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Thermal, Thermo-mechanical, and Dielectric Characterization Tools for Polymers and Multicomponent Polymeric Systems
Published in Jose James, K.P. Pramoda, Sabu Thomas, Polymers and Multicomponent Polymeric Systems, 2019
Jose James, K.P. Pramoda, Sabu Thomas
The important applications of DMA characterization tool are as follows: It is the most sensitive method to determine Tg.It allows us to monitor the molecular transitions.It allows one to study cures.It allows us to study the viscoelastic properties of epoxy or polymer samples.It incorporates time–temperature superposition (TTS) for the prediction of the long-term behavior of a material.
Constitutive relations
Published in Roderic S. Lakes, Viscoelastic Solids, 2017
To experimentally determine if a material is thermorheologically simple, one may perform a set of creep or relaxation tests at different temperatures, and plot the results. If the various curves can be made to overlap by horizontal shifts on the log time axis, the material is considered thermorheologically simple. If the curves do not overlap, the material is not thermorheologically simple. The concept of time-temperature superposition has been of greatest use in polymers. Plazek [2.7.3] observes that given data within a fairly narrow experimental window (three decades or less) the test for thermorheological simplicity can only be definitive in its failure. The experiment is capable of demonstrating thermorheological complexity but it cannot demonstrate simplicity. The reason is that deviations can and do appear if the material is examined over a greater number of decades of time or frequency.
Linear and Non-Linear Rheological Properties of Foods
Published in Dennis R. Heldman, Daryl B. Lund, Cristina M. Sabliov, Handbook of Food Engineering, 2018
Ozlem C. Duvarci, Gamze Yazar, Hulya Dogan, Jozef L. Kokini
Some rheologically simple materials obey time temperature superposition principles where time and temperature changes are equivalent (Ferry, 1980). Frequency data at different temperatures are superimposed by simultaneous horizontal and vertical shifting at a reference temperature. The resulting curve is called a master curve, which is used to reduce data obtained at various temperatures to one general curve, as shown in Figure 1.12. The time-temperature superposition technique allows an estimation of rheological properties over many decades of time.
Changes in the rheological characteristics of asphalt binders modified with soybean-derived materials
Published in International Journal of Pavement Engineering, 2021
Muhammad Akhtar Tarar, Ammad Hassan Khan, Zia ur Rehman, Aasim Inam
A frequency sweep test was conducted on unmodified and SDM modified asphalt binders in unaged, RTFO and PAV conditions. The frequency sweep covered the range of frequencies from 0.1 to 100 rad/s using a DSR with plate geometry 8-mm and gap 2-mm at test temperatures of 6, 12°C, 18°C, 24°C, 30°C and 36°C using 1% controlled strain. The reference temperature was selected as 18°C. The shift factors were calculated and used to shift the modulus values at different temperatures, horizontally to construct a master curve at the reference temperature. Time temperature superposition is an important source for shifting data from different temperatures to the reference temperature (Dealy and Plazek 2009). The WLF equation is considered a good approach to construct shift factors (Yusoff et al. 2011, Shangguan et al. 2017).
Cohesive zone fracture modelling of asphalt pavements with applications to design of high-performance asphalt overlays
Published in International Journal of Pavement Engineering, 2018
The bulk behaviour of asphalt concrete at low temperatures is viscoelastic. Viscoelastic materials have time dependent material properties. Use of viscoelastic material model for asphalt concrete material is very important to obtain reliable results from computer simulations. In the current work, a generalized Maxwell model was used to represent relaxation modulus of asphalt concrete. The relaxation moduli were obtained from creep tests following AASHTO T 322-07 specifications for indirect tensile creep and strength tests. As per this method, creep tests are performed at three temperatures for 1000-s durations, which allows for development of a material master curve. Based on testing at different temperatures, a time–temperature superposition principle is also established to account for variation in material properties at different temperatures. The functional form of generalized Maxwell model is given as following:
Viscoelastic characterisation of warm asphalt mixtures
Published in Australian Journal of Civil Engineering, 2023
Natália Guterres Mensch, Lélio Antônio Teixeira Brito, Luiza Carbunck Godoi, Kethelin E. Klagenberg Beckert, Felipe Do Canto Pivetta, Jorge Augusto Pereira Ceratti
For the formation of the master curve, the Williams, Landel and Ferry (WLF) principle was used as a time-temperature superposition model at the reference temperature of 21°C. As a model for adjusting the points of the master curve for the dynamic modulus, a sigmoidal adjustment (Equation 1) was applied, using Microsoft Office Excel’s Solver tool minimising sum of quadratic errors, following the recommendations of Yusoff, Chailleux, and Airey (2011). The phase angle master curve was adjusted to a sixth-degree polynomial.