The applications of membrane technologies have dramatically increased during the last few decades due to technology improvement and cost reduction. Membrane applications can be found in water and wastewater treatment, pharmaceutical industry, chemical processing industry, food industry, etc. However, the membrane technology faces two major challenges: membrane fouling and membrane lifetime. During the membrane filtration process, membrane fouling caused by natural organic matter (NOM) is an inevitable phenomenon, and physical cleaning or chemical cleaning are required for recovering the performance of membrane. As a result of these cleaning processes, membrane lifetime is shortened. For this reason, it is necessary to improve membrane's fouling resistance and lifetime in order to apply membrane technology in large-scale facilities. This dissertation focuses on improving the fouling resistance and flux performance of polyvinyl chloride (PVC) membrane and polyvinylidene fluoride (PVDF) membrane. Specifically, it is comprised of four parts. First, I prepared PVC membranes by adding different amounts of amphiphilic copolymer (Pluronic F 127) into PVC casting solutions. I optimized the performance of PVC membranes by changing the amount of Pluronic F127 used in the casting solution. The results show that with the increase of Pluronic F 127 content, the pore size and pore density both decrease. Moreover, the membrane surface becomes more hydrophilic as indicated by lower contact angles. In addition, the PVC membrane exhibits remarkable antifouling characteristics after adding Pluronic F 127. Second, I synthesized PVDF membranes by adding PVDF graft poly(ethylene glycol) methyl ether methacrylate (PEGMA) (PVDF-g-PEGMA) as additive in casting solutions via the phase inversion method. The synthesized PVDF membranes have unique pillar-like structures on surfaces, which gives the PVDF membrane a defect-free feature and allows it to generate high flux under low pressure. Third, I investigated the forming mechanism of the pillar-like structure from aspects of solvent and additive. Finally, I investigated the influence of PEGMA dose on the performance of PVDF membranes. I changed the amount of PEGMA used in the casting solution and compared the performance of the synthesized PVDF membranes. To summarize, this dissertation has deepened our understanding of how to improve the fouling resistance and flux performance of PVC membranes and PVDF membranes by using amphiphilic copolymer. In addition, the PVDF membrane I synthesized has unique pillar-like structures that give it defect-free and high flux properties. Overall, the results of this study provide valuable information for PVC and PVDF membrane synthesis for large-scale production.

Orientador: Marcos David Ferreira / Resumo: Objetivo. Analisar a eficácia antimicrobiana in vitro de compósito em pó a base de prata e sua aplicação em diferentes concentrações em filmes de policloreto de vinila (PVC) produzidos em escala industrial e em laboratório. Métodos. Um material compósito constituído por dióxido de sílicio (SiO2) e nanopartículas de prata (NpAg), produzido e cedido por uma empresa de soluções tecnológicas, foi caracterizado por Microscopia Eletrônica de Varredura (MEV), Espectroscopia no Infravermelho com Transformada de Fourier (FTIR) e Difração de Raio X (DRX). Filmes de PVC industrial aditivados com 6,25, 12,5, 25 e 100 ppm de NpAg e filmes produzidos laboratorialmente pelo método de casting aditivados com 12,5, 25 e 100 ppm de NpAg foram caracterizados por Microscopia Eletrônica de Varredura (MEV), Espectroscopia no Infravermelho com Transformada de Fourier (FTIR) e Difração de Raio X (DRX). Testes microbiológicos in vitro foram realizados com o compósito de prata e com os filmes de PVC. Com o compósito realizou-se o Teste de Difusão em Ágar por poço e a Contagem de Microrganismos Viáveis. Com os filmes industrial e laboratorial realizou-se o teste da Norma JIS Z 2801:2000, e com os filmes industriais realizou-se os testes de Agitação em Frasco e Contagem de Microrganismos Viáveis. Resultados. O compósito apresentou inibição para Escherichia coli em todas as concentrações estudadas e para Staphylococcus aureus nas concentrações de 12,5, 25 e 100 ppm de NpAg. A adição de compósito na matriz... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

