This page details some of the milestones in the development of rheometers over the decades. As technology developed, so did rheometers, becoming the powerful analytical tools they are today.
The development of the rheometer business since 1980
In the 1980s, using computers and software became more and more popular. This development also made it possible to start conducting measurements and tests digitally. Instruments could be controlled with the help of digital systems. Moreover, data such as software could be stored on data cassettes that used magnetic recording tapes. Having the option to store data digitally for longer periods of time was a major novelty much appreciated by various industries, including rheometry. For example, Haake started using data cassettes in 1978 and Rheometrics in 1982. With the help of a D/A-A/D data converter (digital to analogue and vice versa) by Haake, introduced in 1986, computers could control viscometers. In 1984, Brookfield introduced viscometers with microprocessor-controlled keyboards. In these early stages of digitalized measuring, instruments were connected to computers with special interface controllers as separate modular units. Haake, for example, introduced the Rheocontroller RC to be used with the HP 85, Contraves brought the Rheoconverter for the HP 9815 as well as the Rheoanalyzer RA, which was IBM-compatible, on the market, whereas Physica (later Anton Paar) presented the System Interface SI.
The first DIN standard
In 1980, the DIN measuring system (DIN 53019), a DIN standard on concentric cylinder geometries with a narrow gap, was put forward. In the same year, Wolfgang Geissle presented the 1st and 2nd “mirror relations”, suggesting that curve functions following each other usually have similar shapes. The shear rate and the time are presented on the x-axis. The mirror axis is positioned at a right angle to the x-axis.[1,2,3,4]
a) the steady-state shear viscosity ƞ( ) and the transient shear viscosity ƞ+( , t),
b) the steady-state 1st normal stress coefficient Ψ1( ) and the transient 1st normal stress coefficient Ψ1+( , t)
The first home computers
1980 was also the year Apple and Commodore brought the first home computers onto the market. To explain this development in a little more detail, this is a very brief summary of the steps that lead to the launch of the home computer and personal computer being a success:
- The first integrated circuits (IC) were already brought onto the market by Jack Kilby in 1959 and later on by Robert Noyce in 1961.
- In 1967, Texas Instruments brought out their first hand-held calculator.
- Only a few years later, in 1971, Intel and M. Hoff, F. Faggin, S. Mazor, and M. Shima introduced a single-chip microprocessor.
- Hewlett-Packard then followed in the footsteps of Texas Instruments and brought out its own pocket calculator in 1974.
- In the following year, Steve Wozniak and Steve Jobs launched a computer onto the market that had both a display and a keyboard. This computer is the predecessor of the first computers sold later by Apple.
- In 1981, IBM launched the PC, the Personal Computer.
- The computer introduced by Bill Gates and Microsoft used the MS-DOS system, which is a disk organization system.
- Intel brought out circuits at around the same time.
- In 1983, the mouse was introduced.
As a result of all these technological advances, IBM gained influence in controlling rheometers in industrial labs, allowing for users to navigate those instruments by using software.
Technological changes at laboratories
Around the same time, technology was also changing the way people worked in laboratories. In 1981, the first speed-controlled viscometer, brought onto the market by Contraves, was the first to have an integrated microprocessor. This new add-on made it possible to measure torque values as a function of the power consumption of the electric drive. In the same year, Rheometrics presented the so-called “force re-balance transducer”. This transducer was meant to compensate the deflection of the torsion element, which is a mechanical torque sensor. The aim was for it to perform tests with zero deflection.
In 1982, various industries started using UV-curing adhesives. Also in this year, a DIN standard on double-gap cylinder measuring geometries, DIN 54453, was published and redrawn in 2004. In 2019, this was replaced by ISO 3219-2.
Only a year later, in 1983, Carrimed introduced its first rheometer of the type CS 50. The instrument was a controlled stress device with an air bearing and an asynchronous drive. This rheometer could be controlled with the help of an Apple microcomputer.
Changes to viscometers, terms, and models
The year 1985 was significant in terms of further developments in the field. Howard A. Barnes and Ken Walters questioned the term “yield point”. They suggested that yield points do not exist, claiming that they can only be detected because the instruments used to measure them show limited angle resolution. Thus, the term was changed to “yield stress”.[5, 6] H. Giesekus and R.B. Bird introduced models of non-linear deformation behavior. Physica introduced their first rotational viscometer, which was of the type Viscolab LC. This viscometer was equipped with a DC motor, which was a novel add-on that allowed speed tests. In this year the application of adhesives was automatized in automotive production with the help of robots.
