Dimensional change of wool fabrics in the process of a tumble-drying cycle

Abstract

Currently domestic tumble dryers are popularly used for drying garments; however, excessive drying and the inappropriate way of tumble agitation could waste energy and cause damage to or the dimensional change of garments. Shrinkage of wool fabrics during tumble drying causes a serious problem for wool garments. The current study investigated the shrinkage of untreated and Chlorine-Hercosett–finished wool fabrics at different drying times. Temperature of air in the tumble dryer, temperature of fabric, moisture content of fabric, and dimensional change at different drying times were measured. For the duration of the tumble drying, the rise of fabric temperature and the reduction of moisture content on the wool fabric were investigated to explore their relationship to the shrinkage of wool fabrics in the tumble-drying cycle. It was found that the tumble-drying process can be divided into different stages according to the temperature change trend of wool fabrics. The shrinkage mechanisms of the untreated and the treated fabrics were different. The dimensional change of untreated wool fabric was caused mainly by felting shrinkage during tumble drying. Chlorine-Hercosett–finished wool fabric can withstand the tumble-drying process without noticeable felting shrinkage due to the surface modification and resin coating of surface scales of wool fibers. The finding from the current research provides further understanding of the shrinkage behavior of wool fabrics during the tumble-drying process, leading to optimizing operational parameters at specific stages of a tumble-drying cycle.

The Influence of Moisture Content on Shrinkage of Wool Fabrics during Domestic Tumble Drying Process

“…The initial relative humidity of the environment was 60 (±7) %. The tumble dryer used in the study was a modified domestic thermoelectric air-vented dryer (GDZ10-977, Haier Co. Ltd, China) [4], in which the heater power, rotating speed of the drum and air flow velocity could be adjusted. Fabric load for tumble drying consisted of two untreated wool samples, two Chlorine-Hercosett treated wool samples and wool fabric ballast sufficient to make up to 2.0 (±0.01) kg load.…”

“…Usually shrinkage during tumble drying can be divided into three types [2,3]: (1) dimensional change due to relaxation; (2) dimensional change which takes place when the moisture content of a relaxed fabric is altered; and (3) felting shrinkage due to the configuration of wool surface scales. In a normal tumble drying cycle, major shrinkage of untreated wool fabric was felting shrinkage [4]. It would be interesting to investigate the effect of moisture content of wool fabric on felting shrinkage of untreated wool fabric during tumble drying.…”

The influence of mechanical action on felting shrinkage of wool fabric in the tumble dryer

“…100% wool fabric used 13 was made from 19.5 mm merino wool fibers without shrink-resistance treatment. Plain fabric was weft-knitted using a 12-gauge flat-knitting machine.…”

“…After soaking, the moisture content of the fabric load was maintained at 60.0% (AE2.5) by spinning in a Haier top-load washer. 13 The moisture content of fabric was determined to be the ratio of the mass of water to the mass of wool fabric that was conditioned at the standard atmospheric conditions.…”

“…The tumble dryer used in the study was a modified domestic thermoelectric air-vented dryer (GDZ10-977, Haier Co. Ltd, China) with adjustable parameters. 13,14 The drum radius of the tumble dryer was around 32.5 cm. At different drum rotation speeds, fabric movements varied.…”