Дисертації з теми "Dielectric polymers"
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Akins, Robert Benjamin. "Dielectric investigation of double glass transitions in polymers." Case Western Reserve University School of Graduate Studies / OhioLINK, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=case1055878455.
Повний текст джерелаZhong, Zhengzhong. "Dielectric relaxations in side-chain liquid crystalline polymers." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1060624225.
Повний текст джерелаGupta, Sahil. "Structure-Property Relationships in Polymers for Dielectric Capacitors." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1395682393.
Повний текст джерелаGrove, Nicole R. "Characterization of functionalized polynorbornenes as interlevel dielectrics." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/11204.
Повний текст джерелаRiedel, Clément. "Dielectric and mechanical properties of polymers at macro and nanoscale." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20073.
Повний текст джерелаThe aim of this thesis was first to understand the physical theories that describe the dynamics of linear polymers at the macroscopic scale. Rouse and the reptational tube theory describe the large scale dynamics of unentangled and entangled polymers respectively. Using Broadband Dielectric Spectroscopy (BDS) and rheology we have studied the different transition between these two regimes. Effects of entanglement on dielectric spectra will be discussed (Rheologica Acta. 49(5):507-512). Avoiding the segmental relaxation contribution and introducing a distribution in the molecular weight we have been able to perform a comparison of the Rouse model with experiment dielectric and rheological data (Macromolecules 42(21): 8492-8499) Then we have developed EFM-based methods in order to study the local dynamics. Using the numerical simulation of the Equivalent Charge Method, the value of the static dielectric permittivity has been quantified from the measurement of the force gradient created by a VDC potential between a tip and a grounded dielectric (Journal of Applied Physics 106(2):024315). This method allows a quantitative mapping of dielectric properties with a 40 nm spatial resolution and is therefore suitable for the study of nano-defined domains (Physical Review E 81(1): 010801). The electrical phase lags in the 2ω components of the force or force gradient created by VAC voltage, ΔΦ2ω, are related with dielectric losses. Measuring the frequency dependence of ΔΦ2ω Crieder et al (Applied Physics Letters 91(1):013102) have shown that the dynamics at the near free surface of polymer films is faster than the one in bulk. We have used this method in order to visualize the activation of the segmental relaxation with temperature and frequency (Applied Physics Letters 96(21): 213110). All this measurements can be achieved using standard Atomic Force Microscope (and a lock-in) for VAC measurements
Nass, Kirk A. "Dielectric thermal analysis of polymeric matrices /." Thesis, Connect to this title online; UW restricted, 1989. http://hdl.handle.net/1773/9897.
Повний текст джерелаWarner, Nathaniel A. "Investigation of the Effect of Particle Size and Particle Loading on Thermal Conductivity and Dielectric Strength of Thermoset Polymers." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849629/.
Повний текст джерелаEusner, Thor. "Determining the Preston constants of low-dielectric-constant polymers." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36308.
Повний текст джерелаIncludes bibliographical references (leaf 30).
An important step in the manufacture of integrated circuits (ICs) is the Chemical Mechanical Polishing (CMP) process. In order to effectively use CMP, the removal rates of the materials used in ICs must be known. The removal rate of a given material by CMP can be determined once its Preston constant is known. The objectives of this work were to develop a method to determine the Preston constants and to measure the Preston constants of four low-dielectric-constant (low-k) polymers, labeled A, B, C, and D, and Cu. A weight-loss method, which measures the weight difference between the initial wafer and the polished wafer, provided repeatable results. The Preston constants ranged from 1.01 to 5.96 x10-'3 m2/N. The variation in measurements of the Preston constant ranged from 16% to 31%. The Preston constant of Cu was found to be 1.60 + 0.50 x10-13 m2/N. Of the four polymers, Polymer A had the smallest Preston constant, 1.01 i- 0.30 x10-13 m2/N. It was also determined that there is an approximate inverse linear relationship between the Preston constant of the four low-k polymers and their Young's moduli of elasticity. An approximate inverse linear relationship between the Preston constant of the four low-k polymers and the hardness was also observed.
by Thor Eusner.
