Thermoplastic Polyurethane Blend for Low-Temperature Flex Fatigue
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Solution Overview
Problem
Existing thermoplastic polyurethane compositions struggle to achieve a balance of high flex modulus, low density, and the ability to withstand cyclic deformations, particularly at low temperatures, due to increased hard segment content which leads to higher density and glass transition temperatures.
Innovation Solution
A thermoplastic polyurethane composition is formulated using a blend of polyether polyol and polybutadiene polyol, optionally with a chain extender, to create articles with a flex modulus of at least 160 MPa and the ability to withstand 30,000 low temperature fatigue cycles, while maintaining transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hard segment content is increased to achieve high flex modulus, then flex modulus is improved, but density and glass transition temperature increase resulting in poor low temperature cyclic fatigue behavior
Solution Approach 1:
The patent changes the chemical composition parameters of the polyol component by incorporating polybutadiene polyol with specific molecular weights (200-1000 g/mol) and hydroxyl functionalities (2.0-3.0), which modifies the hard segment characteristics to achieve high flex modulus while maintaining low temperature fatigue resistance
Solution Approach 2:
The patent creates a composite polyol system combining polyether polyol and polybutadiene polyol in specific ratios (40:60 to 90:10), where the polybutadiene component introduces unsaturation and flexibility that improves low temperature cyclic fatigue behavior while the polyether component maintains structural integrity for high flex modulus
2Strength
If hard segment content is increased to achieve high flex modulus, then flex modulus is improved, but density increases making the material undesirably heavy
Solution Approach 1:
The patent optimizes the molecular weight parameter of the polybutadiene polyol component (200-1000 g/mol) to achieve high flex modulus through efficient hard segment formation while minimizing the mass contribution, thereby reducing overall density compared to conventional high hard segment content TPUs
3Strength
If hard segment content is increased to achieve high flex modulus, then flex modulus is improved, but glass transition temperature increases resulting in poor low temperature cyclic fatigue behavior
Solution Approach 1:
The patent modifies the glass transition temperature parameter by incorporating polybutadiene polyol with unsaturation, which introduces flexible segments and lowers the glass transition temperature of the hard segments, enabling the material to maintain flexibility and fatigue resistance at low temperatures while achieving high flex modulus
Solution Approach 2:
The patent creates local flexibility within the hard segments by incorporating polybutadiene units, which have lower glass transition temperatures compared to conventional polyether or polyester units, thereby maintaining overall high flex modulus while improving low temperature performance locally
Data Source
AI summary
The invention relates to an article made from a thermoplastic polyurethane composition having that has high flex modulus, low density, and is capable of withstanding repeated cyclic deformation. The thermoplastic polyurethane composition is formed from the reaction product of a polyol component, which includes a blend of a polyether polyol, such as poly(tetramethylene ether glycol), and polybutadiene diol, a diisocyanate component, and a chain extender component.