Effusivity’s Role in Temperature Regulation Performance of Textiles (Q-Max Correlation)


Thermal Effusivity (sometimes called “heat penetration coefficient” or “thermal inertia”) is defined as the rate at which a material can absorb heat. It is the thermophysical property that determines the contact temperature of two semi-infinite media that are touching each other.  The property is measured with the use of C-Therm’s MTPS (Modified Transient Plane Source) sensors. Effusivity is a critical performance attribute of textiles intended to improve thermal regulation of the end user. Learn more about how product managers, innovation teams and researchers in claims validation are employing the patented MTPS sensor technology in characterizing the “Warm Feel” or “Cool Touch” of textiles. 

We’ll review the background of this method, and the development of the ASTM D7984 standard for measuring effusivity as it relates to “Warm Feel” / “Cool Touch”. We’ll additionally present recent correlative data with a technique that approximates the “Warm Feel” through a different heat flux measurement. The Q-max value was introduced in the early 1980’s as a measure of predicting warm/cool feeling of fabrics by Kawabata and his team. Q-max is the peak value of heat flux which flows out of a copper plate having a finite amount of heat into surface of fabric after the plate contacts the fabric surface. This property is used to estimate the thermal sensation when skin touches fabrics. The measurement is proportional to the fabric’s thermal effusivity. Join us online in reviewing recent test results on 15 textile materials in comparing the thermal effusivity and Qmax values of those materials. A discussion on the similarities and points of difference between the two methods will be presented. This webinar is recommended to anyone working in the product performance testing of textiles and fabrics where temperature regulation is an important function.

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