Ces travaux de thèse contribuent à l’étude de matériaux hybrides à base d’un polymère semi cristallin, le polyfluorure de vinylidène (PVDF) connu pour ses propriétés piézoélectriques. Cependant, celles-ci dépendent du polymorphisme du PVDF et les phases polaires nécessaires à l’obtention de telles propriétés sont classiquement obtenues par étirage ou par incorporation de charges. L’objectif de ces travaux est la compréhension des comportements mis en jeu au cours d’essais d’étirage et l'évaluation de l’influence des charges sur les propriétés résultantes. L’originalité de ces travaux réside dans le suivi in-situ de l’évolution structurale durant l’étirage, permettant de conclure que la phase polaire β du PVDF se forme lors de la striction et que la relaxation cristalline joue un rôle primordial sur les mécanismes de déformation du PVDF. L’insertion de nanotubes de carbone (NTC) dans la matrice PVDF induit un changement partiel de phase cristalline apolaire α-->polaire γ. Le taux de cette phase induite passe par un maximum pour un taux de NTC proche du seuil de percolation. L’étude in-situ sous étirage de ces composites montre que la présence de NTC n’affecte pas la formation de la phase polaire β du PVDF induite mécaniquement. Pour améliorer les propriétés piézoélectriques du PVDF, des composites à base de céramiques piézoélectriques (BaTiO3) ont été élaborés. Cependant l’interface entre les deux constituants est peu cohésive. L’utilisation d’un dérivé de dopamine, la nitro-dopamine permet d’améliorer l’adhésion interfaciale mais n’engendre pas de changement de phase cristalline du PVDF. L’étude piézoélectrique des composites étirés souligne le potentiel de tels systèmes. / This work is a contribution to the study of hybrid materials based on a semi-crystalline polymer: poly(vinylidene fluoride), PVDF, well known for its piezoelectric properties. However these properties are dependent of the PVDF crystalline structure which must be in polar form. The most polar phase (β) is classically obtained by stretching the non-polar phase (α) or by incorporating fillers.The aim of this work is the understanding of structural changes and deformation mechanisms of PVDF during stretching. The impact of the incorporation of different (nano)fillers on PVDF structure and mechanical behavior is also studied.The distinctive feature of this work is the use of synchrotron radiation for in-situ strain-induced structural evolution studies. These experiments show that the polar β phase appears with necking and that the crystalline relaxation of PVDF plays a main role on plasticity mechanisms.The incorporation of carbon nanotubes (CNT) in PVDF matrix leads to a partial crystalline change from non-polar form α to a polar form γ. The ratio of this γ phase is maximal for a CNT loading close to the electric percolation threshold. The in-situ structural evolution shows that CNT's do not affect the formation of the mechanically-induced polar β phase.In order to improve the PVDF piezoelectric properties, composites based on piezoelectric ceramics (BaTiO3) are elaborated. Nevertheless, interactions between PVDF and BaTiO3 are too weak. The use of a dopamine derivative, nitro-dopamine improves the interfacial interactions but does not change the PVDF crystalline form. However a piezoelectric study of these stretched composites suggests interesting electroactive capabilities.

O objetivo deste trabalho foi o de preparar filmes de PVDF na fase ? , caracterizá-lo morfologicamente e polarizá-lo eletricamente para induzir a atividade piezoelétrica. Foram feitos estudos do processo de polarização elétrica em função do tempo, da temperatura e do campo elétrico aplicado na amostra. Também estudou-se a estabilidade da atividade piezoelétrica induzida. Os resultados experimentais são discutidos usando-se o modelo de Broadhurst o qual descreve as mudanças morfológicas e as propriedades elétricas do material. Apresenta-se também uma discussão das possíveis aplicações dos filmes de PVDF- ? e, em particular, a descrição de um microfone e sua caracterização eletro-acústica. / This work is aimed to describe the preparation of piezoelectric ? -PVDF films, its morphological characterization, and its piezoelectric activity induced by electric field. Polarization measurements were carried out as a function of time, temperature and the applied electric field. The piezoelectric activity decay was also studied. Using the model proposed by Brodhurst we discuss the material structure modifications and the electric properties. A general discussion on engineering applications of ? -PVDF is presented and specially a ? -PVDF microphone and its electric-acustics characterization is showed.

