New Measurements of the Viscosity of Diisodecyl Phthalate Using a Vibrating Wire Technique

Abstract

Diisodecyl phthalate (DIDP) has been proposed as a suitable reference material for industrial application in the region of moderately high viscosity. The paper reports a new set of viscosity measurements of a 99.5 % GC sample of this substance, which are directly traceable to the primary standard reference valuethe viscosity of water at 293.15 K. The present measurements, performed with a vibrating-wire sensor, were carried out at atmospheric pressure over the temperature range (283 to 313) K. Over this temperature range, the viscosity varies from approximately (37 to 267) mPa·s. The measurements have been carried out with an instrument that has already been the subject of improvement since the first measurements were performed, and it relies upon calibration exclusively against the primary standard of viscometry. The estimated overall uncertainty of the results does not exceed ± 1 %, over the whole range of the measurements and, for the results obtained at temperatures in the vicinity of 293 K, is ± 0.8 %. The higher quality of the present measurements, and their direct traceability to the primary reference value for viscosity, justifies the replacement of our earlier set of preliminary data on DIDP viscosity.

Tris(2-ethylhexyl) trimellitate (TOTM) a potential reference fluid for high viscosity. Part I: Viscosity measurements at temperatures from (303 to 373) K and pressures up to 65 MPa, using a novel vibrating-wire instrument

“…These estimates were partly based on previous sensitivity studies [19,20,45,46]. The repeatability of the measurements, at the same confidence level, is better than AE0.2% for the lowest viscosity, increasing to a maximum of AE0.4% for the highest viscosity.…”

“…A lock-in amplifier (Perkin-Elmer, model 7225) was used both as a synthesizer of the variable-frequency driving current and as a multimeter to measure the voltage drop across the vibrating wire sensor, as described before [18,19,45,46]. A 100 V resistor (grade S standard resistor type 3504D from H. Tinsley & Co. Ltd. U.K.) was connected in series with the sensor.…”

“…A new vibrating wire sensor for measuring viscosity at high pressures and at temperatures up to 373 K was designed, based on the vibrating wire sensor validated by Caetano et al [47], which was used for accurate viscosity measurements up to 500 mPa s, with molecular [8,19,47] and ionic liquids [33,45,46], after calibration with the viscosity primary reference, water at 293.15 K and 0.1 MPa. However, the later sensor was designed for atmospheric pressure measurements.…”

“…Studies carried out by Caetano et al [18][19][20] have pointed out the potential qualities of diisodecyl phthalate (DIDP) to be an industrial viscosity reference liquid of moderately high viscosity. As a consequence, Caetano et al [8] have recently proposed, under guidance of IATP, DIDP to be an industrial reference fluid for viscosity at 0.1 MPa, in the range of temperatures from (293 to 303) K, comprising a range of viscosities from (65.0 to 123.0) mPa s. Subsequently, high pressure viscosity and density measurements of DIDP were also published [21][22][23][24][25][26][27].…”

An Industrial Reference Fluid for Moderately High Viscosity

“…11,12 As a consequence of this production process, samples of DIDP, such as those used in the present work, are isomeric mixtures, as has been reported before 11,13,14 and has been verified by some of the present authors. 15,16 The qualitative studies conducted both in Portugal 15,17 and Australia 16 entailed 13 C NMR and GC-MS analysis. In the latter case, a description of the equipment used in the study has been made in ref 16.…”