Standard reference materials: Non-Newtonian fluids for rheological measurements

NIST develops Standard Reference Materials for calibration, quality assurance and research into improved measurements. Two fluid standards are being developed to exhibit shear thinning and normal stresses typical of polymeric fluids. SRM 2490 is a solution of polyisobutylene dissolved in 2,6,10,14-tetramethylpentadecane. At this time, SRM 2491 is expected to be a poly(dimethylsiloxane) melt, giving less temperature dependence than SRM 2490. NIST will certify linear viscoelastic behavior and the shear-rate dependence of the viscosity and first normal stress difference at 0 degreesC, 25 degreesC and 50 degreesC. A round robin with the fluids will investigate variability in theological measurements. We report progress on the project.