• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
• /
• pp.489-491
• /
• 1987

It has been shown that the thermally stimulated current technique can be one of the most powerful methods for evaluating the electrical properties. An unstretched $\alpha$-form specimen of corona-charged, 50[${\mu}m$],t Polyvinylidene Fluoride shows four TSC peaks designated $\delta}$, $\gamma$, $\beta$ and $\alpha$ in assending order of temperature in temperature range $-100{\sim}200^{\circ}C$. The $\delta$, $\gamma$ peaks may be attributed to the dipolar depolarization in the amorphous regions and $\beta$, $\alpha$ peaks are associated with the detrap from trapped carriers in the crystalline regions.

• 대한전기학회논문지
• /
• 제37권3호
• /
• pp.163-170
• /
• 1988

In order to investigate the mechanism of pyroelectricity on polyvinylidene fluoride film, the observations were carried out on the characteristics of infrared spectra, thermally stimulated current and pyroelectric current. As the results obtained from the study, it was concluded that the origin for thermally stimulated current exhibited above room temperature can be attributed to hole injected from anode during poling process. Futhermore it is clarified also that the origin of pyroelectricity observed on the specimen concerned is to spontaneous polarization of CF dipole attached to molecular chain segment, however, the fraction of spontaneous polarization is largely influenced by the amount of hole injected from anode.

• E2M - 전기 전자와 첨단 소재
• /
• 제1권3호
• /
• pp.261-268
• /
• 1988

본 논문에서는 두께 50[.mu.m]의 미연신 .alpha.형 폴리비닐덴 후로라이드 필름을 시료로 선정, .+-.4~.+-.6[kV]사이의 코로나대전 전압을 인가하여 얻은 코로나 일렉트렛트로 부터 온도 범위 -100[.deg.C]-100[.deg.C] 사이에서 열자격전류를 측정한 결과, 저온으로 부터 .delta., ..gamma., .betha. 및 .alpha.인 4개의 TSC 피크를 얻었다. 이들 피크의 기원을 정성적으로 고찰한 결과, .delta., .gamma.피크는 비정질 영역에서 카보닐기, 주쇄 및 극성기들에 의한 쌍극자의 탈분극으로 또 70[.deg.C]부근에서 관측된 .betha.피크는 비정질 영역 또는 비정질과 결정질의 경계면에서 전극으로 부터 공간전하의 탈트랩으로 그리고 180[.deg.C]근방에서 관측된 .alpha.피크는 결정영역에 깊이 트랩된 캐이어들의 탈트랩으로 각각 피크가 나타나는 것으로 사료된다. .delta., .gamma., .betha.및 .alpha.인 4개의 TSC 피크에 대하여 초기 상승법으로 얻은 활성화 에너지는 각각 0.54[eV], 0.24[eV], 0.99[eV] 및 1.26[eV]를 얻었다.

• Bulletin of the Korean Chemical Society
• /
• 제32권1호
• /
• pp.145-148
• /
• 2011

The thermal behavior of lithiated Si anodes has been investigated using differential scanning calorimetry (DSC). In particular, the effect of Si particle size on the thermal stability of a fully lithiated Si electrode was investigated. For DSC measurements, a lithiated Si anode was heated in a hermetically sealed high-pressure pan with a polyvinylidene fluoride (PVDF) binder and a 1 M $LiPF_6$ solution in an ethylene carbonate (EC)-diethyl carbonate (DEC) mixture. The thermal evolution around $140^{\circ}C$ increases with lithiation and with decreasing particle size; this phenomenon is attributed to the thermal decomposition of the solid electrolyte interface (SEI) film. Exothermic peaks, following a broad peak at around $140^{\circ}C$, shift to a lower temperature with a decrease in particle size, indicating that the thermal stability of the lithiated Si electrode strongly depends on the Si particle size.

• 한국산학기술학회논문지
• /
• 제15권11호
• /
• pp.6399-6405
• /
• 2014

오늘날 작업능률 및 운용효율의 향상을 위해 장비의 대형화 추세가 진행되고 있으나 이와 더불어 사고 발생 시에는 많은 인명 피해와 함께 크나큰 경제적인 손실을 초래하게 되어 대형장비의 안전성 문제에 대하여 많은 연구가 진행되고 있다. 대형구조물의 안전성 감시를 위해 외부의 부하에 따른 구조물의 변형은 스트레인게이지로, 순간적인 충격에 의한 진동은 가속도 센서를 이용한다. 본 연구에서는 고분자 압전 필름센서인 PVDF(PolyVinyliDene Fluoride)를 이용하여 구조물의 변형에 대한 측정뿐만 아니라 충격에 대해서도 민감하게 반응하여 하나의 센서로 부하와 충격을 모두 검출하여 산업적 효율성과 실효성 향상을 도모하였다. 개발된 센서는 스트레인 게이지의 출력값에 대해 14% 이내의 오차를 나타내고 가속도 센서와는 충격에 대해 동일한 패턴의 충격신호를 나타내었다.

