Microgel-based surface modifying system for stimuli-responsive functional finishing of cotton

An innovative strategy for functional finishing of textile materials is based on the incorporation of a thin layer of surface modifying systems (SMS) in the form of stimuli-sensitive microgels or hydrogels. Since the copolymerization of poly(N-isopropylacrylamide) with an ionizable polymer, such as chitosan, results in a microgel that is responsive to both temperature and pH, the microparticulate hydrogel of poly-NiPAAmchitosan copolymer (PNCS) was synthesized using surfactant-free emulsion method. The microparticle size in dry (collapsed) state is estimated at 200nm by SEM and TEM, and effect of temperature and pH on microparticles was investigated by DLS and UV–vis spectrophotometry. The incorporation of PNCS microparticles to cotton material was done by a simple pad-dry-cure procedure from aqueous microparticle dispersion that contained 1,2,3,4-butanetetracarboxylic acid (BTCA) as a crosslinking agent. This application method provided sufficient integrity to coating by maintaining the responsiveness of surface modifying system. The stimuli-responsiveness of modified cotton fabric has been confirmed in terms of regulating its water uptake in dependence of pH and temperature

Attachment of β-Cyclodextrins on Cotton and Influence of β-Cyclodextrin on Ester Formation with BTCA on Cotton

Cotton was treated with β-cyclodextrin (BCD) and two derivatives of β-cyclodextrin (2-hydroxypropyl-β-cyclodextrin and monochlorotriazinyl-B-cyclodextrin) to assess the optimal type for fixation with cotton. The experimental results showed that treatment of cotton with BCD using the crosslinker BTCA resulted in higher fixation than the treatments with the other two derivatives. The concentration of BTCA used did not significantly influuence the amount of fixation of BCD on cotton. FTIR-ATR spectroscopic analysis showed that the amount of ester formed on the fabric was influenced by the addition of BCD on cotton with BTCA in comparison to crosslinking of only BTCA with cotton. The laundering tests showed relatively poor washfastness of the β-cyclodextrins on the fabrics

Integrated approach to optimization of an ultrasonic processor

In an ultrasonic processor, the input electrical energy undergoes many transformations before getting converted into the cavitation energy, which is dissipated in the medium to bring out the physical/chemical change. An investigation of the influence of free and dissolved gas content of the system on the efficiency of this energy transformation chain is attempted. The results of the experiments reveal that the cavitation intensity produced in the medium varies significantly with the gas content of the system. A unified physical model, which combines basic theories of acoustics and bubble dynamics, has been used to explain the experimental results. An attempt has been made to establish the mechanism of the steps in the energy transformation chain, the involved physical parameters, and interrelations between them. It has been found that the influence of free and dissolved gas content of the medium on the overall energy transformation occurs through a complex inter-dependence of several parameters. Thus, simultaneous optimization of individual steps in the energy transformation chain, with an integrated approach, is necessary for the optimization of an ultrasonic processor. The present study puts forth a simple methodology, with the gas content of the system as manipulation parameter, for this purpose

Acoustical characteristics of textile materials

An attempt is made to identify the acoustical characteristics of textile materials using precision woven monofilament fabrics as model textiles. The experiments try to eliminate the effect of entrapped air pockets in the fabric on an ultrasound wave field. The results of the experiment reveal that the power consumption of the ultrasound horn remains practically constant after introducing the textile at different positions in the standing wave field. Measurements of transmitted acoustic pressure amplitude through the textile reveal that fabrics form an almost transparent boundary for acoustic waves. A simple model involving the structural and hydrodynamic characteristics of the textiles is proposed to determine their acoustic impedance, and the results of the experiments are explained on the basis of this model. The overall conclusion of the study is that in the absence of entrapped air, textiles do not have any individual impact on the ultrasound wave field. \ud \u

The added value of 3D polymer deposition on textiles

The working hypothesis for this research project is that it is possible to develop a new functional polymer printing process for the direct application of conductive polymer onto textiles. We will use the basic extrusion technology that is currently applied in 3D printing. Thus the aim is also expanding the knowledge and knowhow base of 3D printing and make this technology applicable for deposition of functional polymers on textiles in such a way that process parameters are clearly understood, and pre-defined final product specifications can be met. Thus the challenge is to apply conductive tracks with a simple one step process that fits the current textile production processes. This means that investigating polymer deposition onto textiles of bio based polymers like PLA, doped with carbon could be a versatile route to achieving economic and sustainable conducting textiles. If the mechanism underlying the bonding of doped PLA with textiles can be controlled for processing then a new route to achieving conductive grids would be opened.Paper written by the Saxion chair Smart Functional Materials and The Unversity of Twente for and accepted by the Autex Conference 2013 (22-24 May 2013, Dresden, Germany)

Model system for mechanistic study of catalytic bleaching of cotton

We have dcveloped a homogeneous model system to study the mechanism of hydrogen peroxide bleaching using [Mn2O3(N,N'N ''-trimethyl-1-1,4,7-triazacyclononane)(2)](PF6)(2) (MnTMTACN) as catalyst. Thee primary model pigment exarnined is morin (3,5,7,2',4'-pentahydroxyflavone) owing to its presence in native cotton 1-iber. Additionally, a series of model compounds with systematic structural diffierences are examined in order to facilitate the development ofa mechanistic understanding of the bleaching system. The pigment oxidative degradation reaction is monitored by UV-Vis spectrophotornetry. The influence of pH is examined in both hornooeneous and heterogenous model systems. The use of MnTMTACN catalyst enables low-temperature hydrogen peroxide bleaching of cotton fabric at slightly lower pH values