Tx Thermal Effusivity Touch Tester

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Book a Tx Effusivity Touch Test Demo

Measuring touch properties is important for the textile industry where thermal effusivity measurements factor into marketing claim validation, R&D, and quality control. When you schedule a virtual demonstration with C-Therm, we will guide you through using the Tx Effusivity Touch Tester for your application.

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Methods for Measuring Thermal Effusivity: The Q-Max Method vs The MTPS Method

Before thermal effusivity instruments were developed, researchers relied on The Q-Max method to test the warm- or cool-touch of fabrics and other materials. The Q-Max value does not measure thermal effusivity directly—it uses heat flux to get an approximate measurement of thermal effusivity.

Repeatability and accuracy are common issues with this method as results can vary between instruments and laboratories. Additionally, manual placement of the hot sensor onto the material is a common issue as it can be difficult to establish consistent contact during the measurement process. Despite these issues, the Q-Max method provides a broad range of environmental operating conditions (humidity, pressure) that can closely mimic real-world applications.

The MTPS method measures thermal effusivity directly using a single-sided sensor. A sample is placed onto the sensor and a heat pulse is applied only after consistent contact is established, which leads to better repeatability of results.

Recent research conducted by C-Therm and the Shanghai Entry-Exit Inspection and Quarantine Bureau demonstrated a correlation between measuring materials using the Q-Max value and measuring thermal effusivity directly with the MTPS method. Comparing 16 samples, researchers found similar results between the two methods.

The advantages of using the MTPS method to measure thermal effusivity include:

• Direct measurement of thermal effusivity – Provides a calibrated measurement of thermal effusivity from a single instrument versus Q-Max, which requires using multiple calculations to get an approximate measurement of thermal effusivity.
• Fewer constraints on sample preparation – You do not need to spend long periods of time preparing the sample. You simply place the sample onto the sensor.
• Shorter test times – Whereas the Q-Max method requires approximating thermal effusivity from a series of calculations, the MTPS Method is largely hands-off: Once you place the sample on the sensor, thermal effusivity is calculated in 1 to 3 seconds.
• Simple, precise, and reproducible results – A uniform amount of heat is applied to the sample via the MTPS sensor’s guard ring technology to ensure accuracy that you can reproduce across your samples.

The Tx Effusivity Touch Tester has become the global standard for measuring the “warm-feel” or “cool-touch” of textiles and other materials. Powered by C-Therm’s patented Modified Transient Plane Source (MTPS) sensor, it is the only instrument that is recognized by ASTM International for measuring thermal effusivity.

Watch the Webinar: Using the MTPS Method to Quantify Temperature Regulation (Q-Max Correlation)

Quantifying the warm-feel and cool-touch of fabrics plays a significant role in temperature regulation for performance textiles. Watch the webinar to learn about methods for measuring heat flux, including a comparison of the MTPS and Q-Max methods.

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Applications for Thermal Effusivity in the Textiles Industry

C-Therm’s TX Effusivity Touch Tester allows researchers to quantify the thermal touch properties of textiles in order to find the materials best suited to an application, support performance claims, conduct quality control, and more.

To learn more about thermal effusivity, including how people feel it, how thermal effusivity is quantified using instruments, and how it factors into product, marketing, and research and development decisions, watch the video below.

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Textile selection with different thermal effusitivy.

Video transcript: Touch. It’s one of our critical senses in perceiving the world—everything from the clothes we wear to the bedding we sleep in. The thermoreceptors in our skin monitor and relay information to our brains about everything we come in contact with. This helps us make decisions about what feels pleasant to the touch and keeps us safe. Human skin is very good at detecting differences in a material’s ability to transfer heat, such as the warmth of a fleece sweater compared to the coolness of leather.

This material property is known as thermal effusivity—as a metric, it can be used to quantify a textile’s ability to exchange thermal energy between skin and fabric. Why is this important? Because human test panels have established a positive correlation between our touch perception of the warmth or coolness of a textile, and its thermal effusivity. In other words, our perception that certain materials will keep us warm or help us cool down is quantifiable. We know this is important in quantifying performance in a wide range of applications—including diapers, activewear, personal protective clothing, upholstery, neoprene dive suits, and bedding. Our skin’s thermoreceptors are giving us good information, though subjective.

The C-Therm Tx Effusivity Touch Tester quantifies warm and cool feel for you, making what was previously subjective into a metric that can be quantitatively measured. It provides accurate measurements across a range of real world scenarios, including higher humidity environments and under varying compressive loads. The C-Therm Tx Effusivity Touch Tester measures the science of touch—so you can provide the comfort.

