Verifying Physical Recycled Polyester Content in Filament Yarns
Physical verification of mechanically recycled polyester filament relies on quantifying isophthalic acid, diethylene glycol, and sub-micron polyolefin debris.
ISO 16549
Testing Standard
Textile quality control protocols employ international standards to ensure consistent measurements of yarn irregularity. The ISO 16549 standard specifies the method for measuring the mass variation of yarn, sliver, and roving using capacitance-based instruments. It provides a uniform framework that spinning mills and buyers use to evaluate yarn evenness.
This metric is critical for predicting the appearance of the finished fabric.
Technical Procedure
The testing instrument pulls the yarn sample through a capacitor sensor at a constant speed. Variations in the mass of the yarn change the electrical capacitance between the plates. The system records these changes and calculates the coefficient of variation or the percentage of mass variation.
This output highlights thick places, thin places, and neps along the yarn length.
Industrial Use
Spinning mills run these tests on every batch before shipping to ensure the yarn meets the customer’s specifications. High irregularity leads to a patchy fabric surface and increases the risk of yarn breakages during downstream processes. Buyers refer to these standard test results to accept or reject shipments.
The data helps factories adjust their drawing and spinning frames to resolve mechanical issues. Having a standardized baseline prevents disputes between mills and garment factories by providing objective, reproducible data that can be compared across different testing laboratories.
Measurement Limit
The method is highly effective for synthetic and cotton yarns but has limitations. It does not measure the actual diameter of the yarn, but rather its mass per unit length. Wet or contaminated samples can distort the capacitive readings, producing inaccurate results.
Therefore, pre-conditioning the samples in a standard atmosphere is required before testing.