S.B.
Xiao, Zhang. "PROBING POLYMER DYNAMICS USING HIGH THROUGHPUT BROADBAND DIELECTRIC SPECTROSCOPY." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1533127319642101.
Повний текст джерелаMaistros, G. M. "Dielectric monitoring during the cure of epoxy resin blends." Thesis, Cranfield University, 1991. http://dspace.lib.cranfield.ac.uk/handle/1826/10403.
Повний текст джерелаWalmet, Eric Robert. "In-situ monitoring of PMMA solution polymerization with dielectric microsensors." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/10036.
Повний текст джерелаDoyle, S. E. J. "The physical characteristics and dielectric behaviour of cellulose acetate polymers." Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371938.
Повний текст джерелаRomeo, Michael Joseph. "Design, synthesis, and characterization of novel, low dielectric, photodefinable polymers." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24782.
Повний текст джерелаCommittee Chair: Henderson, Cliff; Committee Member: Beckham, Haskell; Committee Member: Hess, Dennis; Committee Member: Koros, William; Committee Member: Tolbert, Laren.
Norris, Ann Marie Walstrom. "Dielectric studies of novel polymeric systems." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/53656.
Повний текст джерелаPh. D.
Wang, Jingsong Johari G. P. "Thermodynamics of polymerization, dielectric properties, and a new orientational glass /." *McMaster only, 2003.
Знайти повний текст джерелаSinno, Bilal. "Mechanical and dielectric characterization of electronic grade polymers at subambient temperatures." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/10149.
Повний текст джерелаRatnam, Mamatha D. "Correlation between the dielectric, rheological and structural properties of DGEBA-DDS epoxy." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/10203.
Повний текст джерелаSimpson, Joycelyn Ovetta. "Structure-dielectric property relationships for epoxy systems : a free volume analysis." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/10102.
Повний текст джерелаTroutman, Tia Shawana. "Development of low viscosity, high dielectric constant polymers for integral passive applications." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/8683.
Повний текст джерелаBergman, David. "The Effect of Partial Discharge Aging on the Dielectric Response of Polymers." Thesis, KTH, Elektroteknisk teori och konstruktion, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-157323.
Повний текст джерелаDet här arbetet undersökte effekten av partiella urladdningar (PD) på den komplexa permittiviteten i PVC, PC, PTFE, PE och PA6. Materialproverna utsattes för långvarig PD aktivitet och materialets komplexa permittivitet mättes med hjälp av dielektrisk spektroskopi (DS) före och efter att provet åldrats. Resultaten visade en förändring i förlustfaktorn i de testade materialen, några påverkades mer än andra och de uppvisade olika beteenden när de blev utsatta för PD åldring. Det var därför inte möjligt att hitta någon generell trend i den komplexa permittiviteten för de olika testade materialen. Flera av materialen uppvisade en förlustfaktor med -1/2 lutning vid låga frekvenser vilket motsvarar diffusion. -1/2 lutningen medför att förlustfaktorn och den dynamiska komponenten av den reella permittiviteten borde sammanfalla, vilket inte kunde ses. Det är därför osäkert huruvida det som observerats är en diffusionsprocess eller inte. Resultaten kan tyda på att PD-åldring orsakar en förändring i potentialfällors egenskaper i materialet. Således skulle rymdladdningar som deponeras på väggarna i kaviteten på grund av PD-aktiviteten kunna diffundera in i materialet där en del av laddningarna fastnar. Om en DS mätning görs innan de fångade laddningarna har fått tillräcklig tid att rekombinera eller ledas iväg, kan det påverka den komplexa permittiviteten. Detta visades genom att genomföra en DS mätning på ett åldrat prov av PC som fått vila i 35 dagar. Mätningen visade att den komplexa permittiviteten hade återgått till nästan samma tillstånd som innan den åldrades. Mätproblem påträffades vilket påverkade mätningarna i detta arbete. Problemen antas vara orsakade av att mätelektroderna som användes till DS mätningarna inte var tillräckligt tunga för att eliminera små oönskade luftgap mellan elektroderna och provet. Dessutom erhölls ofullkomliga resultat för några av mätningarna vilket tros bero på att provets kapacitans befann sig på gränsen för vad mätinstrumentet kunde mäta.
