Formation mechanism and crystallization of poly(vinylidene fluoride) membrane via immersion precipitation method

Wang, Xuyun; Zhang, Lin; Da-Hai, Sun; An, Quan‐Fu; Chen, Huan-Lin

doi:10.1016/j.desal.2007.10.064

Cited by 99 publications

(56 citation statements)

References 16 publications

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“…Pathway ilar to B but with an even higher RH and a different exposure time. Here, the membrane is ed in the coagulation bath after it crosses the spinodal line [21] moving from path C to E. like the NIPS process, in which introducing the cast film into the coagulation bath promotes aneous demixing (Figure 1), slow uptake of water from humid air allows the composition to cross or approach the crystallization region in the phase diagram ( Figure 2) and form line morphology, allowing the crystal nuclei to grow thanks to the semi-crystalline property F, as observed in the case of VIPS-37%, VIPS-60% and VIPS-80% in Figure 1 [23]. This way, nuclei were formed and they had sufficient time to grow and produce a spherulitic structure resulting membrane as illustrated in Figure 1.…”

Section: Membrane Morphologies In Nips Vs Vipsmentioning

confidence: 99%

Improving Liquid Entry Pressure of Polyvinylidene Fluoride (PVDF) Membranes by Exploiting the Role of Fabrication Parameters in Vapor-Induced Phase Separation VIPS and Non-Solvent-Induced Phase Separation (NIPS) Processes

AlMarzooqi¹,

Bilad²,

Arafat³

2017

Applied Sciences

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Polyvinylidene fluoride (PVDF) is a popular polymer material for making membranes for several applications, including membrane distillation (MD), via the phase inversion process. Non-solvent-induced phase separation (NIPS) and vapor-induced phase separation (VIPS) are applied to achieve a porous PVDF membrane with low mass-transfer resistance and high contact angle (hydrophobicity). In this work, firstly, the impacts of several preparation parameters on membrane properties using VIPS and NIPS were studied. Then, the performance of the selected membrane was assessed in a lab-scale direct-contact MD (DCMD) unit. The parametric study shows that decreasing PVDF concentration while increasing both relative humidity (RH) and exposure time increased the contact angle and bubble-point pore size (BP). Those trends were investigated further by varying the casting thickness. At higher casting thicknesses and longer exposure time (up to 7.5 min), contact angle (CA) increased but BP significantly decreased. The latter showed a dominant trend leading to liquid entry pressure (LEP) increase with thickness.

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Section: Membrane Morphologies In Nips Vs Vipsmentioning

confidence: 99%

Improving Liquid Entry Pressure of Polyvinylidene Fluoride (PVDF) Membranes by Exploiting the Role of Fabrication Parameters in Vapor-Induced Phase Separation VIPS and Non-Solvent-Induced Phase Separation (NIPS) Processes

AlMarzooqi¹,

Bilad²,

Arafat³

2017

Applied Sciences

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“…The ternary phase diagrams of different casting solution were obtained through cloud point titration measurements as reported in previous literature [15][16][17]. The cloud point data were measured through titration method by adding water slowly into the polymer dope under vigorous agitation at 25 °C.…”

Section: Ternary Phase Diagram Of Ppta-pvdf/nmp/water Systemmentioning

confidence: 99%

Effects of Additives on the Morphology and Performance of PPTA/PVDF in Situ Blend UF Membrane

Shi

Zhang

et al. 2014

Polymers

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Poly(p-phenylene terephtalamide) (PPTA), a high-performance polymer with high modulus and good hydrophilicity, is often used as a reinforced material. However, due to its high crystallity, micro-phase separation often occurs in the blends. In this paper, PPTA/poly(vinylidene fluoride) (PVDF) compatible blend solution was synthesized by in situ polycondensation. Blend ultra-filtration membrane was prepared through the immersion phase inversion process. In order to obtain desired pore structure, the effects of different additives including hydrophilic polymer (polyethylene glycol (PEG)), inorganic salt (lithium chloride (LiCl)) and the surfactant (Tween-80) on the morphology and performance of PPTA/PVDF blend membranes were studied. The membrane formation process was investigated through ternary phase diagram (thermodynamics) and viscosities (kinetics) analysis. It was found that, with the increasing of LiCl content, a porous membrane structure with long finger-like pores was formed due to the accelerated demixing process which resulted in the increase of porosity and pore diameter as well as the enhancement of water flux and the decline of PEG rejection. When Tween content increased to over 3 wt%, dynamic viscosity became the main factor resulting in a decreased phase separation rate. The transfer of PEG and LiCl molecules onto membrane surface increased the surface hydrophilicity. The effect of Tween content on membrane hydrophilicity was also correlated with the compatibility of blend components.