O objetivo deste trabalho foi o de preparar filmes de PVDF na fase ? , caracterizá-lo morfologicamente e polarizá-lo eletricamente para induzir a atividade piezoelétrica. Foram feitos estudos do processo de polarização elétrica em função do tempo, da temperatura e do campo elétrico aplicado na amostra. Também estudou-se a estabilidade da atividade piezoelétrica induzida. Os resultados experimentais são discutidos usando-se o modelo de Broadhurst o qual descreve as mudanças morfológicas e as propriedades elétricas do material. Apresenta-se também uma discussão das possíveis aplicações dos filmes de PVDF- ? e, em particular, a descrição de um microfone e sua caracterização eletro-acústica. / This work is aimed to describe the preparation of piezoelectric ? -PVDF films, its morphological characterization, and its piezoelectric activity induced by electric field. Polarization measurements were carried out as a function of time, temperature and the applied electric field. The piezoelectric activity decay was also studied. Using the model proposed by Brodhurst we discuss the material structure modifications and the electric properties. A general discussion on engineering applications of ? -PVDF is presented and specially a ? -PVDF microphone and its electric-acustics characterization is showed.

Le Poly(vinylidene-fluoride) (PVDF) est un polymère piézoelectrique pouvant être utilisé comme capteur, actuateur ou pour de la récupération d'énergie. Son copolymère dérivé le poly(vinylidene-fluoride–trifluoroethylene) (P(VDF-TrFE)) possède des propriétés similaires tout en étant plus simple à préparer que le PVDF. Il est compatible avec une technologie tout imprimée pour fabriquer des dispositifs transparents sur des substrats flexibles. Le premier objectif de cette thèse est d'analyser l’intérêt des couches minces de P(VDF-TrFE) imprimées pour l'actuation et de comparer avec la dernière génération de polymères dérivés: le Poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)). Après une étude des différentes compositions l'objectif est d'améliorer la compréhension des mécanismes de déformations pour ouvrir la voie à de nouvelles améliorations. Les travaux menés sont présentés ici en trois parties distinctes. La première est consacrée à l’étude des propriétés mécaniques et électriques des polymères. L'influence du taux de CTFE est analysée et les polymères séparés en 3 catégories distinctes en fonction de leur nature ferroélectrique. Les performances pour l'actuation de chacune de ces catégories sont étudiées. Deux figures de merites sont retenues : le déplacement (et la force) que peuvent générer l'actuateur et le coefficient de couplage pour comparer le coût en énergie du dispositif. Le choix d'un terpolymère adapté dépend de l'application envisagée et peut permettre une augmentation significative de la réponse mécanique comparé à un copolymère. En revanche le coût énergétique est toujours beaucoup plus important, au minimum le double, quelle que soit l'application .Cette première étude a aussi mis en évidence l'hystérésis et les non-linéarités dans la relation champ électrique-déformation des polymères. La deuxième partie reprend les relations constitutives de la piézoélectricité pour analyser plus avant les divergences entre la théorie et l'expérience. Ces divergences servent de points de départ à des hypothèses et modèles de déformation dans le copolymères et dans les terpolymères. De nombreuses observations indirectes montrent l'existence d'une transition de phase sous l'effet du champ électrique; en se basant sur les données de déformation et de polarisation, l'analyse présentée ici identifie une plage limitée de champ pour cette transition et quantifie son poids dans la déformation totale du matériau.La troisème partie est consacrée à la mise en évidence expérimentale des hypothèses de la partie précédente. La principale étude est l'observation in-situ de la transition de phase sous l'effet du champ par diffraction aux rayons X. Cette mise en évidence expérimentale confirme une partie des explications avancées et une étude en température permet d'aller plus loin en jouant sur la dépendance des phases à la température.Ces travaux apportent une analyse de la viabilité des différents polymères pour l'actuation. L'étude de la relation champ électrique-déformation apporte des outils pour la modélisation et une meilleure compréhension des mécanismes à l’œuvre dans ces matériaux. Les observations in-situ de la microstructure permettent de valider physiquement les modèles présentés. Ils apportent une meilleure compréhension de la physique même si de nombreuses zones d'ombre subsistent, notamment au niveau de la phase amorphe. / Poly (vinylidene-fluoride) (PVDF) is a piezoelectric polymer that can be used as a sensor, actuator or for energy harvesting. Its copolymer derivative poly (vinylidene-fluoride-trifluoroethylene) (P (VDF-TrFE)) has similar properties whilst being easier to process than PVDF. It is compatible with fully printed technologies to make transparent devices on flexible substrates. The first objective of this thesis is to analyze the interest of print thin films of P (VDF-TrFE) for the actuation and to compare with the last generation of derived polymers: Poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) ( P (VDF-TrFE-CTFE)) terpolymers. After a study on the different compositions the objective is to improve the understanding of the deformation mechanisms to pave the way for new improvements. The work is presented here in three separate parts. The first is devoted to the study of the mechanical and electrical properties of polymers. The influence of the CTFE content is