Free volume and water vapor permeability of dense segmented polyurethane membrane

Mondal, Subrata; Hu, Jinlian; Yong, Zheng

doi:10.1016/j.memsci.2006.01.047

Cited by 111 publications

(57 citation statements)

References 20 publications

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“…In addition to that, Chen et al also investigated adjusting the size and shape of the free-volume holes in a fabricated membrane to control the WVP by adjusting the temperature [59]. Further, Mondal and Hu attempted to find the influence of hydrophilic groups and crystalline soft segments on the WVP of SMPU films [60]. They found that the WVP increased with the increase of PEG due to the enhancement of hydrophilicity.…”

Section: Textile Application Of Smpumentioning

confidence: 99%

Polyurethane: A Shape Memory Polymer (SMP)

Thakur¹,

Hu²

2017

Aspects of Polyurethanes

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Shape memory polymer (SMP) is a stimuli-responsive material with the ability to alter a programmed shape to its original shape upon triggering of an appropriate stimulus. For the past decades, SMP has dragged much interest in material field owing to its various and versatile applications. One archetypal SMP is polyurethane, which has a wideranging transition temperature for its shape recovery, retraction temperatures, inherent soft-hard segments, a high recoverable strain (up to 400%), high control of the softening, favorable and tunable physical properties, and so on. This chapter emphasizes on the raw materials required for the synthesis of shape memory polyurethane (SMPU), the principle of shape memory function, the design of protocol of SMPU, and their applications with future directions.

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Section: Textile Application Of Smpumentioning

confidence: 99%

Polyurethane: A Shape Memory Polymer (SMP)

Thakur¹,

Hu²

2017

Aspects of Polyurethanes

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“…Among them, shape memory alloys (SMAs) and shape memory polymers (SMPs) are the most important ones at present, and their efficacy is strictly connected to their final application [10]. They have been widely applied as smart textiles and apparels [11], intelligent medical devices [12], heat shrinkable packages for electronics [13], high performance water-vapor permeability materials [14], self-deployable structures [15], and microsystems [16]. SMPs can recover their original (or permanent) shapes under appropriate external stimuli, such as heating [1,8,16,17], cooling [18], light [19,20], electric field [21][22][23][24][25][26], magnetic field [27][28][29], water [30], pH, specific ions or enzyme [31].…”

mentioning

confidence: 99%

Electrically conductive epoxy nanocomposites containing carbonaceous fillers and in-situ generated silver nanoparticles

Dorigato¹,

Giusti²,

Bondioli³

et al. 2013

Express Polym. Lett.

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Abstract. An epoxy resin was nanomodified with in-situ generated silver nanoparticles (Ag) and with various amounts of carbon black (CB) and carbon nanofibers (NF), in order to increase the electrical conductivity of the matrix. Differential scanning calorimetry tests revealed how the addition of both CB and NF led to a slight decrease of the glass transition temperature of the material, while electron microscopy evidenced how the dimension of CB aggregates increased with the filler content. Both flexural modulus and stress at yield were decreased by CB addition, and the introduction of Ag nanoparticles promoted an interesting improvement of the flexural resistance. CB resulted to be more effective than NF in decreasing the electrical resistance of the materials down to 10 3 !·cm. Therefore, a rapid heating of the CB-filled samples upon voltage application was observed, while Ag nanoparticles allowed a stabilization of the temperature for elevated voltage application times.

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“…Pequenas quantidades de micro-ou nanocarga, são suficientes para agregar ao polímero uma melhora expressiva em suas propriedades, reduzindo o custo e o peso dos artigos acabados em comparação aos compósitos convencionais [10] . Membranas poliméricas densas têm sido extensivamente estudadas para o emprego em separação de gases, incluindo: o enriquecimento de nitrogênio e de oxigênio; a recuperação de hidrogênio; a remoção de gases ácidos (CO 2 , H 2 S) do gás natural e de voláteis orgânicos; a desidratação de ar e do gás natural, além de outras aplicações, nas áreas química, têxtil, biomédica, petroquímica, farmacêutica e alimentícia [11][12][13][14][15][16][17][18][19][20] . Os poliuretanos (PU) são materiais que têm sido investigados na utilização em membranas densas permeáveis a gases devido à possibilidade de adequação de suas propriedades de transporte através da variação da microestrutura do polímero [15,[21][22][23][24][25][26] .…”