Appello, Mario. "Real-time measurement of electrical properties during the processing of conductive polymers." Thesis, University of Warwick, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341559.
Повний текст джерелаHouachtia, Afef. "Dielectric investigations on attograms and zeptograms of matter." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI006/document.
Повний текст джерелаDielectric investigations on attograms (1 attogram = 10 -18 gram) and zeptograms of matter (1 zeptogram = 10 -21 gram) offer the possibility of exploring the transition between nanoscience and molecule physics, opening the door for fundamental questions in soft-matter physics, such as for instance “What is the minimum amount of matter necessary to “define” the material properties?”. The electric and dielectric properties of materials at this level are investigated by Broadband Dielectric Spectroscopy. This technique provides an extraordinary broad frequency range, for measuring dielectric properties of matter, covering more than 10 orders of magnitude, typically from 10-3 to 10+7Hz. It ensures a precise characterization of large diversity of physical phenomena taking place at different length and time scales such as: phase transitions, density fluctuations, molecular fluctuations, charge transport processes, etc. Measurements on the scale of attograms and zeptograms require sample cells having all three dimensions on the nanometric length-scale. Based on the concept of employing nanocontainers as experimental cells, a novel experimental development allowing investigations on molecular dynamics and phase transitions of polymeric materials down to the level of zeptograms is demonstrated in the present PhD study. This approach enables one to crystallize tiny amounts of matter under high electric fields with the goal of inducing a macroscopic coherence of molecular functionalities. This could give rise to new material properties, not naturally available in the case of bulk materials
Stevens, Derrick. "Molecular Dynamics in Self-assembled Monolayers and Polymers studied via sensitive Dielectric Spectroscopy." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-07052009-111325/.
Повний текст джерелаHegde, Vikas. "Etudes diélectriques des matériaux biodégradables et/ou bio-sourcés." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT031/document.
Повний текст джерелаThe declining resources of fossil fuels, increase in wide-spread pollution, emission of green-house gases and difficulties in recycling waste materials are pushing biodegradable polymers into prominence. In the domain of electrical engineering, many polymers find applications in various electrical insulation systems. These polymers are petro-based, not eco-friendly and most of them are not biodegradable. With an objective to replace conventional products, biodegradable polymers are explored for their dielectric properties.In this work, a detailed study on the present status in the research work on biodegradable polymers in the electrical engineering domain is presented. Thermal and electrical properties of both biodegradable and classical polymers are compiled and compared.The polymers processed and studied were Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), Polycaprolactone (PCL), Poly(lactic acid) (PLA) and PLA based nanocomposite. Dielectric properties for a wide range of temperature and frequency were measured by dielectric spectroscopy and analyzed with the help of DSC and DMA experiments. Volume resistivity and electrical breakdown were measured on few polymers. These biodegradable polyesters were compared with conventional polymers
Kunal, Kumar. "Influence of Chemical Structure and Molecular Weight on Fragility in Polymers." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1247855648.
Повний текст джерелаChen, Xinyue. "Understanding Loss Mechanisms and Enhancing Dielectric Properties of Multilayer Polymer Films for Capacitor Applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1584527483998243.
Повний текст джерелаWang, Chunlai. "AZADIPYRROMETHENE-BASED N-TYPE ORGANIC SEMICONDUCTORS AND HIGH DIELECTRIC CONSTANT POLYMERS FOR ELECTRONIC APPLICATIONS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case156708229609051.
