WO2007073184A1 - Load sensor - Google Patents
Load sensor Download PDFInfo
- Publication number
- WO2007073184A1 WO2007073184A1 PCT/NL2006/050307 NL2006050307W WO2007073184A1 WO 2007073184 A1 WO2007073184 A1 WO 2007073184A1 NL 2006050307 W NL2006050307 W NL 2006050307W WO 2007073184 A1 WO2007073184 A1 WO 2007073184A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- load sensor
- composite
- sensor according
- pzt
- polymer matrix
- Prior art date
Links
- 239000002131 composite material Substances 0.000 claims abstract description 27
- 229920000642 polymer Polymers 0.000 claims abstract description 13
- 239000000843 powder Substances 0.000 claims abstract description 13
- 239000011159 matrix material Substances 0.000 claims abstract description 11
- 239000007788 liquid Substances 0.000 claims abstract description 10
- 229920006038 crystalline resin Polymers 0.000 claims abstract description 9
- 229910010293 ceramic material Inorganic materials 0.000 claims abstract description 7
- 239000002245 particle Substances 0.000 claims description 9
- 239000000178 monomer Substances 0.000 claims description 5
- UEXCJVNBTNXOEH-UHFFFAOYSA-N Ethynylbenzene Chemical group C#CC1=CC=CC=C1 UEXCJVNBTNXOEH-UHFFFAOYSA-N 0.000 claims description 4
- 239000000919 ceramic Substances 0.000 claims description 4
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 claims description 2
- PEEHTFAAVSWFBL-UHFFFAOYSA-N Maleimide Chemical compound O=C1NC(=O)C=C1 PEEHTFAAVSWFBL-UHFFFAOYSA-N 0.000 claims description 2
- FJKROLUGYXJWQN-UHFFFAOYSA-N 4-hydroxybenzoic acid Chemical compound OC(=O)C1=CC=C(O)C=C1 FJKROLUGYXJWQN-UHFFFAOYSA-N 0.000 description 8
- 230000035945 sensitivity Effects 0.000 description 7
- KAUQJMHLAFIZDU-UHFFFAOYSA-N 6-Hydroxy-2-naphthoic acid Chemical compound C1=C(O)C=CC2=CC(C(=O)O)=CC=C21 KAUQJMHLAFIZDU-UHFFFAOYSA-N 0.000 description 6
- 239000002033 PVDF binder Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229920001169 thermoplastic Polymers 0.000 description 4
- 229920001187 thermosetting polymer Polymers 0.000 description 4
- 239000004416 thermosoftening plastic Substances 0.000 description 4
- 238000004132 cross linking Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229940090248 4-hydroxybenzoic acid Drugs 0.000 description 2
- 239000004593 Epoxy Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000003623 enhancer Substances 0.000 description 1
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000010137 moulding (plastic) Methods 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- -1 phenylethynyl end groups Chemical group 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 238000007669 thermal treatment Methods 0.000 description 1
- 239000004634 thermosetting polymer Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/16—Measuring force or stress, in general using properties of piezoelectric devices
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
- H10N30/852—Composite materials, e.g. having 1-3 or 2-2 type connectivity
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
- H10N30/853—Ceramic compositions
- H10N30/8548—Lead based oxides
- H10N30/8554—Lead zirconium titanate based
Definitions
- the invention relates to a load sensor comprising a polymer matrix and a piezo-ceramic material embedded in the polymer matrix, which together form a composite.
- PZT particles Such a composite formed from a polymer matrix com- prising a ceramic powder in the form of PZT particles having a size from 5-10 ⁇ m, is known from the article Poling Flexible Piezoelectric Composites, G. Sa-Gong, A. Safari, S.J. Jang, R.E. Newnham, Ferroelectrics Letters, 5, (1986), 131- 142.
- PZT particles are understood to be particles of lead zirconium titanate.
- the known composite provides a piezoelectric material which has an unsatisfactory piezoelectric sensitivity, a limited thermal stability as well as a limited chemical stability and insufficient ductility.
