Measuring Cyclic Oligomer Content in Synthetic Filament Extracted Yarns
Solvent extraction coupled with liquid chromatography isolates synthetic yarn cyclic oligomers to set strict delivery specs and stop knitting deposit failures.
Draw Texturing Oligomer Migration
Trimer Accumulation
Low molecular weight cyclic polyester compounds migrate from inside synthetic filaments to yarn surfaces during high temperature mechanical stretching. The occurrence of draw texturing oligomer migration deposits powdery cyclic trimer residues onto friction discs, yarn guides and heater plates. Accumulation of these crystalline deposits increases yarn friction, causes filament breakage and generates non-uniform yarn tension during high speed texturing.
Filament Diffusion
High temperature heating zones in texturing machinery soften the polyester matrix, increasing macromolecular mobility within the oriented filaments. Cyclic trimers diffuse rapidly along micro-voids toward the cooler filament surface during simultaneous drawing and false-twist texturing operations.
Package Specking
Deposited trimers detach from yarn surfaces during subsequent knitting or weaving operations, clogging needle beds and reed wires. In package dyeing, loose oligomer dust precipitates inside yarn packages, creating chalky white deposits that cause un-level dyeing and filtration specks on dyed fabrics. Mills perform solvent extraction tests on textured yarn packages to quantify surface oligomer loads before sending yarn to dyehouses.
Scouring treatments with specialized dispersants remove surface trimers prior to high temperature dyeing cycles.
Scour Threshold
Thermal history during fiber spinning and texturing governs the volume of cyclic trimers available for surface migration. Complete elimination of oligomers remains impossible due to chemical equilibrium during polyethylene terephthalate synthesis. Scouring treatments reduce surface deposits but cannot prevent further oligomer migration during subsequent high temperature fabric heat setting.