Повний текст джерелаKanbur, Yasin. "Conductive Polymer Nanocomposites Of Polypropylene And Organic Field Effect Transistors With Polyethylene Gate Dielectric." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613312/index.pdf.
Повний текст джерелаs and fullerenes were surface functionalized with HNO3 : H2SO4 before composite preparation. The CNT and fullerene content in the composites were varied as 0.5, 1.0, 2.0 and 3.0 % by weight. For the composites which contain surface modified CNT and fullerene four different compatibilizers were used. These were selected as TritonX-100, Poly(ethylene-block-polyethylene glycol), Maleic anhydride grafted Polypropylene and Cetramium Bromide. The effect of surface functionalization and different compatibilizer on mechanical, thermal and electrical properties were investigated. Best value of these properties were observed for the composites which were prepared with maleic anhydride grafted polypropylene and cetramium bromide. Another aim of this study is to built and characterize transistors which have polyethylene as dielectric layers. While doing this, polyethylene layer was deposited on gate electrode using vacuum evaporation system. Fullerene , Pentacene ve Indigo were used as semiconductor layer. Transistors work with low voltage and high on/off ratio were built with Aluminum oxide - PE and PE dielectrics.
Pušec, Daniel. "Účinky vlhkosti na elektrické vlastnosti silikonového kaučuku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242853.
Повний текст джерелаRao, Yang. "High dielectric constant materials development and electrical simulation of embedded capacitors." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/20014.
Повний текст джерелаKerr, Maria. "The grafting of collagen to medically relevant polymers through an atmospheric pressure dielectric barrier discharge." Thesis, University of Ulster, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536466.
Повний текст джерелаAndersen, Allen. "The Role of Recoverable and Non-Recoverable Defects in DC Electrical Aging of Highly Disordered Insulating Materials." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7047.
Повний текст джерелаMackey, Matthew. "Enhanced Dielectric Properties of Micro and Nanolayered Films for Capacitor Applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1333479475.
Повний текст джерелаRajarathinam, Venmathy. "Imprint lithography and characterization of photosensitive polymers for advanced microelectronics packaging." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34722.
Повний текст джерелаLiu, Tao. "Determination of three dimensional refractive indices and absorption coefficients of anisotropic polymer films with prism wave-guide coupler." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/8601.
Повний текст джерелаSu, Ruo Qing. "New composite material based on silsesquioxane polymers and nanoporous particles for low-k [low-kappa] dielectric application." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972240519.
Повний текст джерелаARAMBULO, PABLO CESAR SERRANO. "INVESTIGATION OF DIELECTRIC LAYER FOR THE DEVELOPMENT OF ORGANIC FIELD EFFECT TRANSISTORS (OFET) BASED ON CONJUGATED POLYMERS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33715@1.
Повний текст джерелаCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Nos últimos anos, polímeros conjugados ganharam muita atenção na eletrônica orgânica por seu uso na fabricação de dispositivos flexíveis e de baixo custo. Como resultado, diferentes tipos de dispositivos têm sido desenvolvidos como: diodos emissores de luz orgânicos (OLEDs), células fotovoltaicas orgânicas (OPVs) e transistores de efeito de campo orgânicos (OFETs). Em particular, para os OFETs seu desempenho depende da interface isolante/semicondutor, principalmente, devido ao acúmulo de portadores de carga. Além disso, as propriedades da interface afetam fortemente o transporte de carga através do canal de dispositivo. Por estas razões, a pesquisa de novos polímeros semicondutores e novos materiais dielétricos é um fator chave para aprimorar o desempenho dos dispositivos. Neste trabalho, os polímeros PMMA, PVA, FORMVAR e PU foram investigados como materiais dielétricos. Inicialmente foram fabricados capacitores de placas planas paralelas do tipo ITO/dielétrico/Al para determinar a constante dielétrica dos isolantes, as curvas JxV e a capacidade por unidade de área. Desenvolveu-se OFETs tipo Top-Gate/Bottom-Contacts (TGBC) com a estrutura Au/P3HT/PMMA/Ag e Au/P3HT/PU/Ag. No trabalho, a espessura dos dielétricos foi variada para aprimorar o desempenho dos dispositivos. Para os OFETs de PMMA obteve-se resultados concordantes com os da literatura. Os novos OFETs de PU apresentaram tensões de operação menores que 5V, que é um requisito para a integração destes OFETs em aplicações da eletrônica orgânica. A mobilidade obtida nestes OFETs de PU foi de 1.25 cm(2)/V.s, com uma tensão limiar de 0.02 e uma razão On/Off de 100.
