Colour change fibre

The compound exists normally as the trans or ( )-isomer 21a. This molecule is essentially planar both in the solid state and in solution, although in the gas phase there is evidence that it deviates from planarity. When irradiated with UY light, the ( )-isomer undergoes conversion substantially into the cis or (Z)-isomer 21b which may be isolated as a pure compound. In darkness, the (Z)-isomer reverts thermally to the (F)-isomer which is thermodynamically more stable because of reduced steric congestion. Some early disperse dyes, which were relatively simple azobenzene derivatives introduced commercially initially for application to cellulose acetate fibres, were found to be prone to photochromism (formerly referred to as phototropy), a reversible light-induced colour change. C. I. Disperse Red 1 (22) is an example of a dye which has been observed, under certain circumstances, to give rise to this phenomenon. 

A better alternative would be to have fibres that in their own right could show multiple colours based on the direction of view. One model for this is a fibre that consists of a concentric core and a sheath, each made from different types of polymers. For instance, constructing a fibre where one fibre is acid dyeable nylon and the other basic dyeable nylon make it possible to dye the sheath and the core in different colours. The colour change i.e. hue shift) then varies with the angle of incidence of light on the fibre. 

Fibre is not decolonsed but colour changes A nthraquxnone Class Colour Of reduced fibre is... 

W ood meal may be detected in mixtures by the microscope or by the phloroglucinol test. One gram of phloroglucinol is dissolved in 1 c.c. of alcohol, and 10 c.c. of syrupy phosphoric acid is aorcolain dish. Wood fibres show a rose colour changing to carmine. Apart from wood meal other forms of meal (corn, potato) arc similarly used. 

Many commercial dyes contain one or more sulfonic acid groups to confer water solubility to the dye and assist in binding the dye to the polar fibres in the textile (cotton, nylon, silk, wool, etc.). An example is Congo Red (12) (Figure 3). This is red in alkaline solution thus, the sodium salt will dye cotton red, but it is very sensitive to acids and on acidification the colour changes from red to blue, and so this compound is also used as a type of indicator. Vat dyes, known as sulfur dyes, can be prepared by heating various organic compounds, e.g. amines, aminophenols, and nitrophenols, with sodium polysulfide. 

As a result of obtained PETP - fibres testing it has been found that colour resistance to light is 4-5 marks and to wet treatment it is 5/5/5, where the first index is colour change, the... 

In this context, in which colour is displayed at the right time, as opposed to the context in which colour is a constant, prerequisites to building sensors have been satisfied, and assuming that these dyes are applicable to textile fibres and substrates, these sensors are the core of a smart textile. In-depth definition of the level of smartness reveals that, other than the visible colour change, no further action is taken from the sensor, which is why the technology is often referred to as passively smart (Bresky et al., 2008). 

Other successful electrochromic devices have been realized by Kelly et al. using polyaniline-impregnated fibres [79]. In situ electrochemical polymerization of polyaniline is used to bind poly aniline to a PET or viscose spacer fabric. The fabric is then impregnated with an electrolyte and sandwiched between two electrodes. For the bottom electrode, carbon black or silver ink can be printed directly on the fabric. Polyaniline colour changes from green to blue through oxidation—reduction processes. However, the lifetime of this structure is also short and does not exceed dozens of oxidation—reduction cycles. 

Several technologies able to be used for the development of communicative textile devices have been presented. Some of them are already used for the development of textile displays. Their emission of reflective characteristics allow their use for different types of applications. Emissive devices such as luminescent stmctures or optical fibres are preferred for high-visibility outfits for personal safety, for art and fashion design or for advertising events. Reflective devices offer a softer, more discreet colour change, which could preferentially be used for everyday applications such as communicative clothes, home furnishings or fashion. 

Preaccelerated, low viscosity, thixotropic isophthalic resin, suitable for hand-lay and spray/projection lamination, combining long pot-life with very rapid cure at low exotherm in thick sections, and offering rapid, efficient fibre wet-out. a low temperature cure and a colour change on curing. Approved by Lloyd s Register of Shipping. 

Bonds (plus a gap-filler), fibre-reinforced composites, plus wood, steel, aluminium and concrete. Available for use with 3 different hardener systems, 273, 275 and 277 offering different gel and cure time. Dual cartridge system eliminates measuring and mixing. Colour change denotes full cure. 

This is demonstrated in fig. 1, where an optrode designed to operate as an ammonium detector for drinking water is shown. A chemical reaction in which ammonia (NH3) which is in equilibrium with ammonium ion (NH4 + ) in the solution leads to a change of the colour of an indicator molecule immobilised at the end of a quartz fibre in a membrane. This colour change, which is a function of the concentration of ammonium ion present in the solution, causes enhanced absorption of the mono-chromatic light which is transported by fibre optics to the membrane and back to a detector unit. 

A patent from 1982 describes a treatment of acrylic and modacrylic fibres to produce a copper sulphide element that confers electrical conductivity (Gomibuchi et al., 1982). A patent from 1980 describes the use of copper iodide to produce an electrically conductive fibre without substantial colour change (Tanaka and Tsunawaki, 1981). 

Optical enzyme sensors are designed preferably as extrinsic sensors, i.e. as op-todes. There are, however, some examples of intrinsic sensors. As an example, an optical fibre has been described which was manufactured on the basis of a polystyrene fibre coated with adsorbed enzyme and indicator molecules. The colour changes brought about by the enzymatic reaction was detected using the evanescent field. 

In smart polymer applications in textiles, PCMs and colour change polymers mostly take the form of microcapsules. A microcapsule is an intermediate state which is added to solutions, fibres, films and nonwovens to incorporated a smart function into the textile. These materials may be incorpated into textiles by printing, coating and dyeing. For printing and coating, the materials are microencapsulated first and then coated or printed onto the fabric surface by common methods such as the pad-dry-cure process. 

A kind of solvate chromism fibre was reported, whose colour changes when in contact with a liquid, for example water. These materials are used for design swimsuits. Apart from this, the most important application for chromic materials is to create fantasy designs which change colour depending on the wavelength of incident light. 

Luminescence differs from chromic effect in that luminescence is not a colour change but emits light. Opticoluminescence is a typical effect encountered in optical fibres. Opticoluminescent fibres have been widely used in textiles for the function of accurately monitoring body and environmental conditions. Recently photonic crystal fibres (PCFs) have been introduced. The cross-section of the PCF contains either periodically arranged micron-scale air voids or a periodic sequence of micron-scale layers of different materials. " PCFs can appear coloured due to optical interference effects in the microstructured regions. 

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