analyzed and the polymers separated into 3 distinct categories based on their ferroelectric nature. The performances for the actuation of each of these categories are studied. Two figures of merits are retained: the displacement (and the force) that can be generated by the actuator and the coupling coefficient to compare the energy cost of the device. The choice of a suitable terpolymer depends on the intended application and may allow a significant increase in the mechanical response compared to a copolymer. On the other hand the energy cost with a terpolymer is always much more important, at least twice that of a copolymer.This first study revealed hysteresis and nonlinearities in the electric field-strain relationship of polymers. The second part takes up the constituent relations of piezoelectricity to analyze further the divergences between the theory and the experiment. These divergences serve as starting points to understand and model the deformation in co- and ter-polymers. Many indirect observations show the existence of a phase transition under the effect of the electric field; based on deformation and polarization data, the analysis presented here identifies a limited field range for this transition and quantifies its weight in the total deformation of the material.The third part is devoted to the experimental demonstration of the hypotheses made in the modelling section. The main study is the XRD in-situ observation of the phase transition under the effect of an electrical field. This experimental evidence confirms some of the proposed explanation and a temperature study allows us to go further, making use of the dependence of phases stability to the temperature.This work provides an analysis of the viability of the various polymers for the actuation. The study of the electric field-strain relationship provides tools for modeling and a better understanding of the mechanisms at work in these materials. In-situ observations of the microstructure make it possible to physically validate the models presented. They bring a better understanding of physics even if many uncertainties remain, especially in the amorphous phase.

Polyvinylidene Fluoride (PVDF) is a common piezoelectric polymer. It is widely utilized because of its advantageous mechanical, chemical, and electromechanical properties. An interesting application for its properties lies in using it as an actuator, specifically for a microgripper device. The microgripper has many applications such as surgeries, microassembly, and micromanipulation. The friction force is an important criterion that greatly affects the gripping. This research studies the frictional behavior of the PVDF and effects of applied electrical potential. Approaches include tribological investigation of the polymer associated with surface properties. The surface characterization was conducted using a profilometer and an Atomic Force Microscope (AFM). In addition, the application of a PVDF material as a microgripper is addressed along with the design of the gripper. It was found that the friction could be turned-on and off because of external applied electrical potential. Such behavior was associated with the microstructure, where dipoles were aligned in an electrical field. Such active-friction has not been reported in the past. This work opens new areas of research in fundamental friction that benefits the design and development of small devices such as a microgripper.

Medidas de corrente termoestimuladas e de carga a temperatura constante, sob campo elétrico constante externo, foram realizadas no intuito de identificar além de cargas espaciais existentes em amostras comerciais de PVDF, também estudar o pico anômolo de corrente que se apresentou nas medidas isotérmicas. Este pico desaparecia em medidas subseqüentes, mas sua recuperação, apesar de lenta, foi registrada, principalmente se a amostra era conservada em ambiente úmido. Uma série de medidas feitas em diferentes umidades relativas do ar, cuidadosamente controladas, evidenciou que este fenômeno estava diretamente ligado à água absorvida pela amostra do ambiente externo. O efeito mostrou também ser fortemente dependente do campo aplicado. Um modelo baseado em dissociação iônica da água, provavelmente fracamente ligada a estrutura do polímero, foi desenvolvido, levando em consideração que o coeficiente de dissociação depende do campo elétrico, bem como do tempo de extração dos portadores dissociados da amostra. Nesta cinética controladora da corrente, é considerada também recombinação bi-iônica. / Thermally stimulated current and depolarization measurements were carried on commercially available samples of PVDF. The measurements were conducted under constant temperature and constant applied field in order to investigate an anomolous peak which appears in isothermal measurements, and also identify the presence of space charge. This peak is observed only in the first measurements, but it can recover if the sample is stored in a humid environment. Series of measurements was carried out with carefully controlled relative humidity from which one can conclude that the peak is directly linked to water absorved by the sample. This effect is shown to depend strongly on the applied electric field. A theoretical model based on ionic dissociation of water molecules - probably weakly attached to the polymer structure is developed to explain the experimental results. In the model, the dissociation coefficient and the time of escape of dissociated carriers are assumed to depend on the electric field. Bi-ionic recombination is also assumed to play an important role in the control of the kinetics of the process.