Section: -Avaliação Das Propriedades De Barreira De Membranas Obtidasunclassified

Avaliação das Propriedades de Barreira de Membranas Obtidas a partir de Dispersões Aquosas à Base de Poliuretanos e Argila

Barboza¹,

Delpech²,

Garcia³

et al. 2014

Polímeros

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Resumo: Formulações de aplicação não-poluente à base de poliuretanos em dispersão aquosa (WPUs), com adição de argila montmorilonita hidrofílica (CWPUs), foram sintetizadas. A permeabilidade ao dióxido de carbono (CO 2 ) de membranas densas obtidas a partir do espalhamento das dispersões foi avaliada. Os reagentes empregados na síntese dos materiais foram: poli(glicol proplilênico) (PPG), copolímero em bloco à base de segmentos de poli(glicol etilênico) e poli(glicol propilênico) (EG-b-PG), ácido dimetilolpropiônico (DMPA), diisocianato de isoforona (IPDI) e etilenodiamina (EDA), como extensor de cadeia, levando à formação de ligações de ureia. Diferentes formulações foram obtidas variando-se a proporção de segmentos à base de poli(glicol etilênico) (PEG) e o teor de argila (0,5 e 1 %). As dispersões foram avaliadas em termos de teor de sólidos e viscosidade aparente. As membranas foram caracterizadas por espectrometria na região do infravermelho (FTIR) e permeabilidade ao dióxido de carbono (CO 2 ). A influência nas propriedades de barreira, conferida pela presença da argila e do copolímero em bloco, foi verificada por ensaios de permeabilidade. A permeabilidade ao CO 2 aumentou com o aumento no teor segmentos de PEG e diminuiu com a inserção da argila, uma vez que esta é impermeável a gases, formando caminhos preferenciais na matriz polimérica que retardam a difusão das moléculas de gás. Palavras-chave: Poliuretanos, dispersões aquosas, argila, montmorilonita, membranas, permeabilidade a gases, propriedades de barreira. Evaluation of Carbon Dioxide Gas Barrier Properties of Membranes Obtained from Aqueous Dispersions Based on Polyurethane and ClayAbstract: Non-polluting aqueous polyurethane-based dispersions were synthesized in the presence and absence of montmorillonite hydrophilic clay (WPUs and CWPUs, respectively). The permeability of carbon dioxide (CO 2 ) through dense membranes obtained from the dispersions was evaluated. The reagents used in the synthesis of the materials were: poly(propylene glycol) (PPG), block copolymer of poly(ethylene glycol) and poly(propylene glycol) (EG-b-PG), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and ethylene diamine (EDA) as chain extender, leading to the formation of urea linkages. The proportion of poly(ethylene glycol) (PEG) segments and clay content (0.5 and 1%) was varied in the formulations. The dispersions were evaluated in terms of solids content and apparent viscosity. The membranes were characterized by infrared spectrometry (FTIR) and permeability to carbon dioxide (CO 2 ). The influence on the gas barrier properties, imparted by different contents of PEG segments in polyurethane chains, and by the clay in the formulations was verified. The permeability of CO 2 increased with increasing amounts of PEG segments and decreased with the insertion of clay, since the latter is impermeable to gas and forms, in the polymeric matrix, tortuous pathways that retard gas diffusion.

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Free volume and water vapor permeability of dense segmented polyurethane membrane

Cited by 111 publications

References 20 publications

Polyurethane: A Shape Memory Polymer (SMP)

Polyurethane: A Shape Memory Polymer (SMP)

Electrically conductive epoxy nanocomposites containing carbonaceous fillers and in-situ generated silver nanoparticles

Avaliação das Propriedades de Barreira de Membranas Obtidas a partir de Dispersões Aquosas à Base de Poliuretanos e Argila

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