Την τελευταία δεκαετία, η επεξεργασία υφασμάτων με πλάσμα έχει αποκτήσει μεγάλο τεχνολογικό ενδιαφέρον καθώς μπορεί να χρησιμοποιηθεί σε διάφορα στάδια της επεξεργασίας. Η οξείδωση της επιφάνειας, η ενίσχυση της υδροφιλίας ή της υδροφοβικότητας της και η αντιμικροβιακή δράση, είναι κάποια παραδείγματα τέτοιων εφαρμογών. Τα πλεονεκτήματα της τεχνικής του πλάσματος σε σύγκριση με άλλες τεχνικές είναι ότι είναι φιλική προς το περιβάλλον και ταυτόχρονα οικονομική αφού μειώνει τις απαιτήσεις σε νερό και ενέργεια. Παρόλα αυτά δεν υπάρχουν στη βιβλιογραφία επαρκείς μελέτες σχετικά με τους βασικούς μηχανισμούς που διέπουν τη διεργασία. Σε αυτή την κατεύθυνση επικεντρώσαμε στη μελέτη της επίδρασης του πλάσματος He/O2 σε χαμηλές πιέσεις με στόχο την ενίσχυση της υδροφιλίας της επιφάνειας, στη διερεύνηση της επίδρασης του C2F6 πλάσματος για την ενίσχυση της υδροφοβικότητας καθώς και στο σχηματισμό PEO-like υμενίων για την βελτίωση της αντιμικροβιακής δράσης της επιφάνειας. Πιο συγκεκριμένα, μελετήθηκε η επίδραση του ποσοστού οξυγόνου στο μείγμα του αερίου, του χρόνου επεξεργασίας, της συνολικής πίεσης και της ισχύος του πλάσματος στην μεταβολή των επιφανειακών ιδιοτήτων και κυρίως στην ενίσχυση της υδροφιλικότητας πολυεστερικών υφασμάτων πριν και μετά από το αποκολλάρισμα τους. Για τη μελέτη της υδροφοβικότητας πραγματοποιήθηκαν πειράματα ως προς την συνολική πίεση, το χρόνο διεργασίας και την απόσταση των ηλεκτροδίων. Τέλος, για την ενίσχυση της αντιμικροβιακής δράσης της επιφάνειας μελετήθηκε η συνολική πίεση, η ισχύς καθώς και το ποσοστό του οξυγόνου στο μίγμα. Οι αλλαγές που λαμβάνουν χώρα στην αέρια φάση και ο πιθανότερος μηχανισμός στον οποίο οφείλονται οι αλλαγές στην επιφάνεια του υποστρώματος μελετήθηκαν με την εφαρμογή διαγνωστικών τεχνικών του πλάσματος. Έτσι ηλεκτρικές μετρήσεις πραγματοποιήθηκαν για τον υπολογισμό της καταναλισκόμενης ισχύος και της εμπέδησης της εκκένωσης ενώ παράλληλα, πραγματοποιήθηκαν οπτικές μετρήσεις με στόχο την καταγραφή των ειδών που παράγονται στην εκκένωση και την κατανομή τους στον χώρο. Από την άλλη μεριά για τη μελέτη των δομικών και φυσικοχημικών μεταβολών που υφίσταται η επιφάνεια κατά την επεξεργασία της με πλάσμα χρησιμοποιήθηκαν ηλεκτρονιακή μικροσκοπία σάρωσης και φασματοσκοπία φωτοηλεκτρονίων από ακτίνες Χ. Τέλος, μετρήσεις του ρυθμού απορρόφησης σταγόνας, γωνίες αδιαβροχίας και προσρόφηση πρωτεϊνών χρησιμοποιήθηκαν ως μέτρο εκτίμησης της υδροφιλίας, της υδροφοβικότητας και της αντιμικροβιακής δράσης αντίστοιχα. Τα βέλτιστα αποτελέσματα παρουσιάζονται και συζητούνται σαν συνάρτηση των ιδιοτήτων του πλάσματος / The last decade, the treatment of polyester textiles using plasma techniques has gained a lot of technological interest. The surface oxidation, the enhancement of hydrophilicity/hydrophobicity and the deposition of antibacterial films are examples of technological plasma applications. The benefits of using the plasma techniques are enormous. The major ones are that is an environmental friendly method and at the same time is economical due to the reduction of energy and water consumption. Although, in the bibliography there are not sufficient studies relevant to the basic mechanism of the plasma treatment/deposition. In this direction, we focused our study on the effect of plasma He/O2 treatment in low values of pressure, targeting the enhancement of surface hydrophilicity, on the deposition conditions of Teflon-like and peo-like films, targeting the enhancement of hydrophobicity and antibacterial effect respectively. In more details, it was examined the effect of oxygen percentage in He/O2 mixture, the discharge time, the total pressure and the power in the alteration of surface properties. Furthermore, experiments were implemented in different pressure, discharge time, power and distance electrode conditions in order to achieve better hydrophobicity. At last, as far as the deposition of peo-like coatings were concerned, power, pressure and oxygen percentage were parameters under investigation. The alterations which took place in the gas phase and the most possible treatment/deposition mechanism were studied using diagnostic techniques such as electrical and optical measurements. On the other hand, for the investigation of physicochemical alterations on the surface, measurements such as xps, water droplet absorption and WCA were implemented. The best results are presented and are discussed as a function of plasma properties.