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“…A porosidade foi determinada pela imersão das membranas em n-octanol durante 24 horas e calculada pela Equação 3 [13] : Tabela 1. Percentual de perda de massa apresentada pelas membranas em diferentes soluções.…”

Section: Determinação Da Densidade E Porosidadeunclassified

Preparação e caracterização de membranas poliméricas a partir da blenda polisulfona/poliuretano

Bellincanta¹,

Poletto²,

Thürmer³

et al. 2011

Polímeros

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Resumo: Membranas de polisulfona/poliuretano foram preparadas pelo método de inversão de fases. As membranas preparadas com a adição de fotoiniciador foram irradiadas com lâmpada ultravioleta para aumentar a interação entre os polímeros e o suporte de poliéster utilizado. As membranas com e sem adição de fotoiniciador foram caracterizadas através dos testes de resistência química, capacidade de adsorção de água, determinação de densidade, porosidade, morfologia e fluxo permeado de água. A membrana fotoiniciada apresentou poros com paredes bem definidas e maior estabilidade nos testes de resistência química e fluxo permeado. Ambas as membranas apresentaram valores aproximados na adsorção de água e porosidade. Palavras-chave: Membranas poliméricas, poliuretano, polisulfona, inversão de fase. Preparation and Characterization of Polymeric Membranes from Blended Polysulfone/PolyurethaneAbstract: Polysulfone/polyurethane membranes were prepared by the phase inversion method and irradiated with an ultraviolet light bulb to increase the interaction between polymers and the polyester support. The membranes with and without addition of fotoinitiator were characterized using tests of chemical resistance, water adsorption capacity, density and porosity determination, water permeate flux and membrane morphology. The membrane treated with the fotoinitiator exhibited well defined pores and greater stability in the tests of chemical resistance and water permeate flux. Both membranes had similar values for the water adsorption and porosity. Keywords: Polymeric membranes, poly(urethane), poly(sulfone), inversion phase. IntroduçãoA inversão de fases é um dos processos mais importantes para preparação de membranas poliméricas simétricas e assimétricas [1] . Neste processo, a solução polimérica homogênea é separada em duas fases: uma fase sólida rica em polímero, a qual forma a matriz da membrana e uma fase líquida pobre em polímero a qual forma a estrutura porosa [2,3] . Após a imersão do filme polimérico no banho de coagulação contendo o não-solvente, este irá difundir para a solução polimérica, enquanto o solvente se difundirá no banho. A força motriz para este processo é a diferença de potencial químico existente entre o filme e o banho [4] . A transferência de massa entre o solvente e o não solvente é um fator determinante na morfologia das membranas e para a compreensão dos fenômenos envolvidos na síntese das mesmas [5] . As membranas obtidas por inversão de fases são usadas atualmente em muitas aplicações como a microfiltração, ultrafiltração, osmose inversa e como suporte para membranas compósitas.Alguns dos polímeros mais utilizados na produção de membranas assimétricas, os quais são utilizados neste trabalho são a polisulfona (PSO) e o poliuretano (PU). Membranas de PSO preparadas pelo método de inversão de fase possuem boa resistência mecânica, alta resistência ao calor e elevada estabilidade química sendo amplamente usadas em processos de ultrafiltração e como suporte para membranas compósitas aplicadas em nanofiltraç...

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Formation mechanism and crystallization of poly(vinylidene fluoride) membrane via immersion precipitation method

Cited by 99 publications

References 16 publications

Improving Liquid Entry Pressure of Polyvinylidene Fluoride (PVDF) Membranes by Exploiting the Role of Fabrication Parameters in Vapor-Induced Phase Separation VIPS and Non-Solvent-Induced Phase Separation (NIPS) Processes

Improving Liquid Entry Pressure of Polyvinylidene Fluoride (PVDF) Membranes by Exploiting the Role of Fabrication Parameters in Vapor-Induced Phase Separation VIPS and Non-Solvent-Induced Phase Separation (NIPS) Processes

Effects of Additives on the Morphology and Performance of PPTA/PVDF in Situ Blend UF Membrane

Preparação e caracterização de membranas poliméricas a partir da blenda polisulfona/poliuretano

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