Effect of PH on lhe control release o microencapsulated dye in lecithin liposomes

The objective of our work has been the microencapsulation of dyes with lecithin from soybean, with the formation of liposomes, as a substitute for synthetic auxiliaries so as to improve the quality of the effluent. Current scenarios promote the disintegration and leakage of the liposomes, such as, changes in temperature, pH and the use of surfactants. Since dyeing process is a mix of all these parameters, we pretended to study each one separately. Changes in pH at constant temperature induce a release of dye similar with changes in temperature. In acid conditions we found a very fast initial dye release which doesn’t occur in basic conditions. Using carboxyfluorescein, as a pH fluorescence probe, we concluded that the liposome membrane doesn’t protect the liposome interior from changes on the external pH

The application of microcapsules of PCM in flame resistant non-woven materials

The use of organic microcapsules of phase change materials (mPCM) has been gaining ground in technical textiles for temperature regulation and hence a means of keeping the body at a comfortable temperature when wearing impermeable protective clothes. However, for such applications as fire-fighter’s protective clothes, the standards require that all the material composing the material be fire resistant, including the lining made of aramid fibres. Organic PCM such as n-octadecane are the most used in textiles, since they are easily microencapsulated in Melamine-formaldehyde (MF) polymers. Paraffins such as n-octadecane however, are flammable and ignite easily. Even though they are microencapsulated, the microcapsules are porous and at high temperatures the paraffin will vaporize and diffuse through the pores. As the application of mPCM is usually through the use of binder applied on the fibres by padding or coating and binders are thermoplastic and inevitably flammable such applications increase the flammability of the material. Based on a new approach where MF microcapsules of n-octadecane were treated with different flame retardant products, either co-polymerised on the surface or attached by ion-exchange, as was the case with Zinc and Boron, it was possible to make flame-retardant microcapsules of n-octadecane. For application on the aramid non-woven, flame retardant and MF resin were applied instead of binder and the material containing the flame retardant microcapsules was then also resistant for example to the standard flame propagation test EN532

Colored nanoparticles for ecological dyeing of cellulosic fibers

Dyeing cellulosic fibres with reactive dyes wastes great quantities of salt and water. The objective of this work is to dye cellulosic fibers using colored nanoparticles (CNPs) as an alternative to dyeing with reactive dyes. CNPs do not need salt nor soaping after dyeing, consuming less than 50% of water

Diffusion of coloured silica nanoparticles into human hair

A novel method for dyeing human hair fibres using coloured silica nanoparticles of 206 nm has been developed. Diffusion of coloured silica nanoparticles into hair fibres has been investigated; silica nanoparticles do not penetrate at all, or do so only sparingly, into the structure of Caucasian virgin hair. However, coloured silica nanoparticles diffused readily into bleached hair fibres. Scanning electron microscopy showed that coloured silica nanoparticles were present mainly in the outer regions of the hair structure (the inner layers of the cuticle and the outer region of the cortex). It was found that the silica nanoparticles were physically entrapped in the hair fibres and results showed a good shampoo fastness to washing

Sol-gel technology for ecological dyeing cellulosic of fibres

Dyeing cellulosic fibres with reactive dyes wastes great quantities of salt and water. The objective of this work is to dye cellulosic fibers using coloured nanoparticles (CNPs) as an alternative to dyeing with reactive dyes, without salt and with only a short washing-off procedure at the end of dyeing. Samples of cotton were dyed by exhaustion with CNPs at light to medium colours. Washfastness results are given. Complete Washing-off sequence after dyeing was not necessary for the red and yellow colours, only one rinsing. The blue colour needs some washing off since the fastness is lower than for the other colours even though soaping is not necessary, saving energy and time relative to dyeing with reactive dyes

Verbesserungsmöglichkelten von färberischen-und antimikrobiellen eigenschaften auf baumwolle

Comunicação apresentada no 20th IFATCC Congress, Weimer, Germany, 5 - 6 Maio 2005.In the present work, some specific amino compounds were linked to the cotton fabrics on a process that can impart at the same time dyeability and durable antimicrobial properties. The process was monitored on-line in a prototype dyeing system since the addition of cationic agents will influence dye uptake. Different dyeing conditions were tested with direct dyes, with and without salt, until the exhaustion curve was at least equivalent to the standard dyeing curve in the presence of salt

Dyeing of PA6.6 fibers - Effect of solvent and temperature on thermal properties

Dyeing fibers at low temperatures has many advantages such as savings in energy and avoiding alterations to the physical properties of the fibers being dyed or other fibers also present in blends, The problem of low temperature dyeing in synthetic fibers is that it difficults the dye diffusion into the fiber. In the case of polyamide 6.6 microfibers, by using benzyl alcohol as an auxiliary dyeing, it was shown that good diffusion was obtained for the dye exhaustion with metal complex dyes at temperatures more than 30°C below the normal dyeing temperature for the dye exhaustion with metal complex dyes. Using thermal analysis methods these results were shown to be caused by the lowering of the T g of the fiber when in the presence of benzyl alcohol.Fundação para a Ciência e a Tecnologia (FCT

Effect of temperature and surfactant on the control release of microencapsulated dye in lecithin liposomes. I

The objective of our work has been the microencapsulation of dyes with lecithin from soybean, with the formation of liposomes, as a substitute for synthetic auxiliaries so as to improve the quality of the effluent. Current scenarios promote the disintegration and leakage of the liposomes, such as, changes in temperature, pH and the use of surfactants. Since dyeing process is a mix of all these parameters, we pretended to study each one separately. Rhodamine 6G fluorescence is known to be concentration quenched through the formation of non-fluorescent dimmers and, additionally, through the energy transfer from rhodamine monomer to these dimmers (3). The temperature, the surfactant and pH induce a release of the encapsulated dye resulting in rhodamine dilution and consequently alterations in the dimerization/binding equilibrium. The experimental spectra indicate that rhodamine binds almost completely to liposomes. The decomposition of the rhodamine fluorescence spectra allowed us to determine the percentage of released dye during a simulated dyeing process, and allowed us to conclude that the dimerization process occurs mainly at the inner interfaces. The amount of dye released induced by temperature changes was greater in the presence of surfactant

Argamassas com desempenho térmico melhorado

No contexto da investigação de novas tecnologias no domínio da conservação de energia surgem os “Phase Change Materials” (PCM) cuja principal característica é a mudança de fase (fase líquida para fase sólida e vice-versa) próximo à temperatura ambiente. O objecto desta comunicação é a divulgação de uma nova tecnologia, no domínio da técnica de aplicação de argamassas, que poderá ser utilizada na construção dos espaços interiores das construções. Os resultados dos ensaios efectuados mostraram que a incorporação de 25 % de PCM em peso, mantém as propriedades mecânicas das argamassas em níveis aceitáveis e é benéfica do ponto de vista térmico