Neural network applications in polymerization processes

Neural networks currently play a major role in the modeling, control and optimization of polymerization processes and in polymer resin development. This paper is a brief tutorial on simple and practical procedures that can help in selecting and training neural networks and addresses complex cases where the application of neural networks has been successful in the field of polymerization.401418Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Water-based polyurethane dispersions: chemistry, technology and applications

Over the past few decades, polyurethane-polyurea aqueous dispersions (PUDs) have developed a solid reputation for high performance applications, particularly in the field of adhesives and coatings. PUDs are mostly environmentally compatible products; they are totally devoid or contain only low amounts of volatile organic compounds (VOC). This is an important feature in view of the present environmental policies where governments and internal agencies are placing emphasis on developing sustainable processes, improving work conditions and reducing emissions of toxic and polluting substances into the atmosphere. In the past years, our research group has been involved in the development of polyurethane-polyurea aqueous dispersions for two main applications (footwear and indirect food contact). With this work we intend to review this theme and describe some of the achieved developments. Characterization of commercial dispersions will be presented and examples of synthesis will be described, following a modified pre-polymer process developed in our group

Aroma encapsulation for antibacterial and eco-friendly textile finishing

Encapsulation imparts new properties and added value to conventional fabrics. Most of the commercially available microcapsules for textile applications are made of melamine-formaldehyde, urea-formaldehyde or phenolformaldehyde resins, which have significant negative health and environmental effects. Recently, there has been a growing interest in the replacement of these resins with safe and environmentally benign materials. The process of fixing the microcapsules onto textile substrates is critical in ensuring their durability and effectiveness. The commonly known industrial methods used for this involve the use of two main groups of binders; polymeric resins, and polyfunctional crosslinking agents. Polymeric resins are reported to partially inhibit the release of fragrance from the microcapsules. The chemical cross-linkers are subdivided into formaldehyde based, e.g., formaldehyde and glutaraldehyde, and non-formaldehyde based, such as polycarboxylic acids. This work aimed at conferring fragrant and antibacterial properties to cotton fabrics employing new methodologies utilizing non-toxic and environmentally friendly materials.info:eu-repo/semantics/publishedVersio

Microencapsulation of limonen oil for textile application

The production of polyurethane-urea microcapsules using the interfacial polymerization technology was performed. Microcapsules were produced in a basic IKA® Miniplant laboratory reactor, in order to produce microcapsules with controlled parameters. In this formulation, limonene, a fragrant chemical characteristic of the lemon oil - was microencapsulated, because lemon oil is the most used oil in perfumery. It resulted in microcapsules with bimodal distribution and average size equal to 10µm. The characterisation of the microcapsules includes particle size distribution, optical microscopy and scanning electron microscopy. Using scanning electron microscopy it is visible the presence of well defined microcapsules on the woven.Project SCENTFASHION, contract ADI/2004/M2.3/0015POCI funded by Agência de Inovação(AdI) in the framework of POCI 2010-Medida 2.3-IDEIA

Desenvolvimento de um processo de microencapsulação baseado em quitosano para proteção do α-tocoferol

Este trabalho foi realizado no âmbito da unidade curricular de Projeto da Licenciatura em Engenharia Biomédica do Instituto Politécnico de Bragança. Teve como principal objetivo desenvolver um processo de microencapsulação para proteção do α-tocoferol, a principal forma da vitamina E. O α-tocoferol é um antioxidante que possui um papel importante na proteção do organismo contra certos tipos de cancro e do envelhecimento da pele. Contudo, apresenta instabilidade à temperatura, oxigénio e luz, sendo importante a sua microencapsulação para garantir a sua proteção. Os estudos preliminares levados a cabo no âmbito da unidade curricular supramencionada consideram a utilização de duas matrizes poliméricas (quitosano e alginato), optando-se neste trabalho por apresentar os resultados obtidos com o quitosano e na perspetiva do desenvolvimento do processo de microencapsulação. Numa última etapa, o comportamento das microesferas produzidas foi testado para diferentes condições de pH

Microencapsulação de um extrato de rosa micrantha para utilização na área alimentar

