Evaluating the effects of capacity constraints and demand patterns on supply chain replenishment strategies

This research considers inventory replenishment in a stochastic, multi-echelon supply chain involving both production and distribution functions. Simulation is used to compare distribution/material requirements planning (DRP/MRP), re-order point (ROP) and Kanban (KBN) replenishment strategies. Additional experimental factors include the demand pattern and the existence of manufacturing capacity constraints. Trade-off curves between inventory and delivery performance are generated. Statistical techniques, including analysis of variance (ANOVA), are then used to compare the areas under the trade-off curves and determine the relative dominance among the replenishment strategies. The methodology is used to identify both main and interaction effects. With seasonal demand, DRP/MRP performance is found to be best, followed by ROP and KBN, respectively. Without seasonal demand, the relative performance ranking depends on the presence of capacity constraints. Without capacity constraints, ROP performs best, followed by DRP/MRP and KBN. With capacity constraints, the ranking is reversed. This difference in behaviour can be explained using queuing analysis.     

Study of the removal of a disperse dye stain from a polyester/elastane blend

Polyethylene terephthalate and elastane fabrics were treated with azo disperse dyes in the same dyebath at 130 °C for 0, 30 and 60 min and then reduction cleared. The dyes adsorbed on each fabric were extracted using monochlorobenzene, in order to determine the amount of disperse dye in each of the polyethylene terephthalate and elastane fabrics, as the dyeing time was increased. It was observed that the amount of dye on the polyethylene terephthalate increased, while that on the elastane decreased, as the time at 130 °C increased from 0 to 60 min. After reduction clearing, the partition ratio of disperse dyes between the polyethylene terephthalate and the elastane increased. The dyed polyethylene terephthalate/elastane blend indicated that those dyes, which exhibited high partition ratios (polyethylene terephthalate:elastane), exhibited correspondingly higher wet fastness properties.     

Mass spectrometric analysis of sulphonated dyes based on diaminobiphenyls

The title dyes, a group of new homo-bireactive disazo reactive dyes having molecular masses of 1000–1400 Da, were developed because of their potential use as low salt, easy wash-off colorants for cotton. Following dye synthesis from diaminobiphenyls with and without substituents in the 2,2'-positions, negative-ion electrospray ionisation mass spectrometry (ESI-MS) was used to characterise the dyes. The MS obtained were characterised by signals arising from [M −  x H] ^{x −} ions plus fragment ions produced by cleavage at C–N bonds adjacent to the azo linkage. In addition, better results were produced when J-acid was the coupler employed rather than H-acid. The characteristic fragmentation behaviour of the studied dyes is discussed and illustrated on selected example.     

Design, synthesis and application of easy wash-off reactive dyes

New dyes that not only give good fixation levels but also relatively low substantivity in the hydrolysed form were the targets of this research. Our approach involved lowering the substantivity of the hydrolysed dye by reducing the planarity that is required for dyes to have high substantivity on cotton. In this regard, bifunctional bis-dichlorotriazine (bis-DCT) and tetrafunctional bis-monochlorotriazine/bis-sulphatoethyl sulphone [bis-(MCT/SES)] reactive dyes were made, using selected diaminobiphenyls. Bis-DCT bifunctional reactive dyes were applied to cotton by a pad–batch method, while bis-(MCT/SES) tetrafunctional reactive dyes were applied to cotton by a pad–dry–cure. Following dye application, it was found that the resultant hydrolysed dyes easily washed off the fibre surface and that the dyed cotton fabrics had colour fastness to rubbing and laundering properties that were comparable with the commercial prototypes used in this study. However, it is also apparent that the combination of relatively low water solubility and large molecular size has an adverse effect on fibre penetration.     

Studies toward a universal dye for textile fibres

A new organic dye was synthesised as part of an approach to producing a dye that could be applied to any of a variety of widely used fibre types. The dye synthesised is best described as a disperse-reactive dye and was obtained from a sequence of reactions that used an acid yellow dye as a starting compound. Dichlorotriazine was used as the reactive group in the target dye and the chemical structures of the new dye and its precursors were confirmed using ¹H NMR, mass spectrometry and FTIR analyses. In the neutral form, the dye was suitable for polyester, nylon and wool fibres. When the pH was adjusted to 9 it dyed cotton, albeit in a pastel shade only. By adding N, N -dimethylethylenediamine to the dyebath, the dye could be applied to acrylic fabric at pH 5. The fastness of the dyed fibres was also evaluated.     

Correlation between the shade of an azo disperse dye on poly(ethylene terephthalate) and poly(lactic acid) fibres with its spectroscopic properties in selected organic solvents

A series of azo disperse dyes was synthesised and the purified, synthesised dyes were characterised by proton nuclear magnetic resonance, thin‐layer chromatography and melting point measurement. The spectroscopic properties of the dyes in solution were studied by dissolving the dyes in ethyl acetate and methyl benzoate. These were seen as mimicking the environment of the dye when inside dyed poly(lactic acid) and poly(ethylene terephthalate), respectively. Reflectance spectra of the dyes on both polyester substrates were also measured in order to correlate with the spectroscopic properties of the dyes in solution. The absorbance spectra of the dyes in solution exhibited a hypsochromic (lower wavelength of maximum exhaustion) shift when dissolved in ethyl acetate, compared with methyl benzoate. The occurrence of this yellow shift was attributed to the lower polarity of ethyl acetate compared with methyl benzoate. The colour of the dyes in ethyl acetate solution was also brighter and stronger (higher molar extinction coefficients) than that in methyl benzoate. Most of the synthesised dyes exhibited high levels of exhaustion onto the two polyester fabrics. However, the visual colour yields, for those dyes having approximately the same high level of exhaustion, were different, the dyed poly(lactic acid) being stronger (higher K/S value) as well as being yellower and a trace brighter than the dyed poly(ethylene terephthalate). This difference correlated well with the solvatochromic study of the dyes in ethyl acetate and methyl benzoate solution.