• Journal of radiological science and technology
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• v.23 no.2
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• pp.33-37
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• 2000

The authors fabricated ultrasonic transducer with PVDF[poly(vinylidene fluoride)] piezoelectric polymer film. When impulse waves were applied to the PVDF ultrasonic transducer, the dependence of the response properties on the backing material with copper was investigated through not only theoretical calculations using Mason's equivalent circuit but also experimental measurements. The experimental pulse response properties agree with those of the theoretical calculations and the pulses were shorter than those for a PZT transducer. If such short-pulse properties are used in an medical ultrasonic image diagnosis apparatus, the resolution of the apparatus will be improved. When the insertion loss was calculated theoretically to the PVDF ultrasonic transducer, the frequency characteristics of its showed wideband frequency.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.37-43
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• 2001

Polyvinylidenefluoride and Polytetrafluoroethylene have been irradiated by 1 keV Ar+ ion beam in an $O_2$ environment. Hydrophilic functional groups (such as -(C-O)-,-(C=O)-,-(C=O)-O- and so on) were formed on fluoropolymers. Contact angles of water to PVDF were reduced from $75^{\circ}$ to $31^{\circ}$. Re-increase of contact angle was originated from carbonization phase in case of high dose irradiation above $1{\times}10^{16} Ar^+cm^2$. Contact angles to PTFE decreased at low dose irradiation and were exaggerated to about $140^{\circ}$ due to cone type surface at high dose irradiation. Hydrophilic functional groups have played an important role on adhesion between metal and fluoropolymers by acid-base interaction and chemical bond formation. Adhesion of Pt/PVDF was enhanced by acid-base interaction because Pt is inert metal. Chemical bond formation between Cu and PTFE could enlarge the adhesion strength of Cu/PTFE.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.3
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• pp.268-274
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• 2004

Patch type piezo-polymer sensors for smart structures were experimented to detect elastic wave. The pencil lead braking test was performed to analyze the characteristics of patch-type piezo-polymer sensors such as polyvinyliden fluoride (PVDF) and polyvinylidene fluoride trifluorethylene (P(VDF-TrFE)) for several test specimens with various elastic wave velocities and acoustical impedances. The characteristics of the patch-type piezo-polymer sensor were compared with the commercial PZT acoustic emission (AE) sensor. The vacuum grease and epoxy resin were used as a couplant for the acoustic impedance matching between the sensor and specimen. The peak amplitude of elastic wave increased as the diameter of piezo-film and acoustical impedance of the specimen increased. The frequency detection range of the piezo-film sensors decreased with increasing diameter of the piezo-film sensor. The P(VDF-TrFE) sensor was more sensitive than the PVDF sensor.

• Journal of Adhesion and Interface
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• v.2 no.1
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• pp.18-22
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• 2001

Surface morphology of [poly(vinylidene fluoride)/poly(methyl methacrylate)] (PVDF/PMMA) was investigated on the basis of atomic force microscopy and differential scanning calorimeter measurements. The surface of (PMMA/PVDF) and (H14-PMMA/PVDF) blend films was fully composed with PVDF crystals. Although the difference of surface free energy between PMMA and PVDF is increased with increasing carboxyl group content in PMMA, however, in the case of (H24-PMMA/PVDF) blend film surface, the existence of aggregated H-PMMA was observed. It was found that the degree of surface enrichment of the blend is more affected by the magnitude of intermolecular interaction than the surface free energy difference, Besides, the introduction of carboxyl group for miscible (PVDF/PMMA) blend decreased the miscibility in the blend.

• Journal of the Korean Vacuum Society
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• v.8 no.3A
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• pp.194-200
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• 1999

In this paper studied was the piezoelectric properties of the $\beta$-PVDF organic thin films prepared by physical vapour deposition method. The molecular orientation of organic thin films was controlled by the application of an electric field and variation of substrate temperature during the evaporation process. Optimum conditions of manufacturing $\beta$-PVDF organic thin film by physical vapor deposition method is to keep at the substrate temperature of $80^{\circ}C$, at the applied electric field of 142.8 kV/cm. The voltage output coefficient increased from 1.39 to 7.04V increasing the force moment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.261-264
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• 2000

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li polymer battery. This paper describes temperature dependence of conductivity, impedance spectroscopy, electrochemical properties of PAN/PVDF electrolytes as a function of a mixed ratio. PAN/PVDF based polymer electrolyte films were prepared by thermal gellification method of preweighed PAN/PVDF, plasticizer and Li salt. By adding PVDF and as a function of plasticizer mixed ratio to PAN-LiClO4 electrolyte, its conductivity was higher than that of PAN-$LiClO4_4$ electrolyte. The conductivity of PAN/PVDF electrolytes was $10^{-3}S/cm$. $10PAN10PVDFLiClO_4PC_5EC_5$ electrolyte shows the better conductivity of the others. Steady state current method and ac impedance used for the determination of transference numbers in PAN/PVDF electrolyte film. The transference number of $10PAN10PVDFLiClO_4PC_5EC_5$ electrolyte is 0.45.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.1
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• pp.53-59
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• 2001