In the last years, conjugated polymers have received much attention in organic electronics for their use in the fabrication of low cost and flexible devices. As a result, different types of devices have been developed e.g. organic light emitting diodes (OLEDs), photovoltaic devices (OPVs) and field effect transistors (OFETs). For the OFETs in particular, their performance depends primarily on insulator/semiconductor interface, mainly due to charge carrier accumulation. Moreover, the interface properties strongly affect the charge transport through the device channel. For these reasons, the research for new semiconductor polymers and new dielectric materials is key to advancing the performance improvement of devices. In this work, the polymers PMMA, PVA, FORMVAR and PU were used as dielectric materials. Initially, parallel plate capacitors of the structure ITO/dielectric/A1 were made, in order to determine the dielectric constant of the insulators, get the curves JxV and the capacity per unit area. It was used to develop Top-Gate/Bottom-Contacts (TGBC) OFETs with structures of Au/P3HT/PMMA/Ag and Au/P3HT/PU/Ag. The thicknesses of the dielectric materials were varied to improve the performance of the devices. For the PMMA OFETs, the results obtained were concordant with those of the existing literature. The new PU OFETs presented with operating voltages of less than 5V, appropriate for applications of these OFETs in organic electronics. The mobility of the PU OFETs was 1.25cm(2)/V.s, the threshold voltage 0.02V and the On/Off ratio 100.
Pejic, Sandra. "Structure-Property Studies of Substituted Azadipyrromethene-Based Dyes and High Dielectric Constant Polymers for Organic Electronic Applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1527949734211196.
Повний текст джерелаMohomed, Kadine. "Thermal analyses of hydrophilic polymers used in nanocomposites and biocompatible coatings." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001442.
Повний текст джерелаCabral, Flávio Pandur Albuquerque. "Medidas das constantes dielétricas e deslocamento elétrico em dielétricos: desenvolvimento da técnica e metodologia." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-08042014-151001/.
Повний текст джерелаA low cost and a simple experimental system for measuring the complex dielectric constant of dielectric samples were developed. Measurements were performed measuring the electric charge response resulting from the application of a sinusoidal voltage. The system was based on an A/D acquisition board with sampling rate of 100 Ksamples/sec. The complex impedance was calculated using the discrete Fourier transform from which the complex dielectric constant was found. The phase differences introduced by the A/D board and the amplifiers circuits were connected by software. The setup showed that the results are comparable to that ones obtained with commercial impedance analyzers in the range of frequencies between 0.1 Hz and 1 KHz. Such measurements were obtained using resistors and/or capacitors and also using samples of Teflon FEP, PVDF and its copolymers with trifluorethylene. The setup was also capable to measure the electric displacement in ferroelectric polymers submitted to high fields. Hysteresis loops and the nonlinear electric displacement of first, second and third order were measured.
Tseng, Jung-Kai. "Enhanced Dielectric Properties of Multilayer Capacitor Film via Interfacial Polarization." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1449137228.
Повний текст джерелаSpencer, Todd Joseph. "Air-gap transmission lines on printed circuit boards for chip-to-chip interconnections." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34754.
Повний текст джерелаHalethimmanahally, Thejaswini C. [Verfasser]. "Atmospheric-Pressure Dielectric Barrier Discharges: Synthesis and Deposition of Organic plasma polymers and their characterizations / Thejaswini C. Halethimmanahally." Greifswald : Universitätsbibliothek Greifswald, 2012. http://d-nb.info/1028455658/34.