Moreover, in 1985 superabsorbent polymers were produced industrially for the first time. For example, Procter & Gamble used them for its Pampers diapers. Those superabsorbers are, in fact, polyacrylates that appear in the form of small polymer grains. Their size is between 0.1 mm and 0.8 mm and they swell when absorbing fluids. These polymers absorb fluids up to the 1000-fold of their dead weight even under pressure as polyelectrolytes. They are used in diapers, for fire extinguishers containing hydrogel-polymers, for food packaging, and for cable sheathing, etc. [18,19]
In the following year, M. Doi and S.F. Edwards introduced an enhanced reputation model. The aim of this model was to describe the motion of uncrosslinked polymer molecules. 1986 was also the year when Hans-Martin Laun claimed that 2 · G’(ω) = N1(γ) for γ = ω → 0. He thus suggested that at the same low values of ω (from oscillation/frequency tests) and γ (from rotation/flow curves) twice the value of G’ corresponds to the value of the 1st normal stress difference N1. In terms of technological developments, Bohlin put forth a controlled-stress rheometer of the type CS 10. This rheometer came with an air bearing and an asynchronous drive. Finally, in 1986 IBM launched their first laptop, which weighed 5.4 kg.
Developments in the automotive industry – and more advanced geometries
1987 was a significant year for the automotive industry. Akzo (for Audi) and Herberts introduced water-based (WB) coatings that consisted of a significantly reduced percentage of solvent and were meant to be used as base coats for an original equipment manufacturer (OEM) automotive serial coating process. 1988 was the year when the motion of uncrosslinked polymer molecules was discussed by J. Des Cloizeau, who presented his Double-Reptation Model, whereas 1989 will be remembered in rheometry circles because N.W. Tschoegl presented a calculation program for data conversion and also J. Honerkamp and J. Weese introduced a software program for data conversion. [9,10,11,12,13]
In the beginning of the 1990s, the ISO 3219 standard on the measuring geometries of concentric cylinders (CC) and cone-and-plate (CP) geometries was published. In testing, the preset now suggested to select defined shear rates instead of rotational speeds. Much later, in 2019, ISO 3219-2 was published. In the same year, Dietmar Schulze introduced his Ring Shear Device. This device was intended to be used for powders as well as solid bulk materials. With the help of the Ring Shear Device a rotational measurement at a constant and low shear rate can be performed.[20,21,22]
The dawn of the internet age – plus new rheometers
In 1991, CERN introduced the World Wide Web to the public and the following year brought great developments in the research of asphalt and road construction. Due to a request from The Federal Highway Administration (FHA), the American Association of State Highway and Transportation Officials (AASHTO) launched the Strategic Highway Research Program (SHRP). The main aim of this project was to find out how to extend the working life of road surfaces without affecting their performance. In this context, research focused on the viscoelastic behavior of binding agents that are used in asphalt for road construction. One such binding agent is polymer-modified bitumen (PmB) that has been used since the 1980s. In order to obtain results, it was recommended to conduct oscillatory tests using a Dynamic Shear Rheometer (DSR), SHRP tests, and ASTM D7175.
In 1992, Haake and Reologica both introduced controlled-stress rheometers. While Haake’s rheometer was of type RheoStress RS 100 and had an automatic lift system, air bearing, and an asynchronous drive, Reologica’s instrument was of type StressTech and had an air bearing and an asynchronous drive. (Later on, in 2010, Reologica stopped producing rheometers).
The first digitally controlled rheometer (of type UDS 200) was introduced in 1995 by Physica (now Anton Paar). The rheometer had an air bearing, an electronically commutated (EC) synchronous drive with digital control of the torque, and digital control of deflection angles and speeds. In 1996, Thermo Electron Corporation acquired Haake, which first became Thermo Haake and then Thermo. Since 2007, Thermo Scientific has been part of Thermo Fisher, which sells Haake rheometers to this day. Shortly after, Herberts introduced powder coatings as clear coats for OEM automotive serial coating. The prerequisites for this development to occur were introduced in 1995 and 1996, when powder coats were launched as fillers and as clear coats in the form of powder slurries by BASF Coatings.
In 1999, Anton Paar launched the MCR xx0 rheometer series. In the same year, Stefan Hell introduced STED Microscopy (stimulated demission depletion). The resolution of images was then much better than it used to be.
The turn of the millennium brings automation – and new coatings
Ever since the early 2000s, the automotive industry has been using UPE fillers (unsaturated polyesters), WPs (wash primers), WB (water-based) base coats, 2c PU (two-component polyurethanes) or EP (epoxy) fillers, and 2c PU clear coats as high-solids coats containing only small amounts of solvents for repair coats. In 2000, robots in combination with rheometers by BASF made automatic sampling and cleaning of the measuring geometries possible. Much later, Bosch Lab Systems introduced a system entirely controlled by robots, meaning that both the rheometer and the robot were controlled by the same system. One year later, Anton Paar introduced the High-Throughput Rheometer (of type HTR) as a completely integrated system.
