Elsevier

Polymer Testing

Volume 25, Issue 5, August 2006, Pages 677-689
Polymer Testing

Test Method
An improved test method for characterizing the dynamic liquid moisture transfer in porous polymeric materials

https://doi.org/10.1016/j.polymertesting.2006.03.014Get rights and content

Abstract

In order to evaluate the moisture management capacity of porous polymeric materials such as fabrics, a new test method and an instrument called the moisture management tester (MMT) have been developed. Derived from the measurement curves, 10 indices are defined to characterize the fabric liquid moisture management properties. In the improved test method, six indices are re-defined. The grading and classification methods are studied to give a direct overall evaluation and result for the liquid moisture management properties of the tested fabrics. Also, an improved sensor design, data processing method and expression of test results for the fabric moisture management properties are introduced. The MMT provides an objective measurement of comfort for those fabrics claimed to have excellent moisture management properties. It also provides a detailed and reliable method for production quality control, new product development and quality assurance by the retailer.

Introduction

Comfort and superior functional performance of clothing are very important attributes demanded by modern consumers, especially under dynamic wear situations. The moisture management capacity of clothing and certain other porous materials is one of the attributes identified as being very important under sweaty wear situations and in dealing, e.g., with urinary incontinence [1]. This moisture management capability is related to the comfort, the thermal and chemical protection, protection against bacteria and viruses, and the performance and physiological stresses of human beings.

Wong et al. [2], [3] identified three major sensory factors that influence a human's subjective perception of clothing comfort, namely thermal–wet comfort, tactile comfort and pressure comfort, of which the thermal–wet comfort factor explains about 50% of the total variance of comfort. Therefore, in order to improve today's clothing performance in relation to clothing comfort, it is important to investigate the relationship between liquid moisture management properties and perception of moisture sensations [4].

Fabric liquid moisture transport properties in multi-dimensions, referred to as moisture management properties, influence the human perception of moisture sensations and comfort significantly. The moisture management properties of porous polymeric materials depend on their water resistance, water repellency, water absorption, the wicking of the fibers and yarns, as well as the geometric and internal structures of the constituent materials such as fibers and yarns [5]. Certain standards and test methods can be employed to evaluate the fabric's simple absorbancy and wicking properties, and the liquid strike-through time of nonwovens also can be tested according to ISO 9073–8. However, the existing standards are unable to measure the dynamic behavior of liquid transfer in clothing materials.

To objectively characterize the spread of moisture and the transfer properties on and between fabric surfaces, a new instrument, named the moisture management tester (MMT), was developed [6]. Hu et al. reported the measuring principle and apparatus design of the MMT and the definition of performance indices, and studied the relationships between subjective perceptions of moisture sensations in sweating, such as “clammy” and “damp”, and the liquid moisture management properties measured by MMT [7]. However, after conducting a large number of experiments, it was found that the reliability of the sensors should be improved and the definitions of some of the indices needed to be modified. Further, in the development of testing standards for industrial applications, it is required to grade the tested materials and classify them into different categories. Therefore, this paper focuses on the improvement of the test method and the evaluation of indices of liquid moisture management properties, grading and classification methods, data processing and the expression of test results for industrial applications.

Section snippets

Measurement principle

The principle employed by the MMT is based on the fact that when moisture transports through a fabric, the contact electrical resistance of the fabric will change, and the value of the resistance change depends on two factors: the components of the test solution and the water content in the fabric. When we fix components of the test solution, the electrical resistance measured is related to the water content in the fabric.

The electrical resistance of porous polymeric materials is usually very

Data pretreatment

The raw data acquired during measurement are affected by noise which influences the evaluation of the fabric moisture management properties. Therefore the data require pretreatment to effect reduction of this noise.

To achieve this, crassitude error processing and a smoothing method are applied:

  • (1)

    Crassitude error processing: the median filter method is used in crassitude error processing.

  • (2)

    Data smoothing: both the moving average method and sample line processing are applied in data smoothing.

Fig. 2

Evaluation criteria and indices

The MMT can measure the dynamic liquid transport properties of porous polymeric materials, such as fabrics, in three dimensions:

  • (1)

    Absorption rate: moisture absorbing time of the fabric's inner and outer surfaces.

  • (2)

    One-way transportation capability: liquid moisture one-way transfer from the fabric's inner surface to its outer surface.

  • (3)

    Spreading/drying rate: speed of liquid moisture spread on the fabric's inner and outer surfaces.

Fig. 3 shows typical curves of water content vs. time.

Based on the test

Grading and classification method

In the development of testing standards for industrial applications, it is required to grade the test results of the tested samples. Moreover, the fabrics with different features are required to be classified into different categories.

Expression of test results

The test results for the liquid moisture management properties of the tested fabrics can be expressed by means of the water content chart with index table, the fingerprint with the classification result, the multi-measurement profile and the map of water location.

(1) Water content chart with MM (moisture management) index table. The chart of water content vs. time (Fig. 3) directly expresses the water content changes against time and gives initial results of the fabric moisture management

Conclusion

The test method and a prototype equipment called moisture management tester (MMT) were developed to objectively measure and characterize the liquid moisture management properties of porous polymeric materials such as fabrics. Derived from the test data and the measurement curves, a series of indices are defined and calculated to characterize liquid moisture management performance. In the improved test method, six indices are re-defined. All indices are graded and converted from value to grade

Acknowledgments

We would like to thank the Hong Kong Polytechnic University for the funding of this research through the projects A188 and A174.

Reference (7)

  • Y. Li

    The science of clothing and comfort

    Text. Prog.

    (2001)
  • A. Wong, Y. Li, K.W. Yeung, Psychological sensory perceptions and preferences of young adults towards tightfit...
  • A.S.W. Wong, Y. Li, Comparison of different hybrid models’ performances in prediction of overall clothing comfort from...
There are more references available in the full text version of this article.

Cited by (120)

  • Continuously fabricated nano/micro aligned fiber based waterproof and breathable fabric triboelectric nanogenerators for self-powered sensing systems

    2022, Nano Energy
    Citation Excerpt :

    Accordingly, its one-way transport index (R) was negative with a value of − 633.7%. Results suggested that PVDF/PTFE TENG possesses poor water transport performance, which is divided into a water-repellent fabric [41]. Additionally, PCL TENG, with a R value of − 1831%, belongs to a water-proof fabric (Fig. 2i).

View all citing articles on Scopus
View full text