Made available in DSpace on 2014-06-11T19:35:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-07-29Bitstream added on 2014-06-13T20:26:08Z : No. of bitstreams: 1 lazarin_aa_dr_arafo.pdf: 2142552 bytes, checksum: 63a785fe41ed3de17382a8e94e97b844 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Foi proposto avaliar diferentes vernizes experimentais, que apresentam em sua formulação monômeros hidrofílicos ou zwiteriônicos, como método para modificar a superfície de resina acrílica para base de prótese, com o objetivo de prevenir a adesão de C. albicans. Foram confeccionados corpos-de-prova com características superficiais que simulavam a parte polida das próteses (superfície lisa) e com características superficiais que simulavam a parte interna das próteses (superfície rugosa) utilizando-se uma resina para base de prótese específica para micro-ondas (Vipi Wave). Matrizes metálicas com 10 cavidades (13,8 mm de diâmetro e 2 mm de altura) foram incluídas em mufla, entre 2 placas de vidro, para simular a superfície lisa, ou em contato com gesso para obter amostras que simulassem a superfície rugosa da prótese. Todos os corpos-de-prova foram submetidos à mensuração da rugosidade utilizando-se um rugosímetro (Mitutoyo SJ 400) com cutoff de 2,5 mm. A rugosidade superficial foi determinada (Ra-µm) pela média de três mensurações realizadas em cada amostra. Após a leitura da rugosidade, os corpos-de-prova foram divididos em grupo controle (n=72; 36 lisos e 36 rugosos), não recebendo nenhum tratamento superficial, e 12 grupos experimentais (n=72; 36 lisos e 36 rugosos) que receberam uma camada do verniz experimental sendo polimerizado em forno EDG. Os vernizes experimentais apresentaram em sua composição o monômero metil metacrilato (MMA), dois agentes de ligação cruzada (TEGDMA e Bis-GMA) e o foto iniciador MBP (4- metil benzofenona). Além desses componentes, os vernizes identificados pelos códigos P, E e T apresentaram monômeros hidrofílicos em 3 concentrações (25, 30 e 35%). O verniz identificado pelo código M apresentou um monômero zwiteriônico (MZ), nas mesmas... / The aim of the present study was to evaluate the use of different experimental varnishes containing zwitterion or hydrophilic monomers as a manner to modify the surface characteristics of a denture base resin and prevent the adhesion of C. albicans. For such purpose, specimens with surface characteristics that simulated the polished side of the dentures and the inner side of the dentures were fabricated using a microwave-polymerized denture base acrylic resin (Vipi Wave). Hollow metallic matrices with 10 cavities (13.8 mm diameter x 2 mm high) were flasked either between two glass plates, in order to produce specimens with smooth surfaces that simulated the polished side of the dentures, or in direct contact with the stone, in order to obtain specimens with rough surfaces that simulated the inner side of the dentures. All specimens were subjected to surface roughness readings in a roughness meter (Mitutoyo SJ 400) with cutoff length of 2.5 mm. Surface roughness (Ra, µm) was determined as the average of three random measurements made on each specimen. After the roughness readings, the specimens were randomly assigned to one control group (n=72; 36 smooth and 36 rough specimens), in which the specimens received no surface treatment, and 12 experimental groups (n=72; 36 smooth and 36 rough specimens) in which the specimens were coated with one of the experimental varnishes followed by polymerization in an EDG oven. The 12 experimental varnishes presented in their composition the monomer methyl methacrylate (MMA), two crosslinking agents (TEGDMA and Bis-GMA) and a photoinitiator agent (4-methyl benzophenone . MPB). In addition to these components, the experimental varnishes labeled as P, E and T presented hydrophilic monomers at three concentrations (25, 30 and 35%). The experimental varnish labeled as M presented a zwitterion... (Complete abstract click electronic access below)

Resumo: Foi proposto avaliar diferentes vernizes experimentais, que apresentam em sua formulação monômeros hidrofílicos ou zwiteriônicos, como método para modificar a superfície de resina acrílica para base de prótese, com o objetivo de prevenir a adesão de C. albicans. Foram confeccionados corpos-de-prova com características superficiais que simulavam a parte polida das próteses (superfície lisa) e com características superficiais que simulavam a parte interna das próteses (superfície rugosa) utilizando-se uma resina para base de prótese específica para micro-ondas (Vipi Wave). Matrizes metálicas com 10 cavidades (13,8 mm de diâmetro e 2 mm de altura) foram incluídas em mufla, entre 2 placas de