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Evaluating the irritant factors of silicone and hydrocolloid skin contact adhesives using trans-epidermal water loss, protein stripping, erythema, and ease of removalDyson, Edward, Sikkink, Stephen, Nocita, Davide, Twigg, Peter C., Westgate, Gillian E., Swift, Thomas 01 January 2024 (has links)
Yes / A composite silicone skin adhesive material was designed to improve its water vapor permeability to offer advantages to wearer comfort compared to existing skin adhesive dressings available (including perforated silicone and hydrocolloid products). The chemical and mechanical properties of this novel dressing were analyzed to show that it has a high creep compliance, offering anisotropic elasticity that is likely to place less stress on the skin. A participant study was carried out in which 31 participants wore a novel silicone skin adhesive (Sil2) and a hydrocolloid competitor and were monitored for physiological response to the dressings. Trans-epidermal water loss (TEWL) was measured pre- and postwear to determine impairment of skin barrier function. Sil2 exhibited a higher vapor permeability than the hydrocolloid dressings during wear. Peel strength measurements and dye counter staining of the removed dressings showed that the hydrocolloid had a higher adhesion to the participants’ skin, resulting in a greater removal of proteins from the stratum corneum and a higher pain rating from participants on removal. Once the dressings were removed, TEWL of the participants skin beneath the Sil2 was close to normal in comparison to the hydrocolloid dressings that showed an increase in skin TEWL, indicating that the skin had been highly occluded. Analysis of the skin immediately after removal showed a higher incidence of erythema following application of hydrocolloid dressings (>60%) compared to Sil2, ( / T.S. received partial funding to study skin adhesive materials from a Medical Research Council Confidence in Concept grant obtained by John Bridgeman at the University of Bradford (MC_PC_19030). Initial formulation and characterization work benchmarking the Sil2 material was funded in part by Trio Healthcare Ltd., who have had no role in the analysis or interpretation of the data presented. All data was obtained independently by staff at the University of Bradford. We also wish to thank the Royal Society of Chemistry for funding Edward Dyson’s position as a research technician via a Research Enablement Grant (E21-8346952505).
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Mechanical, optical, and water vapor barrier properties of canola protein isolate-based edible films2013 June 1900 (has links)
Biodegradable edible films are both economically and environmentally important to the food industry as packaging and coating materials, as the industry seeks to find a replacement to traditional petroleum-derived synthetic polymers. The overall goal of this thesis was to design a canola protein isolate (CPI)-based biodegradable and edible film that provides excellent mechanical, optical and water vapor barrier properties. A better understanding of the potential of CPI for use as a film-forming ingredient could lead to enhanced utilization and value of the protein for food and non-food applications.
In study one, the mechanical, optical and water vapor barrier properties of CPI-based films were investigated as a function of protein (5.0% and 7.5% w/w) and glycerol (30%, 35%, 40%, 45%, and 50% w/w of CPI) concentrations. Overall, as the glycerol concentration increased for the 5.0% and 7.5% CPI-based films, mechanical strength and flexibility decreased and increased, respectively. Film strength was also found to increase at the higher protein concentration; however corresponding changes to film flexibility differed depending on the testing method used. For instance, puncture deformation testing indicated that film flexibility was reduced as the CPI concentration was raised, whereas tensile elongation testing indicated no change in extensibility between the two CPI concentrations. Film transparency was found to increase with increasing levels of glycerol and decreasing levels of CPI, whereas water vapor permeability was found to increase with increasing levels of both glycerol and protein.
In study two, mechanical, optical and vapor barrier properties of CPI-based films were evaluated as a function of plasticizer-type (50% (w/w of CPI), glycerol, sorbitol, polyethylene glycol 400 (PEG-400)) and fixative condition (0% and 1% (w/w of CPI), genipin). CPI films prepared with sorbitol were significantly stronger than films with PEG-400, followed by films with glycerol, whereas the flexibility of CPI-based films with glycerol was higher than films with PEG-400, followed by films with sorbitol. In all cases, films prepared with genipin were stronger and less malleable than un-cross linked films. CPI films with glycerol were more transparent than films with sorbitol, followed by films with PEG-400, and the addition of genipin significantly increased the opacity of CPI films. CPI films prepared with glycerol also showed poorer water vapor barrier property than films with PEG-400, followed by films with sorbitol, however, no differences were observed in the presence and absence of genipin.
In summary, as the plasticizer concentration increased or protein concentration decreased, CPI films became weaker, more flexible and clearer; however their water vapor barrier properties became poorer as both plasticizer and protein concentration increased. Moreover, CPI films with sorbitol and genipin were found to be stronger, less malleable and permeable to moisture than CPI films with or without genipin, and in the presence of glycerol or PEG-400. Overall, CPI could be considered as a potential material for the development of biodegradable edible packaging in the future.