In 2002, TA Instruments bought Rheometrics. In 2003, organically modified silanes, consisting of an inorganic sol/gel component and an organic polymer, were made available and used, for example, in the automotive industry. Their hybrid character is the reason why they are used as functional coatings, for example as scratch-proof automotive clear coatings. [14, 15, 16] In this year Malvern Instruments bought Bohlin. Malvern remained part of Spectris and continued to sell Bohlin rheometers.
Physica becomes Anton Paar
2004 was a significant year for Anton Paar. Physica changed its name to Anton Paar Germany. Anton Paar Germany had been part of Anton Paar ever since 1996 and continued to sell Physica rheometers. In 2004, Anton Paar introduced the MCR xx1 series as well as the TruGap option, allowing automated control or adjustment of the gap dimension in parallel-plate as well as cone-and-plate measuring geometries.
In 2010, two standards for application-related rheological testing when using oscillatory rheometers were released. DIN 51810-2 (yield point and flow point of lubricating greases) as well as DIN 54458 (viscoelastic adhesives particularly regarding the physical stability and stringiness) were published. 2010 was also the year when 3D printers saw increased use in industrial serial production. Due to the possibility of using a wide array of materials as “printing ink”, very complex structures can be built with the help of these printers. Materials such as polymers, rubber, ceramics, gypsum, glass, metals (e.g. stainless steel, copper, titanium, bronze), dry powders, wet dispersions, biological tissue, bones, cartilage, and even stem cells can be used in generative or additive manufacturing made possible by 3D printers. Alongside 3D printing becoming more and more popular, the production of polymers from biological sources was a new trend at this time. For example, Lanxess introduced EPDM rubber (ethylene propylene diene monomer rubber) that is made from bio-based ethylene which again is made from Brazilian sugarcane.[23, 18]
Before the turn of the decade, Stefan Hell introduced the Miniflux Fluorescence Microscope, which was able to show a resolution of 1 nm (which is assumed to be the approximate distance between molecules). The microscope can be used for biophysical applications, e.g. when examining living cells or proteins.
Two drive units in one rheometer
The second decade of the 2000s brought several developments and great success in the development of the rheometer. The MCR xx2 series was launched by Anton Paar in 2011. In 2013, Anton Paar introduced the Modular Compact Rheometer MCR 702 TwinDrive . For the first time in the history of rheology, this instrument allowed rheological examinations with two simultaneous torque transducers and two drive units. Only a few years later, in 2016, the Anton Paar MCR x2 series maked it possible to light samples during the measurement.
In 2018, the microprocessor (MP) technology and the speed of data processing were the focus of discussion within the field of rheology. In 2019, ISO standard 3219 was published in a revised form. Rotational and oscillatory rheometry are addressed in part one, which focuses on general terms and definitions. Parts 2 and 3 were revised. In terms of launches, Anton Paar launched the MultiDrive technology with a linear drive, allowing for the rheometer to conduct Dynamic Mechanical Analysis.
In early 2020, Malvern Panalytical Limited announced that it will end the production and distribution of their Kinexus rotational rheometers and Rosand capillary rheometers, which were taken over by NETZSCH Analyzing & Testing. In the same year, TA Instruments presented the facelift of their DHR series called DHR 10 to 30.
The world of rheometry has changed considerably in the four decades since 1980. As technology has advanced, rheometers have kept pace with the new developments, increasing their value and becoming indispensable tools in the characterization of materials.
1 Gleissle, W. (1980). Two simple time-shear rate relations combining viscosity and first normal stress coefficient in the linear and non-linear flow range, ed. G. Astarita, G. Marucci, L. Nicolais, Proc. 8th Internat. Congr. Rheol. in Naples, Plenum Press