vidro, para simular a superfície lisa, ou em contato com gesso para obter amostras que simulassem a superfície rugosa da prótese. Todos os corpos-de-prova foram submetidos à mensuração da rugosidade utilizando-se um rugosímetro (Mitutoyo SJ 400) com cutoff de 2,5 mm. A rugosidade superficial foi determinada (Ra-µm) pela média de três mensurações realizadas em cada amostra. Após a leitura da rugosidade, os corpos-de-prova foram divididos em grupo controle (n=72; 36 lisos e 36 rugosos), não recebendo nenhum tratamento superficial, e 12 grupos experimentais (n=72; 36 lisos e 36 rugosos) que receberam uma camada do verniz experimental sendo polimerizado em forno EDG. Os vernizes experimentais apresentaram em sua composição o monômero metil metacrilato (MMA), dois agentes de ligação cruzada (TEGDMA e Bis-GMA) e o foto iniciador MBP (4- metil benzofenona). Além desses componentes, os vernizes identificados pelos códigos P, E e T apresentaram monômeros hidrofílicos em 3 concentrações (25, 30 e 35%). O verniz identificado pelo código M apresentou um monômero zwiteriônico (MZ), nas mesmas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of the present study was to evaluate the use of different experimental varnishes containing zwitterion or hydrophilic monomers as a manner to modify the surface characteristics of a denture base resin and prevent the adhesion of C. albicans. For such purpose, specimens with surface characteristics that simulated the polished side of the dentures and the inner side of the dentures were fabricated using a microwave-polymerized denture base acrylic resin (Vipi Wave). Hollow metallic matrices with 10 cavities (13.8 mm diameter x 2 mm high) were flasked either between two glass plates, in order to produce specimens with smooth surfaces that simulated the polished side of the dentures, or in direct contact with the stone, in order to obtain specimens with rough surfaces that simulated the inner side of the dentures. All specimens were subjected to surface roughness readings in a roughness meter (Mitutoyo SJ 400) with cutoff length of 2.5 mm. Surface roughness (Ra, µm) was determined as the average of three random measurements made on each specimen. After the roughness readings, the specimens were randomly assigned to one control group (n=72; 36 smooth and 36 rough specimens), in which the specimens received no surface treatment, and 12 experimental groups (n=72; 36 smooth and 36 rough specimens) in which the specimens were coated with one of the experimental varnishes followed by polymerization in an EDG oven. The 12 experimental varnishes presented in their composition the monomer methyl methacrylate (MMA), two crosslinking agents (TEGDMA and Bis-GMA) and a photoinitiator agent (4-methyl benzophenone . MPB). In addition to these components, the experimental varnishes labeled as P, E and T presented hydrophilic monomers at three concentrations (25, 30 and 35%). The experimental varnish labeled as M presented a zwitterion... (Complete abstract click electronic access below) / Orientador: Ana Lucia Machado / Coorientador: Carlos Eduardo Vergani / Banca: Ana Cláudia Pavarina / Banca: Marco Antonio Compagnoni / Banca: Dalva Cruz Laganá / Banca: Cláudia Helena Lovato da Silva / Doutor

Isoladores poliméricos têm crescentemente competido com os isoladores cerâmicos nas aplicações em sistemas elétricos de potência e é esperado que dominem as aplicações externas em alta tensão em um futuro próximo. Entretanto, há ainda algumas questões pendentes acerca do envelhecimento dos polímeros sobre estresse elétrico e climático. Dessa forma, a estabilidade da hidrofobicidade deve ser medida para estender o tempo de vida do isolador. Por esta razão, o desenvolvimento de um sistema de medição da degradação tem se tornado um fator relevante. Este trabalho apresenta e discute o desenvolvimento de um sistema para avaliação da hidrofobicidade em materiais poliméricos. São também discutidos os testes realizados em novas resinas derivadas do óleo de mamona. / Polymeric isolators have been competing increasingly with ceramic isolators in electric power system applications and is expected to dominate in the near future high voltage outdoor applications. However, there are still some outstanding questions regarding aging of polymers under climatic and electrical stresses. In this way, hydrophobicity has to been measured for to extend the life time of these insulators. For these reasons, the development of a degradation measurement system has become a relevant factor. This work presents and discusses the development of a hydrophobicity estimation system to polymeric materials. Also discussed are the tests carried out on the new castor oil resin.

