Electret Sheet Phase Separation Piezoelectric Properties
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Solution Overview
Problem
Existing electret sheets with synthetic resin foamed sheets for piezoelectric applications require complex processes to enhance piezoelectric properties, and there is a need for a method that maintains high sensitivity while simplifying the process.
Innovation Solution
An electret sheet formed by combining two incompatible synthetic resins, such as polypropylene and polyethylene, which are cross-linked using a polyfunctional monomer, creating a phase-separated structure that retains electric charges effectively, enhancing piezoelectric properties without complex processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the size of bubbles in synthetic resin foamed sheet is reduced to improve piezoelectric properties, then higher performance is obtained, but a complicated process must be used
Solution Approach 1:
The invention uses a composite material system consisting of two incompatible synthetic resins (e.g., polypropylene and polyethylene) that naturally form a phase-separated structure. This composite approach creates multiple interfaces that enhance piezoelectric properties without requiring complex bubble reduction processes. The phase-separated morphology provides numerous charge trapping sites at the interfaces between different resin phases.
Solution Approach 2:
The invention changes the fundamental parameter of material composition by introducing incompatible synthetic resins with different glass transition temperatures and chemical properties. This parameter change creates a self-organizing phase-separated structure that inherently provides the desired piezoelectric enhancement, eliminating the need for complex processing to reduce bubble size.
2Reliability
If electric charges are injected into synthetic resin sheet to electrify it, then piezoelectric properties are enhanced, but charge retention and stability are insufficient without proper structural design
Solution Approach 1:
The invention creates localized regions of high charge retention capability at the interfaces between incompatible synthetic resin phases. These interface regions have unique electrical properties that differ from the bulk material, providing preferential sites for charge trapping and retention. The local quality enhancement at interfaces solves the charge retention problem without affecting the entire material uniformly.
Solution Approach 2:
The composite structure of incompatible synthetic resins creates a multi-phase system with numerous internal interfaces. These interfaces act as charge trapping sites, significantly improving charge retention. The different electrical properties of each resin phase contribute to stabilizing the injected charges, preventing their rapid dissipation.
3Reliability
If two incompatible synthetic resins are used to form phase separated structure, then charge retention is improved, but manufacturing complexity increases
Solution Approach 1:
The incompatible synthetic resins automatically self-organize into a phase-separated structure during processing due to their thermodynamic incompatibility. This self-service mechanism eliminates the need for additional processing steps to create the desired morphology. The phase separation occurs spontaneously based on the inherent immiscibility of the resin components, simplifying manufacturing while achieving the charge retention goal.
Solution Approach 2:
By selecting synthetic resins with sufficiently different chemical compositions and glass transition temperatures, the invention ensures spontaneous phase separation. This parameter-based approach (choosing resins with large compositional differences) makes the phase-separated structure form naturally during standard processing, avoiding complex manufacturing steps while achieving improved charge retention.
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 electret sheet achieves high piezoelectric properties with improved charge retention and stability, allowing for efficient electric responses to external forces, suitable for applications like acoustic pickups and pressure sensors.
Implementation Method 1
the synthetic resin sheet comprises two types of synthetic resins incompatible with each other, and that these synthetic resins form a phase separated structure
Implementation Method 2
these synthetic resins form a phase separated structure and are cross-linked through a polyfunctional monomer
Implementation Method 3
An electret is a material having thereinside a permanent electric charge imparted by injecting charges into an insulating polymer material
Implementation Method 4
a foamed sheet made of a synthetic resin exhibits very high piezoelectric properties comparable to those of ceramics when bubble membranes forming the bubbles and their vicinities are electrified
Data Source
AI summary
Provided is an electret having high piezoelectric properties. An electret sheet of the invention is characterized in that it comprises a synthetic resin sheet is electrified by injecting electric charges thereinto, that the synthetic resin sheet comprises two types of synthetic resins incompatible with each other, and that these synthetic resins form a phase separated structure and are cross-linked through a polyfunctional monomer. Therefore, positive and negative charges in an apparently polarized state are present in the interfacial portions between the two types of synthetic resins incompatible with each other. By applying an external force to the electret sheet to deform it, the relative positions of these positive and negative charges are changed, and these changes cause a favorable electrical response. Therefore, the electret sheet has high piezoelectric properties.