Повний текст джерелаMurray, Christopher Ian. "The study of side chain organisation in liquid crystalline polymers using dielectric relaxation spectroscopy and X-ray diffraction." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286908.
Повний текст джерелаSantos, Alessandro Luiz Ribeiro dos [UNESP]. "Estudo de polímeros comerciais tratados a plasma em pressão atmosférica." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/91830.
Повний текст джерелаFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Materiais poliméricos têm sido amplamente utilizados em várias áreas tecnológicas e biomédicas, devido às suas excelentes propriedades mecânicas, térmicas e elétricas. No entanto, estes materiais têm baixa energia de superfície e, portanto, não aderem facilmente a outros materiais. Por isso, para muitas aplicações é necessário modificar a superfície do polímero, a fim de aumentar a sua energia de superfície. Tratamentos a plasma à pressão atmosférica têm sido muito utilizados para modificar as propriedades superficiais de polímeros comerciais, devido aos baixos custos do processo. Este trabalho apresenta os resultados do tratamento de tereftalato de polietileno (PET), poliuretano (PU) e de politetrafluoretileno (PTFE) em plasma de descargas com barreira dielétrica (DBD) em ar, nitrogênio e argônio, à pressão atmosférica. As superfícies tratadas foram caracterizadas por medidas de ângulo de contato, espectroscopia de fotoelétrons de raios-X (XPS) e microscopia de força atômica (AFM). A superfície polimérica, modificada nas DBD a pressão atmosférica, mostraram uma redução significativa no ângulo de contato da água, embora uma recuperação parcial da molhabilidade ocorresse nos primeiros dias após o tratamento. Todavia, a recuperação foi insuficiente para que as amostras tratadas recuperassem a sua molhabilidade original. Análises de XPS mostraram um aumento na concentração de oxigênio na superfície, devido à formação de grupos polares, tais como C-O e OC= O. Um pequeno aumento na concentração de nitrogênio também foi observada. Imagens de AFM mostraram um aumento da rugosidade de polímeros tratados, decorrentes da interação física entre as espécies geradas na descarga e a superfície do polímero. A superfície ativada e a elevada tensão superficial dos polímeros tratados devem levar a um aumento da aderência do polímero.
Polymeric materials have been widely used in various biomedical and technological applications, due to their excellent mechanical, thermal and electric properties. However, these materials have low surface energy, and thus not easily adhere to other materials. Therefore, for many applications it is necessary to modify the polymer surface in order to increase its surface energy. Plasma treatments at atmospheric pressure have been frequently used to modify the surface properties of commercial polymers, due to their low process costs. This work reports the results of polyethylene terephthalate (PET), polyurethane (PU) and polytetrafluoroethylene (PTFE) treatments in plasma by dielectric barrier discharges (DBDs) in air, nitrogen and argon at atmospheric pressure. The plasma-modified surfaces were characterized by contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The polymer surface, modified by DBD at atmospheric pressure, showed a significant decrease in water contact angle although a partial recovery of the surface wettability occurred during the first few days after the treatment. However, the process of hydrophobic recovery was insufficient for complete recovering of the samples original wettability. XPS analysis showed an increase of the oxygen concentration on the surface, due to the formation of polar groups, such as C-O and OC= O. A small increase in the concentration of nitrogen was also observed. AFM images exhibit an increased roughness of the treated polymers because of the physical interaction between the species generated in the discharge and the polymer surface. The activated surface and high surface tension of treated polymers should promote an enhancement of the polymer adhesion to paints and coatings.
Fiocco, Laura. "Silicate ceramics from preceramic polymers and fillers." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424243.