Orientador: José Pissolato Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-24T06:21:09Z (GMT). No. of bitstreams: 1 Abreu_SandersonRochade_M.pdf: 5297087 bytes, checksum: ef0820d93a3ed019ef6405a29a95a6c0 (MD5) Previous issue date: 2013 / Resumo: Os sistemas elétricos estão submetidos esporadicamente a várias formas de fenômenos transitórios, envolvendo variações súbitas de tensão e de corrente provocadas por descargas atmosféricas, faltas no sistema ou operação de disjuntores e chaves seccionadoras. Desta forma, os equipamentos elétricos além de estarem permanentemente solicitados pela tensão de operação dos sistemas, serão eventualmente submetidos por solicitações de tensões temporárias e transitórias, provenientes da ocorrência de distúrbios nos sistemas. A utilização de para-raios em sistemas de distribuição é uma prática que as empresas distribuidoras de energia elétrica vêm utilizando ao longo dos anos, para limitar as amplitudes das sobretensões transitórias de origem atmosférica nos sistemas de distribuição, reduzindo os efeitos dessas sobretensões sobre os equipamentos a níveis aceitáveis, de modo a aumentar a confiabilidade do sistema. Para isso, é imprescindível que os para-raios estejam operacionais ao longo de toda a sua vida útil e que resistam às diversas solicitações de tensões temporárias e transitórias sob diferentes condições ambientais. Este trabalho, pretende avaliar o comportamento dos diferentes projetos construtivos de para-raios de distribuição disponíveis no mercado nacional e internacional, mediante a avaliação sob condições de temperatura, umidade e precipitação pluviométrica, por meio de envelhecimento acelerado. Pretende fornecer subsídios que possam nortear escolhas importantes a serem tomadas pelas concessionárias de distribuição de energia elétrica do Grupo Energisa, como por exemplo, a seleção do equipamento adequado às condições climáticas de cada região atendida. A análise da hidrofobicidade dos polímeros utilizados na construção do para-raios tem um papel importante neste trabalho, pois poderá indicar a possível degradação do invólucro de acordo com as condições ambientais que este está exposto por região do Brasil, onde o Grupo Energisa tem atuação / Abstract: The eletrical systems are sporadically submitted to several forms of transient phenomena involving sudden changes in voltage and current caused by atmospheric surges, system faults or operating circuit breakers and switchgear. Thus, electrical equipment in addition to being permanently operating voltage required by the systems, are eventually submitted to requests for temporary and transient voltages, from the ocurrence of systems disturbances. The use of surge arresters in distribution systems is a practice that the electricity distribution companies have used over the years to limit the amplitudes of transient overvoltages of atmospheric origin in distribution systems and reducing the effects of these overvoltages on equipment at acceptable levels in order to increase system reliability. Therefore, it is necessry that surge arresters are operational throughout its life and resistant to several requests of temporary and transient voltages under different environmental conditions. This work intends to evaluate the behavior of different constructive projects of surge arresters distribution available on the national and international markets, through their evaluation under conditions of temperature, humidity and rainfall, through accelerated aging. Also intends to provide subsidies to orient important choices to be made by electricity distribution companies from Energisa Group, for example, the selection of appropriate climatic conditions equipment of each region served. For this, the analysis of the hydrophobicity of the polymers used in the construction of surge arresters, plays an important role in this work , as it may indicate the possible deterioration of the housing according to the environmental conditions that are exposed by the region of Brazil, where the Group Energisa has operations / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica

