Assessment of Piezoelectric Sensors for the Acquisition of Steady Melt Pressures in Polymer Extrusion

Abstract

Piezoelectric sensors have made their way into polymer processing and rheometry applications, in particular when small pressure changes with very fast dynamics are to be measured. However, no validation of their use for steady shear rheometry is available in the literature. Here, a rheological slit die was designed and constructed to allow for the direct comparison of pressure data measured with conventional and piezoelectric transducers. The calibration of piezoelectric sensors is presented together with a methodology to correct the data from the inherent signal drift, which is shown to be temperature and pressure independent. Flow curves are measured for polymers showing different levels of viscoelasticity. Piezoelectric slit rheometry is validated and its advantage for the rheology of thermodegradable materials with viscosity below 100 Pa·s is highlighted.

In-Line Rheo-Optical Investigation of the Dispersion of Organoclay in a Polymer Matrix during Twin-Screw Compounding

“…The mismatch in η 0 is thus to be assigned to the inherent precision of the in-line and off-line rheological measurements. Indeed, a precision of 10% for slit rheometry and rotational rheometry is generally admitted (see [ 34 ] and references therein).…”

Development of a system for monitoring performance in the strength and conditioning domain

“…Once the system configuration is complete, the user can record an exercise ( Record Exercise : BP2.3). The system zeroes the output levels on the force platforms to remove any associated drift of output levels with time that is an inherent feature of piezoelectric force transducers 15 ( Zero level : EA2.3.1), before commencing the recording ( Get data : EA2.3.2). Finally the system must store the data ( Store Data : BP2.4).…”

“…Signal Conditioning has been broken down into two EAs. The data must first be zeroed due to small continual drift of a piezoelectric output voltage under pressure 15 ( Remove offset : EA3.1.1) before a digital filter is applied ( Apply filter : EA3.1.2) to reduce the level of random noise within the signal. At this point, an exercise specific analysis is performed (BP3.2).…”

Editorial for Special Issue “Advances in Experimental and Computational Rheology”

“…The special issue "Advances in Experimental and Computational Rheology" joins fifteen works covering some of the latest advances in the fields of experimental and computational rheology applied to a diverse class of materials and processes, which can be grouped into four main topics: rheology [1][2][3][4][5], effect of process variables [6][7][8][9], rheometry and processing [10,11], and theoretical modeling [12][13][14][15] The characterization of rheological behavior is the main topic of five contributions, covering the following material systems: lubricating greases (Delgado et al [1]), Carbopol ® dispersion in water and in water/glycerol solutions (Varges et al [2]), natural hydraulic lime grouts (Baltazar et al [3]), fresh cement pastes (Rubio-Hernández [4]), and legume-protein-stabilized emulsions (Félix et al [5]).…”

“…Two of the special issue works are dedicated to rheometry and processing. Costa et al [10] assessed the employment of piezoelectric sensors on the acquisition of steady melt pressures in polymer extrusion, and Costanzo et al [11] evaluated the possibility of performing the linear and non-linear rheological characterization of samples with just a few milligrams.…”