Piezoelectric Composite with Thermoplastic Elastomer Matrix
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Solution Overview
Problem
Piezoelectric composites with thermoplastic elastomer matrices face limitations in deformation range and processing flexibility due to the association with non-piezoelectric phases, restricting their electroactive and mechanical properties for applications like energy harvesting in tires.
Innovation Solution
A piezoelectric composite with a thermoplastic elastomer matrix comprising copolymers like styrene/butadiene and styrene/isoprene, where the glass transition temperature of the thermoplastic blocks is lower than the Curie temperature of the piezoelectric inorganic fillers, allowing for enhanced flexibility, elasticity, and increased generation of electrical charges without covalent bonding, enabling easier processing and recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid thermoplastic or thermosetting polymer matrix is used to maximize electroactive performance, then piezoelectric activity is improved, but deformation range and flexibility are restricted
Solution Approach 1:
The patent uses a composite material system combining piezoelectric ceramic particles (PZT, BaTiO3, Pb1-xLaxZr1-yTiyO3) with a thermoplastic elastomer matrix (SBS, SIS, SBIS copolymers). This composite structure allows the piezoelectric particles to provide electroactive performance while the elastomer matrix provides flexibility and large deformation capability, resolving the contradiction between rigidity for piezoelectric activity and flexibility for deformation range.
Solution Approach 2:
The patent changes the matrix material parameters from rigid thermoplastics/thermosets to thermoplastic elastomers with specific glass transition temperatures (Tg) lower than the Curie temperature (Tc) of the piezoelectric particles. This parameter change enables the matrix to remain flexible at operating temperatures while maintaining piezoelectric particle stability, thus improving both deformation range and preserving piezoelectric activity.
2Stability of the object's composition
If a thermosetting or thermoplastic matrix is used, then structural stability is improved, but processing flexibility and recyclability are reduced
Solution Approach 1:
The patent selects thermoplastic elastomers with specific glass transition temperatures (Tg) lower than the Curie temperature (Tc) of the piezoelectric particles. This parameter selection allows the matrix to be processed above its Tg (when flexible and moldable) and used below its Tg (when stable), providing both processing flexibility and structural stability. The material can be reheated and reprocessed multiple times, enabling recyclability while maintaining stability during use.
3Ease of repair
If piezoelectric inorganic fillers are dispersed without covalent bonding to the matrix, then ease of recycling is improved, but interfacial adhesion and mechanical strength may be reduced
Solution Approach 1:
The patent uses the temperature-dependent properties of thermoplastic elastomers to achieve both easy recycling and good interfacial adhesion. During processing above Tg, the softened matrix naturally wets and adheres to piezoelectric particle surfaces. During use below Tg, the matrix provides sufficient mechanical strength. The absence of covalent bonds allows for easy separation and recycling, while the physical adhesion during the processing window ensures adequate interfacial bonding.
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 composite exhibits improved electroactive and mechanical properties, including greater flexibility, impact resistance, and efficient electrical charge generation, with the ability to operate effectively at various deformation levels and temperatures, making it suitable for energy harvesting applications.
Implementation Method 1
Piezoelectricity occurs in materials such as crystals, certain semi-crystalline polymers and piezoelectric ceramics. This physical phenomenon corresponds to the appearance of an electrical polarization induced by an external mechanical deformation.
Implementation Method 2
a piezoelectric composite makes it possible to maximize the electroactivity of the polymer matrix, but generally this association also restricts its deformation range
Implementation Method 3
the glass transition temperature, Tg, of each thermoplastic block of the thermoplastic elastomer (TPE) is lower than the Curie temperature, Tc, the lowest of the piezoelectric inorganic charges
Data Source
Figure 1
AI summary
The present invention relates to a piezoelectric composite comprising a polymer matrix and inorganic piezoelectric fillers in the form of particles dispersed in the polymer matrix, but not bound to the polymer matrix, characterised in that: the polymer matrix comprises a thermoplastic elastomer (TPE); the glass transition temperature, Tg, of each thermoplastic block of the thermoplastic elastomer (TPE) is less than the lowest Curie temperature, Tc, of the inorganic piezoelectric fillers, and when the thermoplastic blocks have a melting point, Tf, said melting point of each thermoplastic block is also less than the lowest Curie temperature of the inorganic piezoelectric fillers; and the concentration of inorganic piezoelectric fillers is at least 5 vol.-% relative to the total volume of the polymer matrix. The present invention also relates to a method for producing such a piezoelectric composite, a device comprising such a composite, the use thereof and a tyre comprising such a device.