C-Therm Thermal Effusivity Instruments Are Trusted Globally By Leading Textile Testing Facilities

In 2016, C-Therm worked with industry to form a new ASTM standard for characterizing the touch properties of textiles and fabrics based on C-Therm’s MTPS technique. Today, various brand companies and testing labs around the globe have adopted C-Therm’s Tx Effusivity Touch Tester into their R&D and quality control processes.

Below is a quick guide to laboratories worldwide that offer ASTM D7984 testing:

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• Intertek (Taipei, Taiwan)
• Taiwan Textile Research Institute (Taipei, Taiwan)
• Bureau Veritas (Guangzhou, China)
• Bureau Veritas (New York, USA)
• Thermal Analysis Labs (Fredericton, Canada)
• Precision Measurements and Instruments Corporation (Oregon, USA)
• Axel Products (Michigan, USA)
• Groupe CTT (Quebec, Canada)

Case Studies for Thermal Effusivity Measurement

C-Therm adapted the MTPS sensor to characterize the thermal properties of a range of textiles and fabrics. Learn more about the different applications of thermal effusivity below.

Characterizing The “Warm-Feel” Of Activewear Textiles

Manufacturers of high-performance apparel use thermal effusivity measurements to evaluate whether a material is able to keep you cool during high-energy activities, or keep you warm in colder environments. A fabric with a higher thermal effusivity feels cool, while a fabric with lower thermal effusivity feels warm. Using C-Therm’s MTPS sensor, a major Canadian retailer is able to measure the “warm-feel” of textiles in order to create thermal underwear and activewear. The table below highlights results from four candidate materials in terms of their thermal effusivity.

Characterizing The “Cool-Touch” Of Bedding Textiles

Producers of bedding textiles aim for materials with a high thermal effusivity because they can promote that their products have a “cool-touch.” Using the TX Effusivity Touch Tester, a mattress supplier tests three different coatings to determine which one has a higher thermal effusivity. The chart below highlights results from the study.

Measuring Thermal Effusivity Under Wetted Conditions

An outdoor retailer was interested in assessing how the feelings of “warmth” changed with increased moisture content. Water has a very high thermal effusivity (~1600 Ws½/m²K) compared with that of dry textiles (100 – 200 Ws½/m²K). Notice the thermal effusivity of the cotton textile is twice the effusivity of the micro-fibre material when moderately wet with 10 sprays of water. Incidentally, when fully saturated, both materials have an effusivity very close to that of water itself. This reinforces that if you fall in a cold lake, the best thing you can do to improve your comfort is to remove your clothing upon exiting. However, technical apparels such as this micro-fibre material can provide substantial improvements in comfort under moderate wetting conditions.

Testing the Performance and Comfort of Diapers

Nothing feels better on a baby’s skin than a dry, warm diaper! Diapers are made of 3 key layers: the topsheet, the surge layer, and the absorbent core. When wetted, the diaper’s surge layer disperses the liquid throughout the absorbent core, reducing the wetness from the topsheet and the overall coldness of the diaper. Thermal effusivity can quantify the diaper’s ability to exchange thermal energy between the diaper and the baby’s skin. In characterizing the thermal effusivity of the diaper under dry and wetted conditions, the performance of the diaper can be quantified as to a critical performance attribute for the product based on touch or feel. High effusivity values represent a “cool-feel” and low effusivity values indicate a “warm-feel” to the material. Water has an effusivity value of ~ 1600 W s^1/2 m^-2 K^-1, compared to a dry diaper in the range of 50-100 W s^1/2 m^-2 K^-1.

Test Results

Comfort and warmth are associated with a low thermal effusivity. Therefore, diaper companies strive to achieve the lowest possible thermal effusivity value when their diapers are dry and wetted. As seen in the chart below, the thermal effusivity increases dramatically after the diaper is wetted. However, the leading brand diaper can maintain a more comfortable feel for the baby after the diaper is wetted.

Thermal Effusivity of no name brand diapers vs leading brand diapers

Measuring Material Quality Under Compaction

When testing some fabrics, it may be necessary to measure thermal effusivity as the material is being compressed. This can be accomplished using C-Therm’s Compression Test Accessory. There is no standard level of compression available, as the level of compression is dependent on the application. Compression force is intended to measure performance under “real-world” conditions. For example, the level of compression you would use to test the insulation quality of a down jacket would be minimal compared to measuring a down sleeping bag.

Ready to Get Started with Thermal Effusivity Measurement? Get Pricing

Organizations seeking thermal effusivity measurements need to determine how to adapt instruments for their application. When you request pricing from C-Therm, you’ll also receive a customized recommendation for how to measure thermal properties for your application and industry.

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The Tx Touch Tester is part of C-Therm’s Academic Support Program. Check all the benefits and eligibility criteria here.