- An important drawback of the known composite is further that it is not suitable for post-formation in the sense of a plastic deformability that makes the material suitable for application in a form to be determined later, without the piezo-electric properties being affected by the post-formation.
- the European patent application EP-A-I 020 487 relates to an electroceramic product that is readily mouldable without complicated final processing, and to this end comprises a thermoplastic or thermosetting polymer matrix, in which piezo-ceramic particles are dispersed. In particular embodiments the possibility of using different types of ceramic particles is mentioned, or the application of a bonding enhancer (silane coupling) .
- the object of the invention is to provide a load sensor possessing high sensitivity as well as being thermo- chemically stable, resistant to ionising radiation and that, in addition, is post-formable.
- the load sensor according to the invention is characterised by one or several of the appended claims .
- the load sensor is characterised in that the polymer matrix of the composite is a liquid crystalline resin.
- liquid crystalline resin possesses the ability to behave like a thermoplast, and after processing at sufficiently high temperatures, as ther- mosetter. This provides both the freedom to form according to choice, as well as providing form-retention during a later thermal treatment.
- the use of a PZT powder, in an amount of 30-60% by volume of the composite, to form the piezo-ceramic material provides an excellent piezoelectric voltage sensitivity, as a G33-value of above 30 mVm/N clearly shows.
- the composite has an excellent chemical and thermal stability while maintaining the plastic moulding properties explained above.
- the post-formability referred to makes it possible to fabricate a load sensor from the composite, which load sensor, by way of a thermoplastic treatment step, receives its shape in accordance with the geometry of the object to which the sensor is to be attached. This also has a positive influence on the effective sensitivity of the load sensor with regard to detecting dynamic, mechanical deformations, while the measure also extends the life.
- An optimal combination of piezoelectric sensitivity and mechanical properties of the material is obtained when 40-50% by volume of the composite is PZT powder.
- a suitable choice of PZT powder is a PZT powder having a particle size in the range from 0.1-10 ⁇ m.
- liquid crystallinity, thermochemical and radiation resistance and a desirable dielectric value can be achieved with a load sensor character- ised in that the liquid crystalline resin is formed on the basis of monomers of HNA and HBA.
- HNA is 6-hydroxy-2-naphtoic acid
- HBA is 4-hydroxybenzoic acid.
- Oligomers composed of these monomers preferably possess thermally reactive end groups ⁇ which, at the desired reaction temperature make it possible to obtain post- formability. This reaction temperature allows cross-linking of the groups to occur, so that the transition from thermo- plastic to thermosetting behaviour becomes adjustable.
- Suitable end groups are preferably selected from the group comprising paraphenylethyl, phenylacetylene, maleimide and acrylate.
- the ratios for the HNA and HBA monomers preferably range from (80 : 20) -(20 : 80).
- the composite serving as basis for the load sensor according to the invention and which comprises a piezo- ceramic material such as PZT embedded in a liquid crystalline resin, may be fabricated in the following manner.
- the PZT material for the fabrication PZT powder is used, having a particle size between 0.1 and 10 ⁇ m and a mean value around 1 ⁇ m.
- the PZT powder has a composition and crystalline structure that is suitable for a sensor application.
- the PZT particles have an aspect ratio of 1 or a value differing therefrom, such as in PZT fibres.
- thermosetting liquid crystalline resin based on 6-hydroxy-2-naphtoic acid (HNA) and 4- hydroxybenzoic acid (HBA) , with reactive phenylethynyl end groups.
- HNA 6-hydroxy-2-naphtoic acid
- HBA 4- hydroxybenzoic acid
- the polymer is obtained via a melting polymerisation.
- the HNA-HBA ratio may be chosen between the ratios 80:20 to 20:80, depending on the desired processing and property profile.
- the mol weights for cross-linking preferably range from between 5000 grams/mol to 9000 grams/mol but good properties are obtained over the entire range of mol weights from 1000- 25000 grams/mol.
- the composite may subsequently be fabricated by mixing the PZT powder and the liquid crystalline resin and forming the mixture, under pressure and at elevated temperature, into the desired composite.
