability requirements. This parameter optimization allows the polymer to form nanoscale cells while maintaining sufficient flow characteristics for practical manufacturing, resolving the contradiction between achieving nanoscale cell size and maintaining appropriate melt index.
3Manufacturing precision
If cell density is increased from microscale (10^9 cells/cm³) to nanoscale (10^12-10^16 cells/cm³), then nanoscale characteristics are achieved, but the process complexity and difficulty increase significantly
Solution Approach 1:
The patent applies parameter changes by controlling the glass transition temperature of the polymer and the foaming temperature within specific ranges, which enables achieving high cell densities of 10^12 to 10^16 cells/cm³ through a relatively simple one-step foaming process. This approach avoids the need for complex multi-step processes or specialized equipment, thus resolving the contradiction between achieving high cell density and maintaining process simplicity.
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 effectively produces polymer nanofoams with average cell sizes between 10 nm and 1000 nm and cell densities of 10^12 cells/cm^3 or more, achieving the desired nanoscale characteristics and mechanical properties.
Implementation Method 1
immersing a polymer material in carbon dioxide at a pressure greater than 5 MPa and a temperature of −30° C. to 40° C. to obtain a carbon dioxide-saturated polymer material
Implementation Method 2
the carbon dioxide-saturated polymer material is depressurized to atmospheric pressure. Then, the carbon dioxide-saturated polymer material is heated to form the polymer nanofoam
Data Source
AI summary
A method for producing a polymer nanofoam includes: immersing a polymer material in carbon dioxide at a pressure greater than 5 MPa and a temperature of −30° C. to 40° C. to obtain a carbon dioxide-saturated polymer material, wherein the melt index of the polymer material measured at 230° C. and 3.8 kg is between 0.1 g/10 min and 8.0 g/10 min. Thereafter, the carbon dioxide-saturated polymer material is depressurized to atmospheric pressure, and then the carbon dioxide-saturated polymer material is heated to form the polymer nanofoam.