The characteristics of fibers within a yarn play an important role in the yarn's functional and aesthetic properties. Modifications to these fibers may affect the properties of the yarn in a number of ways. During the development and post development of yarns, tensile tests are performed to ASTM D3822 to evaluate mechanical properties of the fibers or filaments. Tensile testing is also conducted during manufacturing as a quality control measure to confirm that material is within specifications.
When working with very fine textiles, it is often difficult to determine the most suitable test configuration. It is important to select grips that will allow you to easily install and remove specimens. In some cases, creating tabs with tape may make it easier to install the specimens. This is especially true when specimens are so small that they are difficult to see with the naked eye. If the proper grip is used, specimen slippage or specimen failures within the grips should not occur.
Individual fibers can be very delicate and may fail at very low loads. It is important to select an appropriate load cell that will allow maximum accuracy at low forces. In cases such as this, Instron’s 5N load cell is the best option.
There are a variety of grips that are appropriate for single strand fibers. If specimens are long enough, we recommend cord and yarn style grips, which reduce the chances of premature specimen failure and help maintain alignment. 50 N pneumatic side acting grips are also potentially suitable for this application, and can be used in many cases.
The challenges of testing to this standard are:
- Specimen gripping
- Low load values
- Instron pneumatic cord and yarn grips are well-suited to gripping many types of fiber specimens while maintaining high throughput
- Instron offers traditional side acting pneumatic grips as small as 50N capacity, which are ideal for testing delicate fibers with low break loads
- Instron’s 6800 Series is able to measure forces down to 0.1% (1/1000th) of the load cell's capacity, enabling the accurate measurement of very low forces
It is important to review ASTM D3822/D3822M-14 in order to fully understand the test setup, procedure, and results requirements.