- pressure and temperature may be used in order to obtain a non-porous sensor film.
- the maximum temperature and lingering time determine the degree of cross-linking and is an important control parameter for the final mechanical and thermochemical properties.
- the ideal temperature depends on the composition of polymers and the desired property profile.
- composition of the composite may be varied within reasonable limits, but the PZT fracture for optimal combinations of sensitivity and mechanical properties typi- cally ranges from approximately 40-50% by volume.
- the poling of the sensor composite film occurs after the application of a metallic layer on both sides of the film at a voltage in the order of 10-15 kV/mm at a temperature of approximately 200 0 C. Poling may occur in air or in an oil bath.
- the necessary poling time should be chosen such that a maximum voltage sensitivity is obtained. A typical poling time is 30-40 minutes.
- PZT-LCR sensor composite according to the invention
- PVDF polyvinylidene fluoride
- Irradiation stability moderate moderate no significant Co-60 gamma source (formation of deterioration at volatile gasses) 80 kGy
Abstract
The invention relates to a load sensor comprising a polymer matrix and a piezo-ceramic material such as PZT, em¬ bedded in the polymer matrix, which together form a compos¬ ite, wherein the polymer matrix is a liquid crystalline resin, and wherein the piezo-ceramic material is a PZT powder forming 30-60% by volume of the composite, and wherein the PZT powder forms 40-50% by volume of the composite.
Description
Load sensor
The invention relates to a load sensor comprising a polymer matrix and a piezo-ceramic material embedded in the polymer matrix, which together form a composite.
Such a composite formed from a polymer matrix com- prising a ceramic powder in the form of PZT particles having a size from 5-10 μm, is known from the article Poling Flexible Piezoelectric Composites, G. Sa-Gong, A. Safari, S.J. Jang, R.E. Newnham, Ferroelectrics Letters, 5, (1986), 131- 142. PZT particles are understood to be particles of lead zirconium titanate.
The known composite provides a piezoelectric material which has an unsatisfactory piezoelectric sensitivity, a limited thermal stability as well as a limited chemical stability and insufficient ductility. An important drawback of the known composite is further that it is not suitable for post-formation in the sense of a plastic deformability that makes the material suitable for application in a form to be determined later, without the piezo-electric properties being affected by the post-formation. The European patent application EP-A-I 020 487 relates to an electroceramic product that is readily mouldable without complicated final processing, and to this end comprises a thermoplastic or thermosetting polymer matrix, in which piezo-ceramic particles are dispersed. In particular embodiments the possibility of using different types of ceramic particles is mentioned, or the application of a bonding enhancer (silane coupling) .
The object of the invention is to provide a load sensor possessing high sensitivity as well as being thermo- chemically stable, resistant to ionising radiation and that, in addition, is post-formable.
To this end, the load sensor according to the invention is characterised by one or several of the appended claims .
In a first aspect of the invention, the load sensor is characterised in that the polymer matrix of the composite is a liquid crystalline resin.
By means of this measure, it is possible to simply adjust the processability with respect to postforming the load sensor in accordance with the desired application, so as to realise a controlled transition from a thermoplastic phase to a thermosetting phase.
It is therefore essential for the invention that at low maximum processing temperatures the liquid crystalline resin possesses the ability to behave like a thermoplast, and after processing at sufficiently high temperatures, as ther- mosetter. This provides both the freedom to form according to choice, as well as providing form-retention during a later thermal treatment.
The use of a PZT powder, in an amount of 30-60% by volume of the composite, to form the piezo-ceramic material provides an excellent piezoelectric voltage sensitivity, as a G33-value of above 30 mVm/N clearly shows. The composite has an excellent chemical and thermal stability while maintaining the plastic moulding properties explained above.
The post-formability referred to makes it possible to fabricate a load sensor from the composite, which load sensor, by way of a thermoplastic treatment step, receives its shape in accordance with the geometry of the object to which the sensor is to be attached. This also has a positive influence on the effective sensitivity of the load sensor with regard to detecting dynamic, mechanical deformations, while the measure also extends the life. An optimal combination of piezoelectric sensitivity and mechanical properties of the material is obtained when 40-50% by volume of the composite is PZT powder.