Doctor of Philosophy / Department of Grain Science and Industry / X. Susan Sun / Oilseed protein is a promising renewable source to be used as the replacement of petroleum-based materials for adhesion purpose, and it has drawn increasing attention since soy-based adhesives were developed for wood glues. However, soy protein comprises a portion of humans’ diets, thereby creating competition between utilization of soy protein for protein-based products or human food. Therefore, alternative bio-resources must be discovered. Proteins from camelina sativa provide such potential. Similar to other protein-based polymers, low mechanical strength and poor water resistance are the major drawbacks limiting camelina protein’s further applications. In this research, camelina protein (CP) was modified by unfolding, crosslinking, and co-polymerization treatment for improved flow-ability, adhesion properties and water resistance, which facilitates the industrialization of camelina as an alternative to soy-based adhesives. The physicochemical properties and microstructures of CP were also investigated. To increase the reactivity of CP adhesive, the first step is to denature the folded structure of native proteins. Camelina protein was extracted from defatted camelina meal through alkali solubilization and acid precipitation and modified with varying amount of NaHSO₃ (0-12% of the protein dry base) and Gdm.Cl (0-250% of the protein dry base). NaHSO₃ treatment broke the disulfide bonds of the CP and thus increased its free sulfhydryl content and surface hydrophobicity. As NaHSO₃ concentration increased, the viscosity, elastic modulus (G') and water resistant of NaHSO₃-modified camelina protein (SMCP) dispersion decreased, and the protein became hydrophobic. Gdm.Cl treatment broke the CPI’s hydrogen bonds but decreased their surface hydrophobicity. Similarly, viscosity, G', and water resistant of Gdm.Cl-modified camelina protein (GMCP) dispersions decreased as Gdm.Cl increased and protein became to aggregate. The reducing effect of NaHSO₃ was more obvious than Gdm.Cl to disrupt CPI’s intermolecular protein interaction but less obvious than Gdm.Cl to reduce the viscosity and water resistant. To further increase the CP’s water resistance, a coupling agent, Ethyl-3-(3-dimethyl-aminopropyl-1-carbodiimide) (EDC), was applied to stabilize the protein structure by crosslinking the free carboxyl groups and amino groups. The cross-linked CP exhibited increased molecular weight and particle size. Microstructures of modified CP also became rigid and condensed. Accordingly, CP’s increased intermolecular protein interaction resulted in its higher elastic modulus, viscosity and water resistance. The ultrasound pretreatment further increased the crosslink degree of CP, which resulted in protein’s increased aggregation behaviors and compact micro-structures. Consequently, the elastic modulus, viscosity, and water resistance of CP increased accordingly. Copolymerization with hydrophobic enhancers was also an effective method to improve CP’s water resistance. In this study, kraft lignin was oxidized by H₂O₂ and then copolymerized with CP as wood adhesives, which exhibited increased wet strength. In the presence of ultrasound irradiation, the H₂O₂-depolymerized kraft lignin exhibited reduced particle size, thermal stability and increased content of hydroxyl groups. Fluorescence spectroscopy analysis revealed that after coupling with pristine or de-polymerized lignin, CP exhibited increased hydrophobicity due to lignin’s increased reactivity with camelina protein. Accordingly, the water resistance of CP-based adhesives improved. In the optimized condition, when CP was copolymerized with ultrasound-induced oxidized lignin, it had increased wet shear adhesion strength from 0.28 MPa to 1.43 MPa, with wood panels passing the three-cycle water soaking test.