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Effects of soluble soybean polysaccharide as filling agent on the properties of leathersTang, Zhenye, Zhong, Jide, Feng, Xianqing, Zhang, Yafei, Hu, Yadi, Liu, Hui, Liu, Jie, Ferah, Cem Emre, Tang, Keyong 28 June 2019 (has links)
Content:
Soluble soybean polysaccharide (SSPS) is good in emulsification, and stable emulsion may be formed with the addition of SSPS in fatliquoring agents. In this paper, with wet blues as raw materials, after
being retanned and neutralized, fatliquoring and filling up with SSPS were carried out at the same time, with different amounts of SSPS, i.e., 1%, 3%, 5%,7% in weight. The leather samples were dried at room temperature. The effects of SSPS amounts on the thickness, air permeability and water vapor permeability of the crust leather were studied. The tensile properties of the leathers filled by SSPS were analyzed. The results indicated that with increasing the amounts of SSPS, the thickness and the water vapor permeability of the leathers increase, while the air permeability decreases slightly. The maximum stress-strain capacity of leathers decreases with increasing the SSPS amount. At the SSPS amount of 3%, the leather is good in softness, as well as in physical and mechanical properties.
Take-Away:
1.SSPS from soybean dregs is an acidic polysaccharide, which is rich in raw materials and low in cost.
2.Leathers filled with SSPS have good performance.
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IncorporaÃÃo de Ãleo essencial de manjericÃo em filmes biodegradÃveis à base de galactomanana e Ãleo de canola / Essential oil of basil incorporation into biodegradable films galactomannan base and canola oilRosueti DiÃgenes de Oliveira Filho 12 August 2015 (has links)
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Embalagens biodegradÃveis sÃo coberturas utilizadas em alimentos na forma de filmes ou revestimentos, formadas por macromolÃculas tanto de origem vegetal como de origem animal, que garantem propriedades de barreira e podem servir como veÃculo para compostos antimicrobianos. Os polissacarÃdeos de reserva de parede celular, principalmente as hemiceluloses como as galactomananas, vÃm sendo extensamente usadas como matrizes polimÃricas de filmes biodegradÃveis. O objetivo deste trabalho foi avaliar a incorporaÃÃo de Ãleo essencial de manjericÃo (OEM) (Ocimum basilicum) em filmes biodegradÃveis à base de galactomanana endospÃrmica de sementes de flamboyant (Delonix regia) e Ãleo canola (OC) (Brassica napus L.). A Galactomanana (Gal) foi isolada por extraÃÃo aquosa, seguida por precipitaÃÃo em etanol. O rendimento determinado foi de 12,0%, com alto grau de pureza apresentado pelo baixo teor de nitrogÃnio expresso em proteÃna (0,67%). A Gal apresentou viscosidade intrÃnseca mÃdia de 3,79 dL/g e massa molar estimada de 1,04x106 g/mol. Os espectros de infravermelho por transformada de Fourier (FTIR) e ressonÃncia magnÃtica nuclear (RMN) de 1H e 13C foram similares aos encontrados na literatura para outras galactomananas. A composiÃÃo em Ãcidos graxos do OC por cromatografia a gÃs (GC-FID) apresentou teores de Ãcido oleico (62,07%), linoleico (18,91%) e heneicosanÃico (6,61%). Os componentes majoritÃrios do OEM determinados por cromatografia a gÃs acoplado à espectrometria de massas (GC-MS) foram cÃnfora (14,85%) e 1,8-cineol (3,48%). Os filmes foram formulados com Gal 1% (m/v), glicerol 0,5% (m/v) e OC em diferentes concentraÃÃes, 0,25, 0,5 e 0,75% (m/v). Os filmes foram obtidos pelo mÃtodo de evaporaÃÃo de solvente (casting) e caracterizados quanto ao teor de umidade, espessura, permeabilidade ao vapor de Ãgua (PVA), cor e opacidade. O OC promoveu aumento de PVA e diminuiÃÃo do teor de umidade quando comparado ao filme apenas de galactomanana, mas sem diferenÃa significativa entre as concentraÃÃes. O OEM foi testado frente Ãs cepas bacterianas de Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella choleraesuis, Staphylococcus aureus e