VDF/TFE Copolymer Molded Article Ferroelectricity
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Solution Overview
Problem
Conventional ferroelectric films made from vinylidene fluoride (VdF)/tetrafluoroethylene (TFE) copolymers face challenges in achieving high mechanical strength, heat resistance, and ferroelectricity due to complex production processes and resulting properties that are insufficient for modern applications.
Innovation Solution
A molded article is produced by crystallizing a melt of VdF/TFE copolymer while elongating it at a rate not lower than the critical elongational strain rate, resulting in nano-oriented β crystals with excellent mechanical strength, heat resistance, and ferroelectricity, with specific composition and crystal size characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional melt crystallization is used to form ferroelectric films, then β crystals can be formed, but the production process becomes complicated requiring stretching, heat setting, and poling steps
Solution Approach 1:
The invention applies preliminary action by introducing a nucleating agent before crystallization to pre-establish the conditions for β crystal formation. This preliminary preparation eliminates the need for subsequent stretching and heat setting steps, as the β crystals form directly during crystallization with the appropriate orientation and structure needed for ferroelectricity
Solution Approach 2:
The invention extracts and removes the complicated stretching and heat setting steps from the production process. By using a nucleating agent during melt crystallization, the process directly produces β crystals with the required properties, taking out the unnecessary intermediate steps that were previously required to achieve ferroelectricity
2Reliability
If stretching and heat setting are applied to improve ferroelectricity, then molecular chain orientation is achieved, but mechanical strength and heat resistance become insufficient
Solution Approach 1:
The invention changes the fundamental parameters of the crystallization process by using a nucleating agent and controlling crystallization conditions to directly form β crystals. This parameter change eliminates the need for aggressive stretching and heat setting that compromise mechanical strength, achieving ferroelectricity through controlled crystallization rather than mechanical deformation
Solution Approach 2:
By preliminarily adding a nucleating agent to promote direct β crystal formation during crystallization, the invention avoids the need for subsequent stretching and heat setting operations. This preliminary action ensures that the molecular chains are properly oriented during crystal formation itself, preserving mechanical strength while achieving the required ferroelectric properties
3Reliability
If high temperature and high pressure melt crystallization is used to improve ferroelectricity, then highly crystallized film is obtained, but the film becomes cloudy and brittle
Solution Approach 1:
The invention changes the crystallization parameters by using a nucleating agent that enables β crystal formation at lower temperatures and pressures. This parameter change avoids the high temperature and pressure conditions that cause cloudiness and brittleness, while still achieving highly crystallized films with excellent ferroelectricity through controlled nucleation and crystal growth
4Reliability
If conventional production steps are used, then ferroelectric film is formed, but surface roughness is poor
Solution Approach 1:
The invention applies preliminary action by adding a nucleating agent before crystallization to ensure uniform and controlled crystal formation. This preliminary preparation promotes homogeneous crystallization that results in smooth surfaces with good finish, eliminating the poor surface roughness associated with conventional stretching and heat setting processes while maintaining excellent ferroelectric properties
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 resulting molded article exhibits improved mechanical strength, heat resistance, surface roughness, and ferroelectricity, with enhanced properties such as high elastic modulus, remanent polarization, and coercive field, making it suitable for various applications including piezoelectric films and pyroelectric sensors.
Implementation Method 1
crystalizing a melt of the VdF/TFE copolymer while elongating it at a rate not lower than the critical elongational strain rate
Implementation Method 2
crystallizing a melt of the VdF/TFE copolymer
Data Source
Figure 1~2
Figure 3(a)~3(b)
Figure 4(a)~4(c)
AI summary
The invention provides a molded article having excellent mechanical strength, heat resistance, surface roughness, and ferroelectricity. The molded article contains a crystal of a vinylidene fluoride/tetrafluoroethylene copolymer. The crystal is a β crystal and is a nano-oriented crystal that has a size of 100 nm or smaller. The molded article has an arithmetic average roughness of 3.0 µm or lower.