<p>Mogućnost primene polivinilhloridnih (PVC) podnih obloga je određena krajnjim svojstvima koja zavise od sastava obloge i načina proizvodnje. Zbog složenog sastava i različitih načina pripreme PVC podnih obloga, veoma je te&scaron;ko tačno proceniti uticaj pojedinačnog procesnog parametara na svojstva dobijenog proizvoda. U ovom radu, da bi se ispitao uticaj sastava polivinilhloridnih sme&scaron;a na svojstva PVC podnih obloga pripremljeno je 27 receptura u kojima su varirane: koncentracije kalcijumkarbonata (40, 70 i 100 phr), koncentracije sredstva za ekspanziju, azodikarbonamida ADC (0,8, 1,0 i 1,2 mas. % u odnosu na ukupnu masu) kao i odnos &bdquo;kikeraˮ i sredstva za ekspanziju, ZnO/ADC (0,33; 0,50 i 0,67). Da bi se proučio uticaj procesnih parametara na svojstva PVC podnih obloga menjani su tehnolo&scaron;ki uslovi proizvodnje: temperatura (180, 184, 188, 192 i 196 &deg;C) i vreme (90, 120 i 150 sekundi) ekspanzije poleđinskog sloja PVC podne obloge. Na taj način je od svake PVC paste dobijeno 15 uzoraka. Za svaki uzorak određena su sledeća svojstva: stepen ekspanzije, zatezna sila pri kidanju, prekidna sila kidanja, zatezno i prekidno izduženje, početni otpor cepanju, otpor cepanju, ukupna deformacija, zaostala deformacija, povratna elastičnost, gustina pene i indeks žućenja. S obzirom na ovako veliki broj podataka urađena je statistička obrada dobijenih eksperimentalnih podataka metodom vi&scaron;estruke linearne regresione analize, kako bi procenili uticaji pojedinačnih procesnih parametara na ispitivana svojstva. Napisan je originalni programski kod primenom Garson-ovog i Yoon-ovog modela u programu Matlab koji omogućava formiranje neuronske mreže i njenu upotrebu u cilju fitovanja eksperimentalnih podataka. Rezultati dobijeni primenom modela po Garson-u nisu pogodni za određivanje uticaja sastava PVC sme&scaron;e i uslova prerade na konačna svojstva proizvoda, jer ne pokazuju pravac uticaja. Dok je ve&scaron;tačka neuronska mreža koja se zasniva na Yoon-ovom modelu uspe&scaron;no primenjena u razvoju novih i pobolj&scaron;anju postojećih svojstava heterogenih PVC proizvoda. Ispitan je i uticaj veličine čestice ZnO koji je upotrebljen kao &bdquo;kikerˮ (sredstvo koje utiče na smanjenje temperature raspada ADC) na svojstva penastih podnih obloga. Napravljene su dve PVC paste, jedna sa komercijalnim ZnO, a druga sa nano ZnO, pri čemu je sastav ostalih komponenti bio identičan. Na osnovu dobijenih eksperimentalnih podatka može se zaključiti da kod uzoraka u kojima je upotrebljen nano ZnO dolazi do intenzivnijeg &bdquo;curenjaˮ gasa nastalog raspadom ADC i međusobnog povezivanja pora. Kao posledica ovakve strukture pora uzorci sa nano ZnO imaju lo&scaron;ija mehanička svojstva. Na osnovu dobijenih karakterističnih temperatura na TG krivama nije uočen uticaj veličine čestica ZnO na termičku stabilnost ispitivanih uzoraka.</p> / <p>The application of PVC floor coverings is strongly connected with their end-use properties which depend on the composition and processing conditions. It is very difficult to estimate the proper influence of production parameters on the characteristics of PVC floor coverings due to their complex composition and various preparation procedures. In this paper, in order to investigate the effect of the PVC mixture composition on the properties of PVC floor coverings, 27 formulations are prepared varying concentration of calcium carbonate (40, 70 and 100 phr), concentration of