Polysiloxane Polyurea Composite for -100°C Flexibility
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Solution Overview
Problem
Elastomeric materials used in low-temperature environments, such as those found in aerospace applications, tend to stiffen and become brittle due to the glass transition temperature of polymeric chains, losing their elastic properties and mechanical strength, and existing solutions face challenges in maintaining flexibility and toughness at subfreezing temperatures while being compatible with solid particulate fillers.
Innovation Solution
A composite material composition comprising a segmented copolymer elastomer with α,ω-(alpha, omega)-dihydroxy terminated polysiloxane, a diisocyanate species, and an amine or hydroxy terminated chain extender, combined with a solid particulate filler and fumed silica, which maintains high flexibility and tensile strength down to -100°C, with a percent elongation greater than 100% and tensile strength greater than 5MPa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If known elastomers are used to maintain flexibility at low temperatures, then the material remains elastic down to low temperatures, but the mechanical strength is reduced
Solution Approach 1:
The patent uses a composite material system consisting of polysiloxane soft segments, polyurea hard segments, and polyether chain extenders to create a segmented copolymer that combines the low-temperature flexibility of polysiloxanes with the mechanical strength of polyurea, while the polyether component prevents phase separation and maintains toughness
2Strength
If particulate fillers in the range of 10-100 nm are added to improve mechanical properties, then the mechanical properties are enhanced, but the material becomes harder to process and apply
Solution Approach 1:
The patent changes the size parameter of particulate fillers from nanometer scale (10-100 nm) to micrometer scale (1-100 μm), which reduces the filler's impact on polymer chain mobility and processing difficulty while still providing reinforcement and functional benefits
3Strength
If polyether compounds are used as intermediate segments to improve mechanical properties, then the mechanical properties are enhanced, but the low temperature elastic range is reduced
Solution Approach 1:
The patent uses polyether compounds as intermediary chain extenders that connect polysiloxane soft segments and polyurea hard segments, where the polyether acts as a flexible bridge that prevents phase separation and maintains low-temperature elasticity while enabling mechanical property enhancement
4Adaptability or versatility
If elastomers are formulated with high levels of solid fillers to add functionality, then additional functionality is achieved, but the material becomes difficult to process and apply
Solution Approach 1:
The patent changes the size parameter of solid fillers to micrometer scale (1-100 μm), which reduces the filler's impact on viscosity and processability while still providing reinforcement and functional benefits, allowing high levels of filler incorporation without sacrificing ease of manufacture
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 solution provides a flexible and tough composite material that maintains mechanical properties at extremely low temperatures, outperforming existing materials by maintaining high elongation and tensile strength, even with high loading levels of solid particulate fillers, and is suitable for aerospace applications.
Implementation Method 1
Many resins composed of silicones or polyurethanes which are commonly used on aircraft exterior surfaces may undergo this transition at -30°C to -40°C. However, since the temperature at high altitudes is often well below this range, it is desirable to find an alternative that will maintain flexibility at lower temperatures.
Implementation Method 2
The composite material composition has a high flexibility at a temperature of down to about -100 degrees Celsius, has a percent elongation of greater than about 100%, and has a tensile strength of greater than about 5MPa
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2~3
AI summary
There is provided a flexible, low temperature, filled composite material composition and method of synthesizing the composite material composition. The composite material composition has a segmented copolymer elastomer having an α,ω-(alpha, omega)-dihydroxy terminated polysiloxane species, a diisocyanate species, and an amine or hydroxy terminated chain extender. The composite material composition further has a solid particulate filler. The composite material composition has a high flexibility at a temperature of down to about -100 degrees Celsius, has a percent elongation of greater than about 100%, and has a tensile strength of greater than about 5MPa (megapascals).