ASTM D5591-22

5.1?This test method may be used for the acceptance testing of commercial shipments of yarns and cords.

5.2?Experience shows that yarns or cords on would packages, usually being under tension, exhibit a contraction in length (and a resulting increase in linear density) when removed from the package and allowed to relax over a period of time at room temperature. Consequently, it they are tested without being allowed to relax, they will register higher thermal shrinkage force values as the relaxation shrinkage will be incorrectly included as the thermal shrinkage force.

5.3?The thermal shrinkage force of nylon, polyester, and aramid fiber is related to the polymer of origin and its manipulation in processing. Thermal shrinkage force measurement can be used to control product uniformity.

5.4?The level of thermal shrinkage force is critical in the user's subsequent operations, such as the drum-set (original length of cord) required to build a tire of a particular size.

5.5?The thermal shrinkage force is critical to the final shape and size of fiber-reinforced articles. For example, thermal shrinkage force affects the final size of V-belts and their ability to maintain tension during their operation.

5.6?This test method is in agreement with the nominal procedures of Test Methods D885/D885M for the determination of thermal shrinkage force in yarns and cords.

1.1?This test method covers preparation and procedures to measure the thermal shrinkage force of yarns and cords in air.

1.2?This test method is applicable to measurement of the thermal shrinkage force of yarns and cords whose shrinkage force at 180 ? 2 ?C (355 ? 4 ?F) in air does not exceed 20 N (4 lbf). This test method is applicable to nylon, polyester, and aramid yarns and cords within the applicable range of thermal shrinkage force, as well as to comparable yarns and cords from other polymers.

1.3?The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.

1.4?This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5?This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.