In order to obtain the desirable properties, a suitable choice of PZT powder is a PZT powder having a particle size in the range from 0.1-10 μm.
The desirable properties of liquid crystallinity, thermochemical and radiation resistance and a desirable dielectric value can be achieved with a load sensor character-
ised in that the liquid crystalline resin is formed on the basis of monomers of HNA and HBA. In the context of the present patent application, HNA is 6-hydroxy-2-naphtoic acid and HBA is 4-hydroxybenzoic acid. Oligomers composed of these monomers preferably possess thermally reactive end groups^ which, at the desired reaction temperature make it possible to obtain post- formability. This reaction temperature allows cross-linking of the groups to occur, so that the transition from thermo- plastic to thermosetting behaviour becomes adjustable.
Suitable end groups are preferably selected from the group comprising paraphenylethyl, phenylacetylene, maleimide and acrylate.
The ratios for the HNA and HBA monomers preferably range from (80 : 20) -(20 : 80).
Hereinafter the invention will be further elucidated by way of a possible production process for the composite from which the load sensor is formed.
Description of a process for the fabrication of a composite according to the invention
The composite serving as basis for the load sensor according to the invention, and which comprises a piezo- ceramic material such as PZT embedded in a liquid crystalline resin, may be fabricated in the following manner.
- The PZT material. For the fabrication PZT powder is used, having a particle size between 0.1 and 10 μm and a mean value around 1 μm. The PZT powder has a composition and crystalline structure that is suitable for a sensor application.
The PZT particles have an aspect ratio of 1 or a value differing therefrom, such as in PZT fibres.
- The polymer. A thermosetting liquid crystalline resin based on 6-hydroxy-2-naphtoic acid (HNA) and 4- hydroxybenzoic acid (HBA) , with reactive phenylethynyl end groups. The polymer is obtained via a melting polymerisation. The HNA-HBA ratio may be chosen between the ratios 80:20 to
20:80, depending on the desired processing and property profile. The mol weights for cross-linking preferably range from between 5000 grams/mol to 9000 grams/mol but good properties are obtained over the entire range of mol weights from 1000- 25000 grams/mol.
The composite may subsequently be fabricated by mixing the PZT powder and the liquid crystalline resin and forming the mixture, under pressure and at elevated temperature, into the desired composite. In order to obtain a non-porous sensor film, different combinations of pressure and temperature may be used. The maximum temperature and lingering time determine the degree of cross-linking and is an important control parameter for the final mechanical and thermochemical properties. The ideal temperature depends on the composition of polymers and the desired property profile.
The composition of the composite may be varied within reasonable limits, but the PZT fracture for optimal combinations of sensitivity and mechanical properties typi- cally ranges from approximately 40-50% by volume.
- The poling of the sensor composite film occurs after the application of a metallic layer on both sides of the film at a voltage in the order of 10-15 kV/mm at a temperature of approximately 2000C. Poling may occur in air or in an oil bath. The necessary poling time should be chosen such that a maximum voltage sensitivity is obtained. A typical poling time is 30-40 minutes.
The table below shows a comparison between various properties of the sensor composite according to the invention (PZT-LCR) compared with several known composite material such as PZT-epoxy and PZT-PVDF (PVDF = polyvinylidene fluoride) . This overview shows that with respect to the complete range of the relevant electrical and non-electrical properties, the composite material according to the invention is more successful than, or at least as successful as, the known composite materials, while the composite according to the invention possesses in addition excellent properties with regard to post-formability.
Property PZT- Epoxy PZT- PVDF PZT- LCR
g∞ (sensor) properties 47 mVm/N 36 mVm/N 48 mVm/N (maximum)
Mechanical properties low strength low strength high strength
Stability in water moderate moderate excellent
Chemical stability poor poor excellent in organic solvents
Chemical stability moderate poor excellent in acids
Thermal stability of the system <120°C <100°C <300°C
Thermal stability of the <120°C <100°C <17Q°C piezoelectric effect
Electrical quality factor (QE) at <30 <30 80-100 room temperature
Irradiation stability moderate moderate no significant Co-60 gamma source (formation of deterioration at volatile gasses) 80 kGy
Post-formability absent very limited present and adjustable
Claims
1. A load sensor comprising a polymer matrix and a piezo-ceramic material embedded in the polymer matrix, which together form a composite, characterised in that the polymer matrix is a liquid crystalline resin.