levedura Candida albicans por microdiluiÃÃo em caldo e apresentou concentraÃÃo inibitÃria mÃnima (CIM) variando entre 2,5 e 5,0 mg/mL e concentraÃÃo bactericida mÃnima (CBM) entre 5,0 e 20,0 mg/mL. A partir do filme com formulaÃÃo de 0,5 % (m/v) de OC incorporou-se OEM em diferentes concentraÃÃes (2,5, 5,0 e 7,5 mg/mL). Os filmes antimicrobianos foram obtidos por casting e discos de 1 cm de diÃmetro foram excisados e testados por mÃtodo de difusÃo em Ãgar e a zona de contato e os halos de inibiÃÃo analisados. S. aureus, E. coli e P. aeruginosa foram sensÃveis ao filme contendo 5,0 mg/mL de OEM apresentando halos de 14, 15 e 16,3 mm, respectivamente. K. pneumoniae foi inibida apenas na zona de contato do filme, enquanto que S. choleraesuis e C. albicans foram resistentes à todas as formulaÃÃes. Contudo, O OC promoveu alteraÃÃes nas propriedades fÃsicas e de barreira dos filmes de galactomanana e OEM quando incorporado ao filme apresentou uma atividade antimicrobiana moderada para potencial aplicaÃÃo como embalagens bioativas. / Biodegradable Packaging are used in foods as films or coatings formed by plant macromolecules such as animal, ensuring barrier properties and can serve as a carrier for antimicrobial compounds. The cell wall polysaccharides reservation, especially hemicelluloses as galactomannans, have been used widely as biodegradable polymer matrices films. The objective of this study was to evaluate the Basil essential oil (BEO) (Ocimum basilicum) incorporation in biodegradable films based on endospermic galactomannan Delonix regia seeds and canola oil (CO) (Brassica napus L.). The galactomannan (Gal) was isolated by aqueous extraction, followed by ethanol precipitation. The yield was 12.0% with high purity presented by low nitrogen content expressed protein (0.67%). The Gal showed an average intrinsic
viscosity of 3.79 dL/g and molecular weight estimated in 1,04x106 g/mol. Infrared spectra by Fourier transform (FTIR) and nuclear magnetic resonance (NMR) 1H and 13C were similar to those found in the literature for other galactomannans. The fatty acid composition of CO by gas chromatography (GC-FID) showed oleic acid (62.07%), linoleic (18.91%) and heneicosanÃico (6.61%) content. The major components of BEO determined by gas chromatography coupled to mass spectrometry (GC-MS) were camphor (14.85%) and 1.8-cineole (3.48%). The films were formulated with galactomannan 1% (w/v), glycerol 0.5% (w/v) and CO at
different concentrations, 0.25, 0.5 and 0.75% (w/v). The films were obtained by the solvent evaporation method (casting) and characterized as the moisture content, thickness, water vapor permeability (WVP), color and opacity. The CO promoted increase of WPV and reduced moisture content when compared to the film based only in galactomannan but no significant difference between concentrations. BEO was tested against the bacterial strains of Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella choleraesuis, Staphylococcus aureus and Candida albicans yeast by broth microdilution and showed minimum inhibitory concentration (MIC) ranging between 2.5 and 5.0 mg/ml and minimum bactericidal concentration (MBC) between 5.0 and 20.0 mg/ml. BEO was incorporated into film formulation with CO 0.5% (w/v) in different concentrations (2.5,
5.0 and 7.5 mg/ml). The antimicrobial films were obtained by casting and disks of 1 cm in diameter were excised and tested by the agar diffusion method and a contact zone and inhibition halos analyzed. S. aureus, E. coli and P. aeruginosa were sensitive to film containing BEO 5.0 mg/ml showed halos of 14, 15 and 16.3 mm, respectively. K. pneumoniae was inhibited only in the contact zone of the film, while
S. choleraesuis and C. albicans were resistant to all formulations. However, the OC promoted changes in physical and barrier properties of the films of with galactomannan. BEO when incorporated into the film showed a moderate antimicrobial activity for potential application as bioactive packaging.