Os extratos de plantas são fontes abundantes de compostos fenólicos com propriedades antioxidantes reconhecidas. Dados os benefícios que aportam para a saúde humana, estes assumem grande relevância na indústria alimentar, nomeadamente no desenvolvimento de alimentos funcionais. No entanto, estes compostos de reconhecida instabilidade, podem sofrer alterações durante o processamento dos alimentos onde são incorporados e processos metabólicos. Neste contexto, a microencapsulação possibilita a proteção destes antioxidantes naturais, permitindo ainda a sua libertação controlada1. O presente trabalho teve como objetivo avaliar as propriedades antioxidantes do extrato hidroalcoólico de Rosa micrantha Borrer ex Sm e do seu flavonoide maioritário, a catequina, na sua forma livre e microencapsulada quando incorporados num iogurte natural. Para o efeito foram preparadas microesferas de alginato utilizando uma técnica de microencapsulação por spray seguida de coagulação. O processo foi otimizado numa primeira fase utilizando a catequina como composto modelo, sendo posteriormente aplicada ao extrato de R. micrantha. Quando comparada com o seu homólogo microencapsulado, a incorporação direta do extrato de R. micrantha conduziu a produtos com atividade antioxidante inicial superior (avaliação para t=0). No entanto, os iogurtes aditivados com o microencapsulado apresentaram uma capacidade de manutenção da atividade antioxidante superior (avaliação para t=3 dias). No que respeita à catequina, esta apresentou uma grande instabilidade, sendo que a sua microencapsulação pelo processo utilizado não conduziu a melhorias significativas da preservação da sua atividade antioxidante com o tempo e quando incorporada no iogurte.FCT pelo apoio financeiro ao CIMO (projeto estratégico PEstOE/AGR/UI0690/2011), LSRE (projeto estratégico PEst-C/EQB/LA0020/2011) e Lillian Barros (contrato Compromisso para a Ciência 2008); agradecem também à Professora Doutora Ana Maria Carvalho (CIMO-ESA/IPB) pela colheita e identificação de R. micrantha

Application of spray-coagulation method to microencapsulate catechin having in view cosmetic, pharmaceutical or nutraceutical areas

Catechin is a polyphenolic compound of the flavonoid family and a product of the secondary metabolism of various plants [1 ]. Antioxidant and chelating properties are attributed to catechin, as well as to other flavonoids, due to their aromatic hydroxyl groups. The presence of these bioactive components in diets rich in vegetables offers a protective effect in human health, including prevention of cardiovascular disorders and certain cancers, and in the ageing process itself. When ingested, catechin undergoes a process of metabolism that changes its structure affecting the antioxidant properties [2]. Microencapsulation can be used to overcome this problem offering protection by means of a cover material and enabling its controlled release over time or selectively to an intended target [3]. In this study catechin was microencapsulated in an alginate matrix by using a spray-coagulation technique. Briefly, a sodium alginate solution (4%, w/v) containing catechin was prepared under stirring at ambient temperature by using a ratio catechin:alginate of 25:400 (w/w). The solution was atomized in a Nisco Var J30 unit and microspheres consolidated upon contact with a solution of CaCI2 (4%, w/v), recovered by decantation and washed with deionized water. In order to control the process, microspheres formation was followed by optical microscopy (OM), and catechin loss evaluated after consolidation/washing steps. In conclusion, alginate-based microspheres loaded with catechin were efficiently produced. The obtained microspheres have a medium particle size comprised between 73 and 341 1-Jm and encapsulation efficiency was estimated as 87%. Overall, catechin was microencapsulated with success, and can be incorporated in different formulations in order to apply its antioxidant properties in cosmetic, pharmaceutical or nutraceutical areas. The work will proceed by evaluating the protective effect of the used microencapsulation process on catechin antioxidant properties.FCT for financial support to CIMO (strategic project PEstOE/ AGR/UI0690/2011) and to LSRE (strategic project PEst-C/EQB/LA0020/2011 }. L. Barros also thanks to FCT, POPH-QREN and FSE for her grant (SFRH/BPD/4609/2008