Повний текст джерелаL’attività di ricerca presentata in questa tesi ha riguardato la sintesi, la caratterizzazione e l’ottimizzazione di ceramici silicatici, realizzati a partire dalla pirolisi controllata di polimeri preceramici caricati con fillers inorganici. Sulla base di tale metodo di sintesi, i polimeri preceramici possono essere utilizzati come precursori per l’ottenimento di silice in virtù della loro conversione da polimeri a ceramici tramite reazioni termo-ossidative. Oltre al basso costo, alla larga disponibilità e alla semplicità di utilizzo, un ulteriore vantaggio riguarda la fabbricazione del ceramico finale dal punto di vista del processo. Infatti, il componente può essere formato sfruttando le convenzionali tecniche di formatura per i materiali polimerici, sfruttando la presenza di una componente polimerica nel sistema prima di imporne la reticolazione. Tali semplici tecniche di formatura includono anche la realizzazione di componenti densi, tramite pressatura, o di corpi altamente porosi, tramite stampaggio 3-D diretto o schiumaggio delle miscele preceramiche, prima di ceramizzarle. L’inserimento di fillers, che generalmente si suddividono in attivi e passivi, è considerata una delle più efficaci strategie per ridurre il ritiro dimensionale e la formazione di macrodifetti, che inevitabilmente hanno luogo durante la conversione da materiale polimerico a ceramico, permettendo la realizzazione di componenti relativamente spessi. Un approccio più innovativo relativo all’uso di fillers reattivi, invece, riguarda l’introduzione di fillers come precursori di ossidi che possano reagire completamente con il residuo ceramico dei precursori polimerici, piuttosto che finalizzati a compensare il ritiro dimensionale dei componenti. Dalle reazioni tra i precursori polimerici e i fillers reattivi durante la pirolisi, risulta la formazione di fasi cristalline specifiche, che generalmente non sono ottenibili in modo diretto dal semplice trattamento termico dei precursori polimerici. Seguendo tale processo di sintesi, la presente tesi di dottorato ha avuto come obiettivo lo studio delle applicazioni che tale tecnica potrebbe offrire, partendo da miscele a base di polimeri siliconici caricati con filler reattivi. In questo modo, i vantaggi derivanti dalla presenza di una componente polimerica, sfruttati soprattutto in fase di formatura, possono anche essere combinati con i vantaggi offerti dall’intero ciclo produttivo di ceramici da polimeri preceramici, portando alla realizzazione di componenti ceramici a temperature abbastanza basse (entro i 1200 °C) e evitando i metodi di sintesi più convenzionali. Nel presento lavoro di ricerca, i fillers incorporati nelle miscele preceramiche sono anche stati sfruttati come agenti schiumanti o formatori di fase liquida, permettendo rispettivamente lo schiumaggio diretto di componenti altamente porosi in un caso e l’ottenimento di vetro-ceramiche nel secondo. Ad ogni modo, come già spiegato, il fine principale dell’uso dei fillers, qui, è stato il loro utilizzo come precursori di ossidi, in modo da permettere, dopo ceramizzazione, la sintesi di fasi ceramiche cristalline di specifica composizione, direttamente ottenibili dalla reazione tra il residuo ceramico dei precursori polimerici e gli ossidi provenienti dalla decomposizione termica dei fillers reattivi. La tipologia di fillers può essere adeguatamente modificata a seconda della composizione finale desiderata; di conseguenza, un’enorme varietà di sistemai ceramici può essere realizzata semplicemente modificando le proporzioni e la composizione dei polimeri e dei fillers di partenza. La prima parte dei capitoli seguenti sarà imperniata sulla realizzazione di particolari ceramici e vetro-ceramiche molto conosciuti per le loro pronunciate proprietà biologiche, oltre che sulla loro formatura in strutture adeguate in applicazioni biomedicali come impianti per rigenerazione ossea. Infatti, parallelamente ai biovetri, altre formulazioni bioceramiche hanno ricevuto recentemente un interesse crescente nel campo biomedicale, in virtù della loro capacità di stimolare i tessuti biologici ad auto-ripararsi. Le formulazioni qui sviluppate appartengono prevalentemente ai sistemi di ossidi del tipo CaO-SiO2 o CaO-MgO-SiO2, ma alcune fasi cristalline sono anche state combinate tra loro per ottenere formulazioni composite, oppure sono state rivestite con altri materiali, come l’idrossiapatite, esibenti proprietà simili a quelle dell’osso naturale sotto il punto di vista sia chimico che strutturale, al fine di incrementarne ulteriormente la bioattività. In questo contesto, i materiali sviluppati sono stati caratterizzati non solo dal punto di vista microstrutturale, meccanico e fisico, ma è stato studiato anche il loro comportamento sotto il profilo biologico. Inoltre, sfruttando il concetto di multifunzionalità che caratterizza alcuni silicati, oltre alle profonde analogie in termini di struttura cristallina e di caratteristiche di processo, è stato possibile stabilire un filo conduttore tra i biosilicati sopra menzionati e altri silicati con altre applicazioni funzionali avanzate. In quest’ottica, la tecnologia è stata estesa ad altri silicati caratterizzati da proprietà dielettriche, luminescenti e refrattarie.