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ANÁLISE DA PERMEABILIDADE DE ARGAMASSAS ESTABILIZADAS SUBMETIDAS A TRATAMENTO SUPERFICIAL COM ADITIVOS CRISTALIZANTES / PERMEABILITY ANALYSIS OF READY-TO-USE MORTARS WITH WATERPROOFING TREATMENTJantsch, Ana Cláudia Akele 27 August 2015 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / Water presence is one of the major causes of pathological manifestations in mortar coatings. Such problem endangers the material durability, and the protection ability of these coatings, thus allowing early degradation of materials and structures. On the other hand, the use of waterproofing treatment promises to solve this issue, creating a barrier to water penetration. However, few non-commercial studies are found on this matter, even rarer are the researches that focus on ready-to-use mortars. Therefore, the present study sought to analyze 36h and 72h ready-to-use mortars produced in the city of Santa Maria with and without the application of crystallizing treatment to evaluate these mortars performance. The methods consisted in evaluating the fresh and hardened characteristics of these materials. At the end of the experiments, it was concluded that the 36h mortar showed superior performance in comparison to the 72h mortar and although the application of crystallizing treatments did not waterproof the mortars, it did contributed to reduce their water absorption, abrasion resistance and improve vapor permeability. / A presença da água é uma das principais causas para o aparecimento e disseminação de manifestações patológicas em revestimentos argamassados. Tal problema põe em risco a capacidade de proteção desses revestimentos e, em consequência, a durabilidade, permitindo assim a degradação precoce de materiais e estruturas. Por outro lado, a utilização de aditivos impermeabilizantes promete solucionar essa questão, criando uma barreira à penetração de água. No entanto, poucos estudos - não comerciais - são encontrados sobre a utilização de agentes cristalizantes em materiais cimentícios, mais raro ainda pesquisas de sua utilização em argamassas comuns ou estabilizadas. Diante disso, a presente pesquisa analisou argamassas estabilizadas de 36h e 72h produzidas em Santa Maria com e sem a adição de tratamentos cristalizantes para verificar seu desempenho. Os métodos empregados consistiram na avaliação das características no estado fresco e endurecido desses materiais. Ao fim da bateria de ensaios, se pode concluir que as argamassas de 36h apresentaram desempenho superior ao das argamassas de 72h e a aplicação dos tratamentos cristalizantes, apesar de não tornarem as argamassas impermeáveis, contribuíram para a redução de absorção de água, a resistência ao desgaste e a permeabilidade ao vapor.
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Mesoporous Hollow SiO2 Spheres Stabilized Pickering Emulsion to Improve Water Vapor Permeability and Water Resistance for Leather Finishing AgentBao, Yan, Zhang, Yuanxia, Ma, Jianzhong 28 June 2019 (has links)
Content:
In order to solve the negative impact of coating on water vapor permeability of leather and overcome the poor water resistance of polyacrylate leather finishing agent, it was proposed that the mesoporous SiO2 spheres with hollow structure instead of traditional surfactant were introduced into polyacrylate by Pickering emulsion polymerization. It was expected to increase the water vapor permeability of
polyacrylate film by increasing the path and shortening the route of water vapor molecules through the film, and improve the water resistance of film by avoiding the use of surfactant.
Hence, stable Pickering emulsion stabilized by mesoporous hollow SiO2 spheres was prepared and its stability was investigated by Turbiscan Lab in this paper. Water vapor permeability, water uptake and
mechanical property of polyacrylate film were also studied. Compared with emulsion stabilized by surfactant, Pickering emulsion indicated excellent stability with lower TSI value of 0.5. Contrasted with
polyacrylate film with SDS, the introduction of mesoporous hollow SiO2 spheres can improve the water vapor permeability of polyacrylate film. Meanwhile, water absorption measurements showed that the
water absorption ratio of the film with mesoporous hollow SiO2 spheres decreased from 112.34 to 40.84%, possessing the ideal ability to water resistance of polyacrylate film. Its film with mesoporous hollow SiO2 spheres also revealed increases of up to 188% in tensile strength and 41.15% in elongation at break. This study can provide a theoretical foundation for designing and synthesizing leather finishing agent with excellent stability, water vapor permeability and water resistance synchronously.
Take-Away:
1. Mesoporous hollow SiO2 spheres stabilized Pickering emulsion exhibits outstanding stability.
2. The introduction of mesoporous hollow SiO2 spheres can improve the water vapor permeability of polyacrylate membrane.
3. Polyacrylate membrane shows excellent water resistance.
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Étude des mécanismes de transferts couplés de chaleur et d’humidité dans les matériaux poreux de construction en régime insaturé / Study of coupled heat and moisture transfer mechanisms in porous building materials in unsaturated regimeBennai, Fares 28 June 2017 (has links)
Le présent travail a pour objectif de comprendre l’influence des paramètres géométriques des éco-matériaux d’enveloppe, tels que le béton de chanvre, sur les mécanismes de transferts couplés de chaleur, d'air et d’humidité afin de prédire le comportement du bâtiment dans le but de le piloter et de l’améliorer dans sa durabilité. Pour cela, une approche multi-échelle est mise en place. Elle consiste à maîtriser les phénomènes physiques dominants et leurs interactions à l’échelle microscopique. S’ensuit, une modélisation à double échelle, microscopique–macroscopique, des transferts couplés de chaleur, d’air et d’humidité qui prend en compte les propriétés intrinsèques et la topologie microstructurale du matériau moyennant le recours à la tomographie rayon X conjuguée à la corrélation d’images 2D et 3D. Pour cela, une campagne de caractérisation fine des propriétés physiques et hygrothermiques du béton de chanvre confectionné au laboratoire a été réalisée. Elle s’est focalisée sur l’étude de l’impact du vieillissement, l’état thermique et hydrique du matériau sur ses propriétés intrinsèques. Les résultats montrent une excellente capacité d'isolation thermique et de régulation naturelle d’humidité du béton de chanvre. Puis, une caractérisation microscopique par différentes techniques d’imagerie a été effectuée. Les reconstructions 3D du matériau réel scanné au tomographe aux rayons X à différentes résolutions montrent que le béton de chanvre possède plusieurs échelles de porosité, allant de la microporosité au sein du liant et des chènevottes à la macroporosité inter-particulaire. Le comportement hygro-morphique sous sollicitations hydriques a été ensuite étudié. Les résultats de la corrélation d’image numérique 2D et de la tomographie aux rayons X couplés à la corrélation d’images volumiques, montrent la nature du comportement du béton de chanvre soumis à des hygrométries différentes. En effet, la chènevotte subit des déformations plus importantes que le liant, causant ainsi des modifications de la microstructure du matériau. Sur le volet de la modélisation, moyennant la technique d’homogénéisation périodique un modèle des transferts couplés de chaleur, d’air et d’humidité dans les matériaux poreux de construction a été développé. Les tenseurs de diffusion et de conductivité thermique homogénéisés ont été calculés numériquement. Ensuite, une confrontation entre les résultats du calcul des coefficients de diffusion macroscopique et ceux expérimentaux obtenus au LaSIE a été réalisée. Elle met en évidence la qualité de la prédiction. De plus, la conductivité thermique de la phase solide a été ainsi déduite. Les résultats obtenus dans le cadre de ce travail de thèse ont mis en exergue l’influence de l’état hydrique et thermique du béton de chanvre sur ces propriétés intrinsèques, et sa microstructure très hétérogène. Ils ont révélé aussi les limites des approches phénoménologiques basées sur l’établissement des bilans de masse, de quantité de mouvement et d’énergie. / The aim of this work is to understand the influence of the geometric parameters of envelope eco-materials, such as hemp concrete, on the mechanisms of coupled heat, air and moisture transfers, in order to predict behavior of the building to control and improving it in its durability. For this a multi-scale approach is implemented. It consists of mastering the dominant physical phenomena and their interactions on the microscopic scale. Followed by a dual-scale modeling, microscopic-macroscopic, of coupled heat, air and moisture transfers that takes into account the intrinsic properties and microstructural topology of the material using X-ray tomography combined with the correlation of 2D and 3D images. A characterization campaign of physical and hydrothermal properties of the hemp concrete manufactured in the laboratory was carried. It focused on studying the impact of aging, thermal and hydric state of the material on these intrinsic properties. The results show an excellent thermal insulation and natural moisture regulation capacity of hemp concrete. Then, a microscopic characterization by different imaging techniques was performed. The 3D reconstructions of the real material scanned with X-ray tomography at different resolutions show that hemp concrete has several scales of porosity, ranging from micro-porosity within the binder and hemp shiv to the inter-particle macro-porosity. The hydromorphic behavior under hydric solicitations was studied. The results of the 2D digital image correlation and X-ray tomography coupled with the volumetric image correlation show the nature of the behavior of hemp concrete subjected to different relative humidities. In fact, the hemp shiv undergoes greater deformations than the binder, thus causing changes in the microstructure of the material. On the modeling part, a model of coupled heat, air and moisture transfer in porous building materials was developed using the periodic homogenization technique. The homogenized tensors of diffusion and thermal conductivity were determined numerically. Then, a confrontation between the results of the calculation of the macroscopic diffusion coefficients and the experimental results obtained at the LaSIE was carried out. It highlights the quality of the prediction. In addition, the thermal conductivity of the solid phase was thus deduced. The results obtained in the framework of this PhD thesis have highlighted the influence of the hydric and thermal state of the hemp concrete on these intrinsic properties and its very heterogeneous microstructure. They also revealed the limitations of phenomenological approaches based on the establishment of the balances of mass, amount of motion and energy