O poli(fluoreto de vinilideno) (PVDF) é um polímero semicristalino que quando cristalizado a partir da fusão à temperaturas acima de 155°C apresenta uma variada morfologia cristalina, constituída por esferulitos anelados, não anelados e mistos. Abaixo dessa temperatura somente os esferulitos anelados são formados. Neste trabalho foi realizado um estudo morfológico do PVDF, procurando verificar a relação entre o tipo de esferulito formado e a fase cristalina predominante em suas lamelas. Foi verificado, por espectroscopia no infravermelho, que os esferulitos anelados apresentam exclusivamente a fase alfa, quando a cristalização ocorre a temperaturas inferiores a 155°C. Temperaturas superiores a essa induzem nessas estruturas uma transformação de fase alfa em gama, que aumenta a quantidade de fase gama com o tempo de cristalização. A taxa com que essa transformação ocorre aumenta com a temperatura de cristalização. Os esferulitos não anelados são constituídos predominantemente pela fase gama, cristalizada diretamente do fundido, com pequenas inclusões de fase alfa. O processo de fusão dos diferentes esferulitos, observado por microscopia ótica (MOLP) e medidas calorimétricas (DSC), mostraram que a temperatura de fusão da fase gama originada da transformação de fase é 8°C superior à daquela cristalizada diretamente do fundido. Micrografias de amostras aquecidas até 186°C e rapidamente resfriadas permitiram visualizar as regiões dos esferulitos anelados que sofreram a transformação de fase alfa em gama, para diferentes tempos e temperaturas de cristalização. Foi realizado, ainda, um estudo morfológico de blendas PVDF/P(VDF-TrFE), com diferentes composições e com o copolímero contendo 72% em mol de VDF. Análises térmicas (DSC) verificaram que os componentes da blenda são imiscíveis na fase cristalina, quando a cristalização ocorre a partir da fusão. Porém, micrografias obtidas por MOLP e MEV indicaram a presença de moléculas do copolímero nas regiões interlamelares dos esferulitos formados durante a cristalização do PVDF. Esse resultado sugere a miscibilidade entre os componentes no estado líquido, e que esta mistura íntima deve permanecer durante a cristalização, resultando na miscibilidade dos componentes na fase amorfa. / Poly(vinylidene fluoride) (PVDF) is a semi crystalline polymer that, when is crystallized from the melt at temperatures above 155°C, it presents a multiform morphology composed of ringed, non-ringed and mixed spherulites. Above this temperature only ringed spherulites are formed. In this work a morphological study of PVDF was performed, endeavoring to investigate the relation between the type of spherulite formed and the dominant crystalline phase in their lamellas. Infrared spectroscopy showed that the ringed spherulites are formed exclusively by the alpha phase when crystallization takes place at temperatures below 155°C. Higher temperatures induce a solid-state alpha in gamma phase transformation in these structures, increasing the amount of gamma phase with crystallization time. The rate at which this transformation takes place increases with crystallization temperature. The non-ringed spherulites consist predominantly of the gamma phase, crystallized from the melt, with small alpha phase inclusions. The melt process of the different spherulites, observed by optical microscopy (MOLP) and calorimetric measurements (DSC) showed that the melt temperature of the gamma phase originated from the phase transition is 8°C higher than that crystallized directly from the melt. Micrographs of samples heated up to 186°C and quickly cooled allowed visualization of the ringed spherulite regions, which underwent the alpha in gamma phase transformation at different crystallization times and temperatures. In addition, it was observed a morphological study of blends, with different compositions and the copolymer containing 72 mol% of VDF. Thermal analysis (DSC) showed that blend components are immiscible on crystalline phase, when the crystallization from the melt occurs. However, micrographs obtained from MOLP and MEV indicated the presence of copolymer on spherulites interlamellar regions, formed during PVDF crystallization. This result suggests miscibility between the components in the liquid state, and this intimate mixture must remain during crystallization, resulting in miscibility of the components in amorphous phase.