2 Läuger, J.; Huck, S. (2000). Real controlled stress and controlled strain experiments with the same rheometer, Proc. 8th Int. Congr. Rheol., Cambridge, 2000; Läuger, J.; Bernzen, M. (2000, 2001). “Getting the zero-shear viscosity of polymer melts with different rheological tests”, Ann Trans Nordic Rheol Soc 8/9; Läuger, J.; Wollny, K.; Huck, S. (2002). Direct strain oscillation − a new method enabling measurements at very small shear stresses and strains, Rheol. Acta; Läuger, J.; Wollny, K.; Stettin, H.; Huck, S. (2004). “A new device for the full rheological characterization of magneto-rheological fluids”, Int. J. Mod. Phys. B 19; Läuger, J.; Heyer, P. (2007). “Validation of empirical rules for a standard polymer solution by different rheological tests”, Ann Trans Nordic Rheol Soc 15; Läuger, J.; Heyer, P. (2009), Interfacial shear rheology of coffee, Proc 5th Int. Symp. Food Rheology & Structure ISFRS, Zürich; Läuger, J.; Stettin, H. (2010). “Differences between stress and strain control in the non-linear behavior of complex fluids (LAOS)”, Rheol. Acta, Springer
3 Laun, H.M. (1986). “Prediction of elastic strains of polymer melts in shear and elongation”, J. Rheol.; Laun, H.M.; Schmidt, G.; Gabriel, C.; Kieburg, C. (2008). “Reliable plate-plate magnetorheometry based on validated radial magnetic flux density profile simulations”. Rheol Acta, Springer
4 Pahl, M.; Gleissle, W.; Laun, H.-M. (1995). Praktische Rheologie der Kunststoffe und Elastomere, VDI, Düsseldorf
5 Barnes, H.A.; Walters, K. (1985). “The yield stress myth?”, Rheol. Acta; Barnes, H.A.; Hutton, J.F.; Walters, K. (1989). An introduction to rheology, Elsevier: Amsterdam; Barnes, H.A.; Schimansky, H.; Bell, D. (1999). “30 years of progress in viscometers and rheometers”, J. Appl. Rheol.; Barnes, H.A. (2000). A handbook of elementary rheology, Univ. of Wales Inst. Non-Newtonian Fluid Mechanics: Aberystwyth; Barnes, H.A.; Bell, D. (2003). “Controlled-stress rotational rheometry − a historical review”, Korea-Australia Rheol. J; Barnes, H.A (2007). “The ‘yield stress myth’ paper – 21 years on”, J. Appl. Rheol. 17
6 Macosko, C.W. (1994). Rheology − principles, measurements and applications, Wiley-VCH, New York
7 Giesekus, H. (1994). “Die Elastizität von Flüssigkeiten”, Rheol. Acta, Phänomenologische Rheologie, Springer, Berlin
8 Doi, M.; Edwards, S.F. (1986). Theory of polymer dynamics, Clarendon, Oxford; Doi, M. (1996). Introduction to polymer physics, Clarendon, Oxford
9 Clariant, documentation (2006): 150 Jahre Forschung und Entwicklung in der Chemie
10 Dohnke, K. (2000). Die Lack Story − 100 Jahre, Verb. d. Lackindustrie (ed.), Dölling, Hamburg
11 Des Cloizeaux, J. (1988). Europhys. Lett.
12 Tschoegl, N.W. (1989). The phenomenological theory of linear viscoelastic behavior, Springer, New York
13 Honerkamp, J.; Weese, J. (1993). “A nonlinear regularization method for the calculation of relaxation spectra”, Rheol. Acta
14 Brock, T.; Groteklaes, M.; Mischke, P. (2009). Lehrbuch der Lacktechnologie, Vincentz, Hannover, (3rd ed.); Brock, T. (2008). “Wie wird in Zukunft lackiert – Trends und Perspektiven”, Aktuelles z. Chemie d. Farben u. Lacke, Reihe High Chem hautnah, Bd 3, GDCh, Frankfurt/M
15 Maleika, R.; Nennemann, A.; Pyrlik, O. (2008). “Sol-Gel-Beschichtungen und Hybridsysteme”, Aktuelles z. Chemie d. Farben u. Lacke, Reihe High Chem hautnah, vol. 3, GDCh, Frankfurt/M
16 Sepeur, S.; Laryea, N.; Goedicke, S.; Groß, F. (2008). Nanotechnologie – Grundlagen und Anwendungen, Vincentz, Hannover
17 Meyer, O.E. (1861/1863). Über die Reibung in Flüssigkeiten, J. de Crelle; Meyer, O.E. (1874). Theorie der elastischen Nachwirkung, Pogg. Ann. Physik; Neumann, F.; Meyer, O.E. (1855). Vorlesungen über die Theorie der Elasticität der festen Körper und des Lichtäthers, Teubner, Leipzig
18 Patton, T.C. (1987). Paint flow and pigment dispersion, Wiley, New York, (2nd ed.)
19 PCI (Powder Coating Institute), North America, information, www, 2005
20 Ostwald, Wo. (jun.) (1907). Zur Systematik der Kolloide, Koll. Z.; Über die Geschwindigkeitsfunktion der Viskosität disperser Systeme (1925), ibid.; Ostwald, W.; Auerbach, R. (1936). Über die Viskosität kolloider Lösungen im Struktur-, Laminar- und Turbulenzgebiet, ibid.
21 Outlast Technologies Inc., product information “Thermocules”, www, 2009
22 Pahl, M.; Gleissle, W.; Laun, H.-M. (1995). Praktische Rheologie der Kunststoffe und Elastomere, VDI, Düsseldorf
23 Monk, C.H.J. (1958). A rotary viscometer for thinning paint samples, JOCCA; Routine measurement of the viscosity of paint samples (1966), ibid.
24 Popplow, M. (2004). Die Emanzipation der Technik, J. Spektr. d. Wiss. Spezial “Renaissance”
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