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Utilisation du caséinate de sodium pour la fabrication de films actifs pour l’emballage alimentaire : étude des propriétés barrières aux gaz, de l’activité antimicrobienne et de la biodégradabilité / Fabrication of sodium caseinate edible films for active food packaging : study of gas barrier properties, antimicrobial activity and biodegradabilityColak, Basak Yilin 14 November 2014 (has links)
La mondialisation des marchés, les changements d’habitudes de consommation et les préoccupations croissantes concernant la sécurité alimentaire et l’environnement sont des éléments moteurs pour le développement des films d’emballage comestibles/biodégradables antimicrobiens. Une utilisation en masse de ce type de film est dépendante principalement des verrous technologiques car le mode de fabrication actuellement utilisé pour ce genre de film consiste à utiliser un procédé (voie solvant) qui n’est pas toujours adapté à une production importante et continue. L’étude présentée ici permet de montrer la possibilité d’obtenir des films comestibles antimicrobiens à partir de caséinate de sodium en utilisant les procédés traditionnels de la plasturgie : extrusion bi-vis et extrusion-gonflage. Grâce aux optimisations des paramètres d’élaboration tels que la température de transformation, le taux de cisaillement et le taux de plastifiant, les matériaux contenant un agent actif naturel : le lysozyme, la nisine ou la natamycine ont gardé en partie leurs activités antimicrobiennes. Par des caractérisations mécaniques et physico-chimiques des films thermoplastiques, il a été démontré que ces films ont des propriétés mécaniques et barrières similaires à ceux fabriqués par voie solvant. Ces propriétés dépendent principalement du taux de plastifiant. Ainsi, il est possible de fabriquer des films comestibles antimicrobiens de caséinate de sodium avec de bonnes propriétés mécaniques et barrières qui ne sont pas affectées par la transformation thermomécanique et qui peuvent être adaptées en fonctions des applications en variant le taux de plastifiant / Because food market becomes international, consumers are changing their habits and they are more concerned about food security and environmental issues, there are driving forces for the development of edible/biodegradable antimicrobial packaging films. However, fabrication process (solution-casting) of these kinds of films isn’t always suitable for a continuous industrial big production. The present study demonstrates the suitability of sodium caseinate based edible antimicrobial films to be fabricated by some conventional plastic transformation processes: twinscrew extrusion and blown-film extrusion. Thanks to the optimizations of elaboration parameters such as extrusion temperature, shear and plasticizer ratio, the materials incorporated with one of the following active agents: lysozyme, nisin or natamycin, partially kept their antimicrobial activity. Physical-chemical film characterization of films emphasized that the type of transformation process doesn’t have any influence on tensile or gas barrier properties. These properties are mainly affected by plasticizer type and content. Thus, sodium caseinate based edible antimicrobial films can be produced successfully by thermo-mechanical processes without losing good mechanical and gas barrier properties
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Investigation of film forming properties of β-chitosan from jumbo squid pens (Dosidicus gigas) and improvement of water solubility of β-chitosan / Investigation of film forming properties of beta-chitosan from jumbo squid pens (Dosidicus gigas) and improvement of water solubility of beta-chitosanChen, Jeremy L. 27 April 2012 (has links)
The objectives of this project were to investigate the critical factors impacting the physicochemical and antibacterial properties of β-chitosan based films derived from jumbo squid (Dosidicus gigas) pens, and to evaluate the feasibility of improving water solubility of β-chitosan through Maillard reaction. The studies examined the effect of molecular weight (1,815 and 366 kDa), acid (formic, acetic, propionic, and lactic acid), and plasticizer (glycerol and sorbitol) on the film properties, as well as reducing sugar (fructose and glucosamine) and heat treatment (high temperature short time (HTST), low temperature long time (LTLT)) on water solubility of chitosan. Results on β-chitosan were compared with α-chitosan in both studies.
Tensile strength (TS) and elongation (EL) of β-chitosan films were influenced by molecular weight (Mw), acid and plasticizer types (P < 0.05). High molecular weight (Hw) β-chitosan films had an overall TS of 44 MPa, 53% higher than that of low
molecular weight (Lw) β-chitosan films (29 MPa) across all acid types used. The mean TS of β-chitosan acetate and propionate films (43 and 39 MPa) were higher (P < 0.05) than that of β-chitosan formate and lactate films (34 and 29 MPa). Films incorporated with plasticizer (32 MPa) had lower TS than those without plasticizer (48 MPa). Mean EL of Hw β-chitosan films was 10% versus approximately 4% in Lw β-chitosan films. Formate and acetate films had higher EL than that of propionate film. Glycerol and sorbitol increased (P < 0.001) EL 151% and 106% compared with the films without plasticizer, respectively. Water vapor permeability (WVP) of the films was affected by acid and plasticizer. Formate films (34 g mm/m² d KPa) had higher WVP than other acid films. Adding plasticizer increased (11% to 31%) WVP of propionate films except the Lw β-chitosan propionate film with sorbitol. The antibacterial activity of Lw β-chitosan and α-chitosan films delayed (P < 0.05) the proliferation of E. coli, where lactate films showed the strongest effect. The growth of L. innocua at 24 h was completely (P < 0.05) inhibited by chitosan films except Hw β-chitosan acetate film.