• 한국진공학회지
• /
• 제8권2호
• /
• pp.93-101
• /
• 1999

The purposed of this paper is to investigate the electrical and thermal stability of Polyvinylidene fluoride(PVDF) organic thin films prepared by the vapor deposition method. The differential scanning calorimetry curve of the PVDF organic thin films prepared by increasing substrate temperature showed that the melting curve increased from $128^{\circ}C$ to $142^{\circ}C$. This result implied that the PVDF organic thin film prepared by increasing substrate temperature increased intermolecular force in the crystalline region. The anomalous properties in dielectric constant and dielectric loss at low frequency and high temperature were described for PVDF organic thin film containing impurity carriers. It was confirmed that in view of electric conductive characteristics the ohm's law is satisfied in the range of lower electric field and ln J was proportional to the electric field ln E as like the conventional property of ionic conduction in the range of higher electric field. It was confirmed that major carrier of conductivity was ions. The electrical stability was improved according to an increase of the substrate temperature. On the basis of this experimental result, it could be observed that the optimum temperature of substrate for the electrical and thermal stability was at $105^{\circ}C$.

• 한국전기전자재료학회논문지
• /
• 제29권11호
• /
• pp.716-719
• /
• 2016

In this paper, we fabricated flexible CNT/PVDF (carbon nanotube / polyvinylidene fluoride) piezoelectric composite device with flexible poly(3,4-ethylenedioxythiophene) : polystyrene sulfonate (PEDOT:PSS) conducting polymer electrode using spray coating method. We tried to improve the piezoelectric performance from the CNT/PVDF composite film by enhancing electrical conductivity of the PEDOT:PSS electrodes. Electrical conductivity of the PEDOT:PSS electrode was enhanced by dipping it into the EG (ethylene glycol) solvent. Changes of chemical composition of the PEDOT:PSS electrode were analyzed with the dipping time by XPS (x-ray photoelectron spectroscopy) in terms of oxygen (O1s). Finally, Piezoelectric performances such as output voltage and current were measured with the dipping time. We found that enhanced electrical conductivity of the PEDOT:PSS electrodes resulted in improvement of the piezoelectric performance of the CNT/PVDF films.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 추계학술대회 논문집
• /
• pp.512-513
• /
• 2007

Carbon/polymer based composite electrodes were fabricated by using Super p. Black(SPB) as a conductor and polyvinylidene fluoride (PVDF) as a binder. This type of composite electrode are considered as excellent candidates for heating film and variable resistor applications. Aim of this work is the study of the Mechanical and Electrical properties on composite electrode by the contents of SPB and MWCNT, respectively. The composite electrode having 10~15 wt% of SPB show good electrical and mechanical properties. Mechanical and electrical properties are increased by the addition of MWCNT into the composite electrode.

• 한국음향학회지
• /
• 제35권3호
• /
• pp.175-182
• /
• 2016

수 MHz의 초음파를 이용하는 저주파 광음향 영상장치에 적용하는 것을 목적으로 압전단결정 PMN-PZT를 사용한 바늘형 수중청음기를 설계 제작하고, 그 특성을 수신감도가 알려져 있는 상용 PVDF(Polyvinylidene Fluoride) 수중청음기와 비교하여 평가하였다. 설계한 수중청음기의 임펄스응답을 KLM 모델에 의해 시뮬레이션한 결과, $50{\Omega}$의 종단 임피던스에 걸리는 최대 전압을 기준으로 한 수신감도는 -261.6 dB re $1V/{\mu}Pa$이며, 2 ~ 12 MHz 대역에서 5 dB 이내의 비교적 평탄한 특성을 가지는 것으로 예측되었다. 제작한 수중청음기의 수신감도를 순음 펄스를 사용하여 측정한 결과, 측정 가능한 2 ~ 8 MHz 대역에서 상용의 수중청음기에 비해 평균 10.9 dB 높게 나타났으며, 그 값은 $-255.8{\pm}2.8$ dB re $1V/{\mu}Pa$이었다. 나아가, 제작한 수중청음기를 기계주사형 광음향 영상장치에 적용하여 머리카락에 대한 영상을 획득하였는바, 수신된 광음향 신호가 상용의 것보다 크고, 영상 또한 우수함을 알았다.

• Journal of Mechanical Science and Technology
• /
• 제16권10호
• /
• pp.1222-1228
• /
• 2002

This research is the development of a flexible tactile sensor array for service robots using PVDF (polyvinylidene fluoride) film for the detection of a contact state in real time. The prototype of the tactile sensor which has 8${\times}$8 array using PVDF film was fabricated. In the fabrication procedure, the electrode patterns and the common electrode of the thin conductive tape were attached to both sides of the 281$\mu\textrm{m}$ thickness PVDF film using conductive adhesive. The sensor was covered with polyester film for insulation and attached to the rubber base for a stable structure. The proposed fabrication method is simple and easy to make the sensor. The sensor has the advantages in the implementing for practical applications because its structure is flexible and the shape of the each tactile element can be designed arbitrarily. The signals of a contact force to the tactile sensor were sensed and processed in the DSP system in which the signals are digitized and filtered. Finally, the signals were integrated for taking the force profile. The processed signals of the output of the sensor were visualized in a personal computer, and the shape and force distribution of the contact object were obtained. The reasonable performance for the detection of the contact state was verified through the sensing examples.