Nesta dissertação relatamos os resultados de medidas elétricas realizadas, a maioria delas, em folhas de 25&#956m de polivinilidene de flúor (PVDF), e em menor número em folhas de tetrafluoretileno-hexafluorpropileno (Teflon FEP). Correntes de polarização sob variadas tensões e de despolarização foram medidas a várias temperaturas e com temperatura variável. O PVDF sofre modificações, possivelmente estruturais, sob aquecimento acima de 100&#176C quando um campo elétrico parece produzir uma limpeza elétrica, resultando uma condutividade menor. As polarizações são do tipo t-n, indicando, no caso do PVDF uma distribuição em freqüências e para o FEP tratado termicamente a 200&#176C, uma em energia. Apesar das amostras de PVDF fornecerem resultados pouco reprodutíveis, pode-se concluir que para os campos empregados o comportamento é razoavelmente linear na polarização e superlinear para a condutividade. Observou-se também um comportamento anômalo da corrente, no PVDF, sob a ação prolongada de campo aplicado, mesmo para as menores tensões. Para o FEP o comportamento da corrente para os diversos campos usados foi bastante irregular embora as polarizações e as subseqüentes despolarizações coincidissem na maioria dos casos / We present here the results of electrical measurements performed, most of them, in 25&#956m foils of polyvinylidene fluoride (PVDF), and fewer in flois of tetrafluorethilene-hexafluorpropilene (Teflon FEP). Polarization currents under varied applied voltages and the corresponding depolarizations were measured at constante temperature and during heating and cooling. The PVDF exhibits modifications, possibly its structure changes, if heated above 100&#176C; in this case an electric field seems to clean the sample since its conductivity strongly decreases thereafter. The polarizations are of the t-n type, poiting to a distribution of frequencies inPVDF and of energies in FEP previously annealed at 200&#C. Although the results are poorly reproducible, some conclusions could be drawn for the PVDF: the polarization is nearly linear with the field but the conductivity shows a super linear dependence. An anomalous behavior of the current was observed at long time under tension, even the smallest use here. In the case of FEP, the magnitude of the current in relation with the voltage hás shown an irregular behavior, although polarization and the corresponding depolarization do indeed coincide in most cases

Nesta dissertação relatamos os resultados de medidas elétricas realizadas, a maioria delas, em folhas de 25&#956m de polivinilidene de flúor (PVDF), e em menor número em folhas de tetrafluoretileno-hexafluorpropileno (Teflon FEP). Correntes de polarização sob variadas tensões e de despolarização foram medidas a várias temperaturas e com temperatura variável. O PVDF sofre modificações, possivelmente estruturais, sob aquecimento acima de 100&#176C quando um campo elétrico parece produzir uma limpeza elétrica, resultando uma condutividade menor. As polarizações são do tipo t-n, indicando, no caso do PVDF uma distribuição em freqüências e para o FEP tratado termicamente a 200&#176C, uma em energia. Apesar das amostras de PVDF fornecerem resultados pouco reprodutíveis, pode-se concluir que para os campos empregados o comportamento é razoavelmente linear na polarização e superlinear para a condutividade. Observou-se também um comportamento anômalo da corrente, no PVDF, sob a ação prolongada de campo aplicado, mesmo para as menores tensões. Para o FEP o comportamento da corrente para os diversos campos usados foi bastante irregular embora as polarizações e as subseqüentes despolarizações coincidissem na maioria dos casos / We present here the results of electrical measurements performed, most of them, in 25&#956m foils of polyvinylidene fluoride (PVDF), and fewer in flois of tetrafluorethilene-hexafluorpropilene (Teflon FEP). Polarization currents under varied applied voltages and the corresponding depolarizations were measured at constante temperature and during heating and cooling. The PVDF exhibits modifications, possibly its structure changes, if heated above 100&#176C; in this case an electric field seems to clean the sample since its conductivity strongly decreases thereafter. The polarizations are of the t-n type, poiting to a distribution of frequencies inPVDF and of energies in FEP previously annealed at 200&#C. Although the results are poorly reproducible, some conclusions could be drawn for the PVDF: the polarization is nearly linear with the field but the conductivity shows a super linear dependence. An anomalous behavior of the current was observed at long time under tension, even the smallest use here. In the case of FEP, the magnitude of the current in relation with the voltage hás shown an irregular behavior, although polarization and the corresponding depolarization do indeed coincide in most cases

