Self-healing Thermoset Composite with Shape Memory Fibers
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Solution Overview
Problem
Current self-healing systems for thermoset polymers are ineffective in autonomously and repeatedly healing structural-length scale damage, such as impact damage, without altering the material's physical or mechanical properties, and often leave voids that affect mechanical properties.
Innovation Solution
A polymeric composition utilizing strain-hardened shape memory polymer fibers that narrow and close cracks through tension programming, followed by molten thermoplastic particles diffusing into the crack to achieve molecular-scale healing without external confinement, mimicking the biological healing process of human skin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional self-healing systems are used for thermoset polymers, then healing capability is provided, but the material's physical or mechanical properties are altered and voids are left that affect mechanical properties
Solution Approach 1:
The patent utilizes temperature as a critical parameter to control the healing process. The thermoplastic particles are heated above their melting point to enable flow and diffusion into cracks, then cooled to solidify and restore mechanical properties. This parameter change approach allows healing without permanent alteration of the base thermoset polymer's mechanical properties.
Solution Approach 2:
The invention exploits the phase transition of thermoplastic particles between solid and liquid states. When heated above their melting point, the particles transition to liquid form, flow into cracks, and upon cooling, solidify to heal the damage. This phase transition mechanism enables effective healing while maintaining the structural integrity and mechanical properties of the thermoset polymer matrix.
2Manufacturing precision
If external confinement is used to close cracks, then crack closure is achieved, but the system becomes more complex and requires additional components
Solution Approach 1:
The patent employs self-service principles where the thermoplastic particles autonomously respond to thermal stimulation by melting and flowing into cracks without requiring external confinement structures. The healing agents are pre-dispersed within the polymer matrix and activate automatically when heated, eliminating the need for complex external confinement systems.
Solution Approach 2:
The thermoplastic particles serve as intermediary healing agents that mediate the crack closure process. Instead of using complex mechanical confinement systems, the patent introduces thermoplastic particles as a intermediate substance that flows into and fills cracks when melted, then solidifies to close and heal the damage.
3Reliability
If thermoplastic particles are heated above melting point, then molecular-scale healing occurs, but energy consumption increases
Solution Approach 1:
The patent applies partial heating action by targeting only the regions containing thermoplastic particles and cracks for heating, rather than heating the entire structure uniformly. The thermoplastic particles are heated above their melting point locally to enable healing, while the rest of the thermoset polymer matrix remains at lower temperatures, reducing overall energy consumption.
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 composition enables repeated, autonomous healing of macroscopic cracks and molecular-scale damage in thermoset polymers, maintaining the material's integrity and mechanical properties without leaving voids, thereby extending the service life of polymer composite structures.
Implementation Method 1
shape memory polymer capable of shrinking upon exposure to additional energy
Implementation Method 2
heating an area comprising the damage or wound to a temperature above the glass transition temperature of the shape memory polymer (SMP) fiber
Implementation Method 3
heating an area comprising the damage/wound to a temperature above the melting temperature of the thermoplastic material
Implementation Method 4
the thermoplastic molecules diffuse into the fractured conventional thermoset polymer matrix and establish molecular entanglement
Data Source
AI summary
Provided is a method for altering properties of tension programmed fibrous shape memory polymer. The method can include applying a protective coating to the tension programmed shape memory polymer, then applying a supportive coating to the tension programmed shape memory polymer to form a coated fiber. The protective coating avoids contact between the shape memory polymer and chemicals used in the supportive coating that can decompensate the shape memory polymer.