Thickeners in PTFE emulsion serve four critical functions: suspension stabilization (prevents settling of dense PTFE particles), shear-thinning behavior (high viscosity at rest, low under agitation for easy coating), penetration depth control (regulates resin loading on fiberglass fabric), and film uniformity (prevents cracking during drying). Critical requirement: thickeners must decompose completely at ~380°C sintering temperature, leaving zero ash residue to maintain coating purity and electrical insulation.

Testing PTFE emulsion quality involves six key indicators: solid content (60±2% per T/FSI 067-2021), pH (9.0-11.0), particle size distribution (laser diffraction/DLS), viscosity (12-30 mPa·s at 25°C), stability (centrifugal, thermal, freeze-thaw), and appearance. This guide covers standard test methods for each parameter.