Surfaces of PTFE and PVDF were modified by ion-assisted reaction (IAR) in which 1 keV $Ar^{+}$ ions were irradiated on the surface of the polymer with varying ion dose in an oxygen gas environment, and Cu, Pt, Al and Ag thin films were deposited on the modified polymers. Wettability of the modified polymers was largely improved by the formation of hydrophilic groups due to chemical reaction between polymer surface and the oxygen gas during IAR. The change in wettability in the modified polymers was also related to the change in surface morphology and roughness. Adhesion between metal films and polymers modified by IAR was significantly improved, so that no detachment was possible in the $Scotch^{TM}$ tape test. The increase of adhesion strength between the metal film and the modified PVDF was mainly attributed to the formation of hydrophilic groups, which interacted with the metal film. In the case of the modified PTFE, the enhanced adhesion to metal film could be explained by the change in surface morphology together with the formation of hydrophilic groups. The electrical properties of the metal films on the modified polymers were also investigated.

• Journal of Sensor Science and Technology
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• v.20 no.2
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• pp.114-117
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• 2011

A thick 25 ${\mu}m$ thickness poled P(VDF/TrFE) film pyroelectric infrared ray sensor has been fabricated and then thin 1.6 ${\mu}m$ thickness P(VDF/TrFE) film pyroelectric infrared ray sensor has been fabricated also. These thick and thin P(VDF/TrFE) film pyroelectric infrared ray sensor was mounted in TO-5 housing to detect infrared light of 5.5 ~ 14 ${\mu}m$ wavelength for human body detecting with each other. The noise output voltage of the thick P(VDF/TrFE) film pyroelectric infrared ray sensor were 380 mV and NEP(noise equivalent power) is $3.95{\times}10^{-7}$ W which is the similar value with the commercial pyroelectric infrared ray sensor using ceramic materials as a sensing material. The NEP and specific detectivity $D^*$ of the thin P(VDF/TrFE) film pyroelectric infrared ray sensor were $2.13{\times}10^{-8}$ W and $9.37{\times}106$ cm/W under emission energy of 13 ${\mu}W/cm^2$ respectively. These result caused by lower thermal diffusion coefficient of a thin 1.6 ${\mu}m$ thickness PVDF/TrFE film than the thick 25 ${\mu}m$ thickness poled P(VDF/TrFE) film pyroelectric infrared ray sensor.

• Polymer(Korea)
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• v.35 no.2
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• pp.130-135
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• 2011

Along with the fast development of electronics, the demands of portable electronics and wireless sensors are growing rapidly. The need for self-powering materials capable of powering the electrical devices attached to them is increasing, The piezoelectric effect of polyvinylidene fluoride (PVDF) can be used for this purpose. PVDF has a special crystal structure consisting of a ${\beta}$-phase that can produce piezoelectricity. In this paper, multilayer PVDF films were fabricated to increase the ${\beta}$-phase content. A solution of 10% concentration N;N-dimethylacetamide (DMAc) in PVDF (PVDF/DMAc) was used to fabricate the films via spin coating technique with the following optimum process parameters: a spin rate of 850 rpm, spin time of 60 s, drying temperature of $60^{\circ}C$, and drying time of 30 min, Compared with single-layer PVDF films, the multilayer films exhibited higher ${\beta}$-phase content. The ${\beta}$-phase content of the films increased gradually with increasing number of layers until 4, Maximum ratio of ${\beta}$-phase content was 7.72.

• Polymer(Korea)
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• v.37 no.2
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• pp.177-183
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• 2013

Surface properties such as morphology, crystalline structure, and chemical composition of poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend coatings prepared by dispersion coating on poly(ethylene terephthalate) (PET) film have been investigated. It was observed that the surface properties were greatly influenced by the coating temperature and blend composition according to SEM, ATR-FTIR and XPS analysis. The typical surface morphology of ${\alpha}$-crystalline structure of PVDF could be observed when the coating temperature was lower than $120^{\circ}C$ or the amount of PVDF was higher than 80 wt% in the blend. Otherwise, the crystalline structure was changed from ${\alpha}$-crystal to ${\gamma}$-crystal or amorphous state. Based on the XPS analysis, the surface segregation of PVDF chains in the blend coating was confirmed.