Carr, Joel Matthew. "CONFINED LAYERED POLYMERIC SYSTEMS FOR PACKAGING ANDCAPACITOR APPLICATIONS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1363104386.
Повний текст джерелаSantos, Alessandro Luiz Ribeiro dos. "Estudo de polímeros comerciais tratados a plasma em pressão atmosférica /." Guaratinguetá : [s.n.], 2010. http://hdl.handle.net/11449/91830.
Повний текст джерелаAbstract: Polymeric materials have been widely used in various biomedical and technological applications, due to their excellent mechanical, thermal and electric properties. However, these materials have low surface energy, and thus not easily adhere to other materials. Therefore, for many applications it is necessary to modify the polymer surface in order to increase its surface energy. Plasma treatments at atmospheric pressure have been frequently used to modify the surface properties of commercial polymers, due to their low process costs. This work reports the results of polyethylene terephthalate (PET), polyurethane (PU) and polytetrafluoroethylene (PTFE) treatments in plasma by dielectric barrier discharges (DBDs) in air, nitrogen and argon at atmospheric pressure. The plasma-modified surfaces were characterized by contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The polymer surface, modified by DBD at atmospheric pressure, showed a significant decrease in water contact angle although a partial recovery of the surface wettability occurred during the first few days after the treatment. However, the process of hydrophobic recovery was insufficient for complete recovering of the samples original wettability. XPS analysis showed an increase of the oxygen concentration on the surface, due to the formation of polar groups, such as C-O and OC= O. A small increase in the concentration of nitrogen was also observed. AFM images exhibit an increased roughness of the treated polymers because of the physical interaction between the species generated in the discharge and the polymer surface. The activated surface and high surface tension of treated polymers should promote an enhancement of the polymer adhesion to paints and coatings.
Orientador: Konstantin Georgiev Kostov
Coorientador: Roberto Yzumi Honda
Banca: Konstantin Georgiev Kostov
Banca: Rogério Pinto Mota
Banca: Gilberto Petraconi Filho
Mestre
Eder-Goy, Dagmar [Verfasser], Baixiang [Akademischer Betreuer] Xu, and Dietmar [Akademischer Betreuer] Gross. "Numerical Studies on the Influence of Dissipative Effects on Electromechanical Properties of Dielectric Polymers / Dagmar Eder-Goy ; Baixiang Xu, Dietmar Gross." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1199006602/34.
Повний текст джерелаEder-Goy, Dagmar [Verfasser], Bai-Xiang [Akademischer Betreuer] Xu, and Dietmar [Akademischer Betreuer] Gross. "Numerical Studies on the Influence of Dissipative Effects on Electromechanical Properties of Dielectric Polymers / Dagmar Eder-Goy ; Baixiang Xu, Dietmar Gross." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1199006602/34.
Повний текст джерела