A soft and cotton-like water soluble chitosan with mesopores was acquired after freeze-drying the Maillard reacted chitosan-sugar solution. The yield of β-chitosan-derivatives (8.48%) was 1.21 times higher than that of α-chitosan products (7.00%) (P < 0.01). Heat treatment only affected the yield of chitosan-glucosamine derivatives. Sugar type did not indicate any impact on the yield of the chitosan-derivative products in general (P > 0.05). The solubility was affected by sugar type (P < 0.01) only occurred in the β-chitosan products prepared with LTLT (P<0.05), where β-chitosan-fructose derivatives (9.56 g/L) had higher solubility than the glucosamine (5.19 g/L).LTLT
treatment had given all chitosan-derivatives a higher solubility (8.44 g/L) than HTST (3.83 g/L) did (P<0.001).
The results from this study demonstrated the feasibility of creating β-chitosan based film from jumbo squid pens with similar mechanical, water barrier and antibacterial properties compare to α-chitosan films as a food wrap and controlled the properties with several important factors, and developing water soluble chitosan through Maillard reaction that possess the potential as functional substance in a wider range of applications. / Graduation date: 2012
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Novel gas-separation membranes for intensified catalytic reactorsEscorihuela Roca, Sara 20 May 2019 (has links)
[ES] La presente tesis doctoral se centra en el desarrollo de nuevas membranas de separación de gases, así como su empleo in-situ en reactores catalíticos de membrana para la intensificación de procesos. Para este propósito, se han sintetizado varios materiales, como polímeros para la fabricación de membranas, catalizadores tanto para la metanación del CO2 como para la reacción de síntesis de Fischer-Tropsch, y diversas partículas inorgánicas nanométricas para su uso en membranas de matriz mixta. En lo referente a la fabricación de las membranas, la tesis aborda principalmente dos tipos: orgánicas e inorgánicas. Con respecto a las membranas orgánicas, se han considerado diferentes materiales poliméricos, tanto para la capa selectiva de la membrana, así como soporte de la misma. Se ha trabajado con poliimidas, puesto que son materiales con temperaturas de transición vítrea muy alta, para su posterior uso en reacciones industriales que tienen lugar entre 250-300 ºC. Para conseguir membranas muy permeables, manteniendo una buena selectividad, es necesario obtener capas selectivas de menos de una micra. Usando como material de soporte otro tipo de polímero, no es necesario estudiar la compatibilidad entre ellos, siendo menos compleja la obtención de capas finas. En cambio, si el soporte es de tipo inorgánico, un exhaustivo estudio de la relación entre la concentración y la viscosidad de la solución polimérica es altamente necesario. Diversas partículas inorgánicas nanométricas se estudiaron para favorecer la permeación de agua a través de los materiales poliméricos. En segundo lugar, en cuanto a membranas inorgánicas, se realizó la funcionalización de una membrana de paladio para favorecer la permeación de hidrógeno y evitar así la contaminación por monóxido de carbono. El motivo por el cual se dopó con otro metal la capa selectiva de la membrana metálica fue para poder emplearla en un reactor de Fischer-Tropsch. Con relación al diseño y fabricación de los reactores, durante esta tesis, se desarrolló el prototipo de un microreactor para la metanación de CO2, donde una membrana polimérica de capa fina selectiva al agua se integró para evitar la desactivación del catalizador, y a su vez desplazar el equilibrio y aumentar la conversión de CO2. Por otro lado, se rediseñó un reactor de Fischer-Tropsch para poder introducir una membrana metálica selectiva a hidrogeno y poder inyectarlo de manera controlada. De esta manera, y siguiendo estudios previos, el objetivo fue mejorar la selectividad a los productos deseados mediante el hidrocraqueo y la hidroisomerización de olefinas y parafinas con la ayuda de la alta presión parcial de hidrógeno. / [CAT] La present tesi doctoral es centra en el desenvolupament de noves membranes de separació de gasos, així com el seu ús in-situ en reactors catalítics de membrana per a la intensificació de processos. Per a aquest propòsit, s'han sintetitzat diversos materials, com a polímers per a la fabricació de membranes, catalitzadors tant per a la metanació del CO2 com per a la reacció de síntesi de Fischer-Tropsch, i diverses partícules inorgàniques nanomètriques per al seu ús en membranes de matriu mixta. Referent a la fabricació de les membranes, la tesi aborda principalment dos tipus: orgàniques i inorgàniques. Respecte a les membranes orgàniques, diferents materials polimèrics s'ha considerat com a candidats prometedors, tant