O poli(fluoreto de vinilideno) (PVDF) é um polímero semicristalino que quando cristalizado a partir da fusão à temperaturas acima de 155°C apresenta uma variada morfologia cristalina, constituída por esferulitos anelados, não anelados e mistos. Abaixo dessa temperatura somente os esferulitos anelados são formados. Neste trabalho foi realizado um estudo morfológico do PVDF, procurando verificar a relação entre o tipo de esferulito formado e a fase cristalina predominante em suas lamelas. Foi verificado, por espectroscopia no infravermelho, que os esferulitos anelados apresentam exclusivamente a fase alfa, quando a cristalização ocorre a temperaturas inferiores a 155°C. Temperaturas superiores a essa induzem nessas estruturas uma transformação de fase alfa em gama, que aumenta a quantidade de fase gama com o tempo de cristalização. A taxa com que essa transformação ocorre aumenta com a temperatura de cristalização. Os esferulitos não anelados são constituídos predominantemente pela fase gama, cristalizada diretamente do fundido, com pequenas inclusões de fase alfa. O processo de fusão dos diferentes esferulitos, observado por microscopia ótica (MOLP) e medidas calorimétricas (DSC), mostraram que a temperatura de fusão da fase gama originada da transformação de fase é 8°C superior à daquela cristalizada diretamente do fundido. Micrografias de amostras aquecidas até 186°C e rapidamente resfriadas permitiram visualizar as regiões dos esferulitos anelados que sofreram a transformação de fase alfa em gama, para diferentes tempos e temperaturas de cristalização. Foi realizado, ainda, um estudo morfológico de blendas PVDF/P(VDF-TrFE), com diferentes composições e com o copolímero contendo 72% em mol de VDF. Análises térmicas (DSC) verificaram que os componentes da blenda são imiscíveis na fase cristalina, quando a cristalização ocorre a partir da fusão. Porém, micrografias obtidas por MOLP e MEV indicaram a presença de moléculas do copolímero nas regiões interlamelares dos esferulitos formados durante a cristalização do PVDF. Esse resultado sugere a miscibilidade entre os componentes no estado líquido, e que esta mistura íntima deve permanecer durante a cristalização, resultando na miscibilidade dos componentes na fase amorfa. / Poly(vinylidene fluoride) (PVDF) is a semi crystalline polymer that, when is crystallized from the melt at temperatures above 155°C, it presents a multiform morphology composed of ringed, non-ringed and mixed spherulites. Above this temperature only ringed spherulites are formed. In this work a morphological study of PVDF was performed, endeavoring to investigate the relation between the type of spherulite formed and the dominant crystalline phase in their lamellas. Infrared spectroscopy showed that the ringed spherulites are formed exclusively by the alpha phase when crystallization takes place at temperatures below 155°C. Higher temperatures induce a solid-state alpha in gamma phase transformation in these structures, increasing the amount of gamma phase with crystallization time. The rate at which this transformation takes place increases with crystallization temperature. The non-ringed spherulites consist predominantly of the gamma phase, crystallized from the melt, with small alpha phase inclusions. The melt process of the different spherulites, observed by optical microscopy (MOLP) and calorimetric measurements (DSC) showed that the melt temperature of the gamma phase originated from the phase transition is 8°C higher than that crystallized directly from the melt. Micrographs of samples heated up to 186°C and quickly cooled allowed visualization of the ringed spherulite regions, which underwent the alpha in gamma phase transformation at different crystallization times and temperatures. In addition, it was observed a morphological study of blends, with different compositions and the copolymer containing 72 mol% of VDF. Thermal analysis (DSC) showed that blend components are immiscible on crystalline phase, when the crystallization from the melt occurs. However, micrographs obtained from MOLP and MEV indicated the presence of copolymer on spherulites interlamellar regions, formed during PVDF crystallization. This result suggests miscibility between the components in the liquid state, and this intimate mixture must remain during crystallization, resulting in miscibility of the components in amorphous phase.