The hydrophobic interaction refers to a mutually attractive force experienced by hydrophobic surfaces or molecules across water. At the molecular scale, it drives the selfassembly of lipid vesicles and micelles and accelerates interfacial chemical reactions. At the macroscale, it confers upon numerous plants and insects the ability to repel water and is harnessed in practical applications, such as water-proofing and desalination. However, despite its ubiquity and significance, mechanistic insights into the hydrophobic interaction between macroscopic surfaces remain unclear. A significant body of experimental data on surface force measurements exists, which were obtained following this protocol: hydrophobic molecules (typically organosilanes) are physisorbed onto molecularly smooth mica films that are glued onto transparent rigid silica discs and driven towards each other while measuring forces and distances. We developed a protocol for functionalizing mica surfaces with perfluorodecyltrichlorosilane (FDTS) to achieve robust, ultra-smooth hydrophobic surfaces. Then we investigated the consequences of nuclear quantum effects (NQEs) in water on the hydrophobic interaction. Whereas NQEs are known to influence physical and chemical properties of water, their impact on the hydrophobic interaction has remained largely unexplored. We find that the attractive forces between FDTS-coated mica surfaces were ~ 10% higher in light water (H2O) than in heavy water (D2O) even though macroscopic measurables, such as the interfacial tensions and contact angles are indistinguishable. This is the first-ever experimental demonstration of nuclear quantum effects at play in modulating hydrophobic surface forces. Towards practical applications, we investigated the partitioning of small, amphiphilic molecules onto our molecularly smooth FDTS-coated mica films. These scenarios are relevant in wastewater treatment, bioresource processing, fermenter broths, and food & beverage industries. Water-soluble short chain alcohols (ethanol) readily partitioned onto FDTS surfaces and remained attached onto the surface. The presence of alcohols was confirmed by surface force measurements, contact angle goniometry of water drops, and gas chromatography. We investigated protocols for characterizing fouled surfaces and cleaning them. These protocols were tested on realistic desalination membranes and proved effective. Thus, our findings could be used to develop robust protocols for characterizing membrane fouling and cleaning protocols in various separation processes.

The main topic of the thesis was to examine the hydrophobicity of labeling adhesives in the state before drying, it means their resistance against condensated moisture. The problem was solved by measuremensts of contact angle between the drop of water and glue. Measurements of dynamic viscosity and wet tack were also performed for the sake of complex characterization of the glue properties. Comparison of properties among single-component adhesives based on the acrylic copolymers alkalised with various agents was made. The impact of starches and industrial additives on glues was determined by the analysis of primary physical and chemical parameters. The purpose of the measurements was to develop a formula of the glue with enhanced atmospheric moisture resistance, that also would have the required parameters in the equilibrium. Finally, some selected glue samples were practically tested for condensation water resistance. These tests were performed in a climatic chamber with water condensating conditions.

In this work we study the deposition of hydrophobic fluorocarbon coatings by magnetron sputtering of polymeric PTFE target. We show what is the influence of the conditions of the deposition process - the pressure in the chamber, the RF power - on the properties of the resulting CFx thin films (their chemical composition, morphology, wettability, barrier and optical properties, stability and possible bio-aplications). In this work we use a novel way to control the morphology and the chemical composition of the surface of thin films independently by using nano-particles, both metal (Pt, Cu, Al) and polymeric (C:H, Nylon). With nano-particles we can control the hydrophobicity of thin films and we can prepare super-hydrophobic films. Work has an experimental character.

Membrane bioreactors (MBRs) offer promising solution for wastewater treatment and reuse to address the problem of water scarcity. Nevertheless, this technology is still facing challenges associated with membrane biofouling. This phenomenon has been mainly investigated in lab-scale MBRs with little or no insight on biofouling in full-scale MBR plants. Furthermore, the temporal dynamics of biofouling microbial communities and their extracellular polymeric substances (EPS) are less studied. Herein, a multidisciplinary approach was adopted to address the above knowledge gaps in lab- and full-scale MBRs. In the full-scale MBR study, 16S rRNA gene pyrosequencing with multivariate statistical analysis revealed that the early and mature biofilm communities from five full-scale MBRs differed significantly from the source community (i.e. activated sludge), and random immigration of species from the source community was unlikely to shape the community structure of biofilms. Also, a core biofouling community was shared between the five MBR plants sampled despite differences in their operating conditions. In the lab-scale MBR studies, temporal dynamics of microbial communities and their EPS products were monitored on different hydrophobic and hydrophilic membranes during 30 days. At the early stages of filtration (1 d), the same early colonizers belonging to the class Betaproteobacteria were identified on all the membranes. However, their relative abundance decreased on day 20 and 30, and sequence reads belonging to the phylum Firmicutes and Chlorobi became dominant on all the membranes on day 20 and 30. In addition, the intrinsic membrane characteristic did not select any specific EPS fractions at the initial stages of filtration and the same EPS foulants developed with time on the hydrophobic and hydrophilic membranes. Our results indicated that the membrane surface characteristics did not select for specific biofouling communities or EPS foulants, and the same early colonizers were selected from the source community (i.e. activated sludge), and then went through significant changes to form a mature biofilm. Our findings from these studies could support future research aimed at developing enhanced biological-based strategies to control biofouling in MBRs.