2. A load sensor according to claim 1, characterised in that the piezo-ceramic material is a PZT powder forming 30-60% by volume of the composite.
3. A load sensor according to claim 1 or 2, characterised in that the piezo-ceramic powder forms 40-50% by vol- ume of the composite.
4. A load sensor according to one of the claims 1-3, characterised in that the PZT powder has a particle size in the range from 0.1-10 μm.
5. A load sensor according to one of the preceding claims, characterised in that the liquid crystalline resin is formed on the basis of monomers of HNA and HBA.
6. A load sensor according to claim 5, characterised in that oligomers composed of the monomers possess thermally reactive end groups.
7. A load sensor according to claim 6, characterised in that the end groups are selected from the group comprising paraphenylethyl, phenylacetylene, maleimide and acrylate.
8. A load sensor according to one of the claims 5-8, characterised in that the HNA : HBA ratio is selected in the range (80 : 20) -(20 : 80).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL1030620A NL1030620C2 (en) | 2005-12-08 | 2005-12-08 | Load sensor. |
| NL1030620 | 2005-12-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2007073184A1 true WO2007073184A1 (en) | 2007-06-28 |
Family
ID=36579362
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/NL2006/050307 WO2007073184A1 (en) | 2005-12-08 | 2006-12-07 | Load sensor |
Country Status (2)
| Country | Link |
|---|---|
| NL (1) | NL1030620C2 (en) |
| WO (1) | WO2007073184A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014171822A1 (en) * | 2013-04-16 | 2014-10-23 | Technische Universiteit Delft | Molecular composites based on high-performance polymers and an interpenetrating liquid crystal thermoset |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2188585A (en) * | 1986-03-26 | 1987-10-07 | Polyplastics Co | Polymeric piezoelectric material |
| EP0872719A1 (en) * | 1997-03-12 | 1998-10-21 | Tokai Rubber Industries, Ltd. | Pressure sensor having piezoelectric layer formed by hydrothermal synthesis, and method of producing the same |
| EP1020487A1 (en) * | 1997-09-30 | 2000-07-19 | Ngk Insulators, Ltd. | Plastic-ceramic composite material |
-
2005
- 2005-12-08 NL NL1030620A patent/NL1030620C2/en not_active IP Right Cessation
-
2006
- 2006-12-07 WO PCT/NL2006/050307 patent/WO2007073184A1/en active Application Filing
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2188585A (en) * | 1986-03-26 | 1987-10-07 | Polyplastics Co | Polymeric piezoelectric material |
| EP0872719A1 (en) * | 1997-03-12 | 1998-10-21 | Tokai Rubber Industries, Ltd. | Pressure sensor having piezoelectric layer formed by hydrothermal synthesis, and method of producing the same |
| EP1020487A1 (en) * | 1997-09-30 | 2000-07-19 | Ngk Insulators, Ltd. | Plastic-ceramic composite material |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014171822A1 (en) * | 2013-04-16 | 2014-10-23 | Technische Universiteit Delft | Molecular composites based on high-performance polymers and an interpenetrating liquid crystal thermoset |
| CN105377992A (en) * | 2013-04-16 | 2016-03-02 | 阿罗特罗皮卡科技公司 | Molecular composites based on high-performance polymers and interpenetrating liquid crystal thermoset |
| US9598574B2 (en) | 2013-04-16 | 2017-03-21 | Allotropica Technologies Inc. | Molecular composites based on high-performance polymers and an interpenetrating liquid crystal thermoset |
Also Published As
| Publication number | Publication date |
|---|---|
| NL1030620C2 (en) | 2007-06-11 |
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