per a la capa selectiva de la membrana, així com com a suport d'aquesta. S'ha treballat amb poliimides, ja que són materials amb temperatures de transició vítria molt alta, per al seu posterior ús en reaccions industrials que tenen lloc entre 250-300 °C. Per a aconseguir membranes molt permeables, mantenint una bona selectivitat, és necessari obtindre capes selectives de menys d'una micra. Emprant com a material de suport altre tipus de polímer, no és necessari estudiar la compatibilitat entre ells, sent menys complexa l'obtenció de capes fines. En canvi, si el suport és de tipus inorgànic, un exhaustiu estudi de la relació entre la concentració i la viscositat de la solució polimèrica és altament necessari. Diverses partícules inorgàniques nanomètriques es van estudiar per a afavorir la permeació d'aigua a través dels materials polimèrics. En segon lloc, quant a membranes inorgàniques, es va realitzar la funcionalització d'una membrana de pal¿ladi per a afavorir la permeació d'hidrogen i evitar la contaminació per monòxid de carboni. El motiu pel qual es va dopar amb un altre metall la capa selectiva de la membrana metàl¿lica va ser per a poder emprar-la en un reactor de Fischer-Tropsch. En relació amb el disseny i fabricació dels reactors, durant aquesta tesi, es va desenvolupar el prototip d'un microreactor per a la metanació de CO2, on una membrana polimèrica de capa fina selectiva a l'aigua es va integrar per a així evitar la desactivació del catalitzador i al seu torn desplaçar l'equilibri i augmentar la conversió de CO2. D'altra banda, un reactor de Fischer-Tropsch va ser redissenyat per a poder introduir una membrana metàl¿lica selectiva a l'hidrogen i poder injectar-lo de manera controlada. D'aquesta manera, i seguint estudis previs, el objectiu va ser millorar la selectivitat als productes desitjats mitjançant el hidrocraqueix i la hidroisomerització d'olefines i parafines amb l'ajuda de l'alta pressió parcial d'hidrogen. / [EN] The present thesis is focused on the development of new gas-separation membranes, as well as their in-situ integration on catalytic membrane reactors for process intensification. For this purpose, several materials have been synthesized such as polymers for membrane manufacture, catalysts for CO2 methanation and Fischer-Tropsch synthesis reaction, and inorganic materials in form of nanometer-sized particles for their use in mixed matrix membranes. Regarding membranes manufacture, this thesis deals mainly with two types: organic and inorganic. With regards to the organic membranes, different polymeric materials have been considered as promising candidates, both for the selective layer of the membrane, as well as a support thereof. Polyimides have been selected since they are materials with very high glass transition temperatures, in order to be used in industrial reactions which take place at temperatures around 250-300 ºC. To obtain highly permeable membranes, while maintaining a good selectivity, it is necessary to develop selective layers of less than one micron. Using another type of polymer as support material, it is not necessary to study the compatibility between membrane and support. On the other hand, if the support is inorganic, an exhaustive study of the relation between the concentration and the viscosity of the polymer solution is highly necessary. In addition, various inorganic particles were studied to favor the permeation of water through polymeric materials. Secondly, as regards to inorganic membranes, the functionalization of a palladium membrane to favor the permeation of hydrogen and avoid carbon monoxide contamination was carried out. The membrane selective layer was doped with another metal in order to be used in a Fischer-Tropsch reactor. Regarding the design and manufacture of the reactors used during this thesis, a prototype of a microreactor for CO2 methanation was carried out, where a thin-film polymer membrane selective to water was integrated to avoid the deactivation of the catalyst and to displace the equilibrium and increase the CO2 conversion. On the other hand, a Fischer-Tropsch reactor was redesigned to introduce a hydrogen-selective metal membrane and to be able to inject it in a controlled manner. In this way, and following previous studies, the aim is to enhance the selectivity to the target products by hydrocracking and hydroisomerization the olefins and paraffins assisted by the presence of an elevated partial pressure of hydrogen. / I would like to acknowledge the Spanish Government, for funding my research with the Severo Ochoa scholarship. / Escorihuela Roca, S. (2019). Novel gas-separation membranes for intensified catalytic reactors [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/121139 / TESIS
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