Application of spray-coagulation method to microencapsulate catechin having in view cosmetic, pharmaceutical or nutraceutical areas

Catechin is a polyphenolic compound of the flavonoid family and a product of the secondary metabolism of various plants [1 ]. Antioxidant and chelating properties are attributed to catechin, as well as to other flavonoids, due to their aromatic hydroxyl groups. The presence of these bioactive components in diets rich in vegetables offers a protective effect in human health, including prevention of cardiovascular disorders and certain cancers, and in the ageing process itself. When ingested, catechin undergoes a process of metabolism that changes its structure affecting the antioxidant properties [2]. Microencapsulation can be used to overcome this problem offering protection by means of a cover material and enabling its controlled release over time or selectively to an intended target [3]. In this study catechin was microencapsulated in an alginate matrix by using a spray-coagulation technique. Briefly, a sodium alginate solution (4%, w/v) containing catechin was prepared under stirring at ambient temperature by using a ratio catechin:alginate of 25:400 (w/w). The solution was atomized in a Nisco Var J30 unit and microspheres consolidated upon contact with a solution of CaCI2 (4%, w/v), recovered by decantation and washed with deionized water. In order to control the process, microspheres formation was followed by optical microscopy (OM), and catechin loss evaluated after consolidation/washing steps. In conclusion, alginate-based microspheres loaded with catechin were efficiently produced. The obtained microspheres have a medium particle size comprised between 73 and 341 1-Jm and encapsulation efficiency was estimated as 87%. Overall, catechin was microencapsulated with success, and can be incorporated in different formulations in order to apply its antioxidant properties in cosmetic, pharmaceutical or nutraceutical areas. The work will proceed by evaluating the protective effect of the used microencapsulation process on catechin antioxidant properties.FCT for financial support to CIMO (strategic project PEstOE/ AGR/UI0690/2011) and to LSRE (strategic project PEst-C/EQB/LA0020/2011 }. L. Barros also thanks to FCT, POPH-QREN and FSE for her grant (SFRH/BPD/4609/2008

Chitosan microparticles loaded with essential oils having in view leather applications

Chitosan is a biopolymer attracting considerable attention for diverse applications due to its unique properties like biodegradability, biocompability, non-toxicity and antimicrobial activity. It is obtained by the partial N-deacetylation of chitin, which is the second most abundant polysaccharide in nature, next to cellulose. Chitosan is a viable base material for functional coatings development, namely due to its antimicrobial activity. This characteristic is especially useful for footwear applications that constitute products prone to microbial attack. In this context, developing antimicrobial coatings to be used in footwear components in direct contact with the feet are of great interest, both at industrial level (reducing possibility of material deterioration and quality loss), as well as, from the consumer’s point of view (decrease of skin infections and minor unpleasant odours). Following our previous work, where leather impregnation with chitosan was studied at laboratorial level with quite promising results, and having in view the final application (footwear leather components), where the antimicrobial effect must need to be enhanced, we have developed the idea of microencapsulate different essential oils, with recognized antimicrobial activity like lemon, oregano, eucalyptus and pine. These chitosan-based microparticles, loaded with the chosen essential oil are intended to be applied conjunctly with the chitosan coating process previously studied. Microencapsulation will ensure that the loaded core material will be progressively released, reinforcing the antimicrobial durability and effectiveness of the final product.COMPETE, QREN and EU within the project QREN-ADI-1585-ADVANCEDSHO

Chitosan-based leather functional coatings with improved antimicrobial properties

Among the interesting biological activities that have been ascribed to chitosan, the antimicrobial activity is probably the one that generates the higher number of applications. Developing antimicrobial coatings for footwear components to be used in direct contact with the feet is of great interest; both at industrial level (reducing the possibility of material deterioration and quality loss) and from the consumer’s point of view (decreasing skin infections and minimizing unpleasant odours). One weakness of this application is addressed to the durability and efficiency of the product antimicrobial activity, since it is directly associated with the availability of the positively charged R–NH3 + groups that are depleted during use