blowing agent, azodicarbonamide ADC (0.8, 1.0 and 1.2 wt. % relative to the total weight) and the ratio of &quot;kicker&quot; and blowing agent, ZnO/ADC (0.33; 0.50 and 0.67). To study the influence of process parameters on the properties of PVC floor coverings technological production conditions are varied: expansion temperature (180, 184, 188, 192 and 196 &deg;C) and expansion time (90, 120 and 150 seconds) of the PVC floor covering back layer. In this way, 15 samples are made of each PVC paste. The following properties are determined for each sample: expansion ratio, tensile strength, braking strength, tensile extension, breaking extension, initial resistance to tearing, tearing resistance, identation, residual identation, elasticity, density foam and yellowing index. Having such a large amount of data, statistical analysis of experimental data are made with multiple linear regression analysis in order to assess the effects of process parameters on investigated properties. The original program code is written using the Garson&#39;s and Yoon&#39;s models in the Matlab programme that allows the formation of neural networks and its use for the purpose of fitting the experimental data. Results obtained by using the Garson model are not suitable for determining the influence of composition of the PVC mixture and processing conditions on the properties of the final product because it does not show the direction of impact. While the artificial neural network based on Yoon&#39;s model is successfully applied to the development of new as well as to the improvement of the existing properties of the heterogeneous PVC products. The influence of ZnO particle size, used as a&ldquo;kicker&ldquo; (this material reduces the decomposition temperature of ADC) is examined on the properties of the foam flooring. Two PVC pastes are made, one with commercial ZnO and the other with nano ZnO, with the other components of the compositions identical. Based on the obtained experimental data, it can be concluded that there is more intensive gas &bdquo;leak&ldquo; resulting from disintegration of the ADC and also more intensive interconnection of pores in the samples where nano ZnO is used. As a result of this structure of pores, samples with nano ZnO have inferior mechanical properties. Based on the characteristic temperature obtained on TG curves, the influence of ZnO particle size on the thermal stability of the investigated samples is not observed.</p>

Plasty, pronikající do životního prostředí ať už neúmyslně či záměrně, mohou být fragmentovány za vzniku částic v řádu mikrometrů (tzv. mikroplastů) a znečišťovat tak půdní systémy. Doposud vyvinuté analýzy pro stanovení mikroplastů v půdách jsou především zaměřeny na kvalitativní stanovení, nicméně i jejich provedení se zatím stále potýká s různými úskalími. Navíc, téměř všechny tyto analýzy vyžadují časově náročnou předúpravu vzorku. V této studii jsme se zaměřili na vývoj nové analytické metody pro kvantitativní stanovení mikroplastů polyvinylchloridu (PVC) a polystyrenu (PS) v půdách bez předchozí úpravy vzorku pomocí termogravimetrické analýzy spojené s hmotnostní spektrometrií (TGA-MS). Pro analýzu byly použity vzorky modelové půdy s nízkým obsahem organického uhlíku, které byly spikovány na výslednou koncentraci 0,23–7 hm% PVC či PS. Vzorky byly pyrolyzovány s teplotním krokem 5 K min–1 až na teplotu 1000 °C. Pyrolýzní plynné produkty byly následně analyzovány s využitím hmotnostního spektrometru. Získaná data byla normalizována pomocí externího standardu (šťavelan vápenatý). Limity detekce se pohybovaly v rozmezí 0,08–5,3 hm% pro PVC a 0,005–0,7 hm% pro PS v závislosti na zvoleném m/z. Limity kvantifikace pak byly 0,3–17,7 hm% pro PVC a 0,002–2,2 hm% pro PS. Výsledky dokazují, že spojení TGA-MS může být konkurující semikvantitativní metodou pro stanovení mikro-PVC a mikro-PS v půdě s nízkým obsahem organického uhlíku.