Problems of Protection and Comfort in Modern Apparel Fabrics

An investigation is reported in which the shrink-resistance of wool treated by exhaustion with Synthappret BAP and magnesium chloride was improved by the introduction of a strongly alkaline treatment immediately before or after the polymer-application step. The greatest improvements were observed with pre-treatments at around pH 11 or with after-treatments at around pH 10. After-treatments gave a greater improvement. The improved shrink-resistance was attributed to the promotion by alkali (in the bath, or carried over on the fibres) of reactions of the carbamoyl sulphonate groups in Synthappret BAP with themselves (cross-linking) or with the fibre.

Alkaline pre-treatments were considered to be more practical than after-treatments. They could be simply incorporated into the normal Synthappret BAP–magnesium chloride exhaustion-processing sequence by a change from a neutral or mildly alkaline scour with non-ionic detergents to a preliminary scour with sodium carbonate or metasilicate solution at pH 11.

Alkaline pre- and after-treatments were examined with a range of other exhaustion shrink-resist finishes for wool based on polymers the only other case to show improved shrink-resistance was the batch Hercosett 125 treatment of chlorinated wool, and that only at low chlorination levels. In a comparison of a selection of exhaustion shrink-resist treatments on untreated wool, the most effective (for the amount of polymer applied) on the fabrics studied was Synthappret BAP—magnesium chloride coupled with an alkaline after-treatment.     

Effect of coke reactivity and nut coke on blast furnace operation

Abstract

Two measures for coke saving and increase in blast furnace efficiency related to coke characteristics – reactivity and size – are discussed in this paper. Modern blast furnace operation with low coke rate and high injection rate causes a change in coke quality requirements. A discussion has arisen recently about highly reactive coke. Here, a theoretical analysis of influence of coke reactivity on the thermal reserve zone, direct reduction and carbon consumption in the blast furnace has been undertaken. Experiments have been performed using non-standard test scenarios that simulate coke behaviour under real blast furnace operating conditions. Coke reactivity and microstructure have also been investigated under the impact of alkali and pulverised coal ash and char. Operation of many blast furnaces has proved the possibility of coke saving and increase in productivity when using small-sized coke (so-called nut coke) mixed with the burden, but the reasons for this phenomenon, and consequently the limit for nut coke consumption, are still not very clear. An analytical method and cold model simulations have been used to quantify the change in shaft permeability and furnace productivity when using nut coke.     

New method to determine optimum water content for iron ore granulation

Abstract

Granulation is necessary before iron ore sintering. The optimum granulation moisture added to the mixture of iron ores, fuel and coke for obtaining suitable size distribution of the granules after tumbled in a drum is of vital importance for the sintering. In order to investigate the optimum moisture content, the moisture capacity of the iron ore, which means the maximum water content held in iron ores of unit mass, is defined and measured in a self-designed apparatus. The relationship between the moisture capacity and some other characteristics of iron ores, which include mineral and chemical composition, size distribution and mineralogy, is discussed. It was found that the mineral composition and the size distribution of the iron ore particles greatly influence the moisture capacity of the iron ores. The moisture capacity of the iron ore was also applied to optimise the granulation by finding the relationship between the moisture capacity of the mixture and the optimum water content. The moisture capacity has positive correlation with the optimum water content. The iron ore, which has high moisture capacity, needs more water added in the granulation process in order to get high permeability. The correlation was given to predict the optimum water content in the granulation based on the moisture capacity measurement.     

Finite element model of thermal stress effects onstress distributions in rubber modified glassy polymers. Part 1 – Single particle model

Abstract

A single particle finite element model has been used to analyse the effects of thermal stresses on the stress distributions near the interface between the rubber particle and the matrix in rubber modified polymers. The thermal stresses are due to the mismatch of thermal contraction between the rubber particle and the matrix during cooling. The study is to determine whether the thermal stresses are significant enough to affect the distribution of normal stress and von Mises stress at the particle/matrix interface. Results from the single particle model show that a temperature decrease of 60 K, i.e. from 100 to 40°C, can generate a circumferential compressive stress at the particle/matrix interface, which is of the same magnitude as the tensile stress required to cause failure in most of the glassy polymers. Although the effect on the circumferential normal stress is significant, its effect on the von Mises stress is very small. The results also show that when the cavitation occurs in the rubber particle, the thermal stress effect is drastically reduced. This study provides encouraging evidence for the importance of thermal stresses in determining the stress distributions in rubber modified polymers and suggests that thermal stresses should be considered in the deformation analysis of these materials.