Ivana Salopek Čubrić

Impact of raw material, yarn and fabric parameters, and finishing on water vapor resistance

The objective of this study was to explore a number of technical–technological parameters affecting the water vapor resistance of knitted fabric and clothing, as well as to develop a predictive model that describes the prominent affecting parameters. Thirty-four knitted fabrics were carefully produced and measured on a sweating guarded hotplate and thermal manikin. The study focused on the influence of the following parameters on the transfer of water vapor: type of textile fibers, yarn and knitted fabric parameters, finishing of fabrics (recipes include bleaching, dyeing, and softening), and body activity. The statistical analysis, performed to examine the relationship between observed parameters, indicated medium correlation between water vapor resistance and moisture regain (R = 0.7). Furthermore, the relationship between water vapor resistance and the following knitted fabric parameters is especially prominent: mass per unit area, knitted fabric thickness, and tightness factor (R = 0.9). When the fabrics are made into ensembles, however, effects of material differences become small and the differences between garments more difficult to discriminate; even more so when movement is present.

Thermal resistance of polyurethane-coated knitted fabrics before and after weathering

Polyurethane-coated knitted fabrics are of interest because they exhibit several positive properties, they are more stretchable, elastic and comfortable than coated woven fabrics and yet they are little studied. Information of weather durability, as well as thermal properties, is essential to ensure thermal protection for textile materials intended for outdoor use. In the presented research, a series of coated knitted fabrics for protective clothing were developed and exposed to weathering in summer and winter seasons. After three months of outdoor exposure, thermal resistance of all the tested materials decreased by 13% after the summer season and 25% after the winter season. A very good correlation of knitted fabric mass per unit area and thermal resistance of knitted fabric, coated fabric and aged coated fabric occurred. The studied materials experienced a partial degradation of the polyurethane layer, which is not related to the deterioration of the knitted substrate. The presented investigation of thermal resistance of coated fabrics and their dependence on the knitted substrate, as well as the influence of environmental conditions, allows the improvement of coated fabrics with the aim of better thermal protection.

The Simulation of Heat and Vapour Transfer Trough Fibrous Materials

The heat and water vapour transmitting properties of fibrous materials are important factors that affect the clothings comfort as well as the quality of special functional clothing that is worn in extreme environmental conditions. The paper introduces advanced system for the simulation of physiological processes that appear next to the human skin. Its use enables the measurement of heat and vapour transfer trough fibrous structures, as well as determination of vapour permeability and permeability index. The experiments reported here refer to the measurement of a number of fibrous materials used for the next-to-skin wear. For the measurement have been produced materials that differ either in their structure or raw material in order to observe the influences of different parameters to the transfer properties. The transfer trough fibrous materials is mainly affected by its structure that comprises of a repeat units with cellular geometry containing air pores, yarns that form basic structure and intersection points of two or more yarns. Therefore, the structure of materials is also investigated and described by means of fabric moduli. Dynamics of heat and vapour transfer is observed through the experimentally obtained data and the influence of a number of structural parameters is discussed. The statistical methods are used to qualify the effects of investigated variables on the heat and vapour resistance.

Impact of substrate on water vapor resistance of naturally weathered coated fabrics

The aim of the study was to investigate changes of water vapor resistance of coated fabrics with different knitted substrates. For the study different knitted structures were designed and produced, while the conditions for the coating process were kept constant. All structures were exposed to natural weathering in the summer and winter seasons. Thus, the experimental setup enabled the comparison of changes in water vapor resistance of various structures as a result of aging, as well as giving an insight into the differences in resistance after aging in different seasons. After exposure, changes in fabric mass per unit area, thickness and water vapor resistance were observed. The outcomes of the study gave a good insight into the behavior of coated fabrics and may be used when protecting coated materials in order to improve their performance.

Effect of finishing treatments on heat resistance of one- and two-layered fabrics

A series of cotton knitted fabrics was produced and finished according to three different recipes in order to compare the changes of their heat resistances. The heat resistance was measured using the sweating guarded hotplate. Measurements were carried out on one layer of produced knitted fabrics, as well as on two layers of fabrics. The results indicated significant influence of all carried finishing treatments to the decrease of heat resistance of knitted fabrics. It was shown that the high influence of finishing treatment to the total heat transfer trough fabric remains if the fabric is worn with additional knitted fabric layer. The presented results and performed statistical analysis indicated significant effect of finishing treatments to the changes of fabric parameters and furthermore to the changes of heat resistance what directly affects the total thermophysiological comfort of knitwear.