Fourier Transform Rheology: A New Tool to Characterize Material Properties

Grosso, Massimiliano; Maffettone, Pier Luca

doi:10.5772/15725

Cited by 4 publications

(3 citation statements)

References 32 publications

(32 reference statements)

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“…(Figure 1). The nonlinear response of each complex material results in a unique Fourier transform spectrum consisting of peak intensities at odd harmonics which allows the characterization of nonlinear rheology of various viscoelastic systems like emulsions (Reinheimer et al, 2012), immiscible polymer blends (Carotenuto et al, 2008;Grosso & Luca, 2011), linear and branched polymers melts (Hyun et al, 2007). The Fourier transform rheology (FTR) technique can be used to determine nonlinear rheological properties of metastable systems-dispersed gas-liquid (foam), or liquid-liquid (emulsions W/O and O/W) (Reinheimer et al, 2011) and polymer melts, polymer solutions, and polymer blends (Hyun et al, 2006a;Hyun & Wilhelm, 2009).…”

Section: Fourier Transform Rheologymentioning

confidence: 99%

Advances in large amplitude oscillatory shear Rheology of food materials

Erturk

Kokini

2023

Front. Food. Sci. Technol.

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Molecular interactions determine the microstructure of food, as well as its response to deformation and flow. In order to design efficient processing equipment, to produce high-quality, stable end products, to predict textural and sensory properties, and to ensure consumer acceptance, the characterization of food rheology is essential. Deformations are rapid and large during the processing of foods and during consumption. In food studies, large amplitude oscillatory shear (LAOS) has become increasingly popular due to its ability to mimic real-life processes. When food is subjected to dynamic oscillatory shear tests, a sinusoidal deformation is applied, the mechanical stress (or strain) is probed, and the response is recorded. This chapter summarize main methods to extract meaningful rheological parameters from complex LAOS response of selected food materials. A time-resolved nonlinear rheology method, sequence of physical processes (SPP), gave detailed interpretations of transient microstructures, whereas the Fourier Transform coupled with Chebyshev decomposition (FTC) method provide static measurements at specific strains. LAOS behavior and its relationship to food microstructures and texture still needed to be studied in depth. By constructing more accurate mechanical models of complex food systems, the fundamental knowledge can be applied to evaluate the nonlinear rheology of food for consumer acceptance and efficient processing.

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Section: Fourier Transform Rheologymentioning

confidence: 99%

Advances in large amplitude oscillatory shear Rheology of food materials

Erturk

Kokini

2023

Front. Food. Sci. Technol.

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“…If a blend has a composition in which one polymer dominates by volume fraction and/or by its low viscosity, it can act as a continuous phase (matrix) separating the other polymer(s) into distinguishable particles. The processing conditions largely affect the final blend morphology and may give rise to a droplet-shaped, a fibrillated, a laminar, and/or a cocontinuous morphology [1,11,[15][16][17][18]. Which of these morphologies will dominate depends on the flow behavior during processing and the shear stresses, which play a part in the breakup or coalescence of the dispersed phase.…”

Section: Introductionmentioning

confidence: 99%

Macromolecular Insights into the Altered Mechanical Deformation Mechanisms of Non-Polyolefin Contaminated Polyolefins

et al. 2022

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Current recycling technologies rarely achieve 100% pure plastic fractions from a single polymer type. Often, sorted bales marked as containing a single polymer type in fact contain small amounts of other polymers as contaminants. Inevitably, this will affect the properties of the recycled plastic. This work focuses on understanding the changes in tensile deformation mechanism and the related mechanical properties of the four dominant types of polyolefin (PO) (linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP)), contaminated with three different non-polyolefin (NPO) polymers (polyamide-6 (PA-6), polyethylene terephthalate (PET), and polystyrene (PS)). Under the locally elevated stress state induced by the NPO phase, the weak interfacial adhesion typically provokes decohesion. The resulting microvoids, in turn, initiate shear yielding of the PO matrix. LLDPE, due to the linear structure and intercrystalline links, is well able to maintain high ductility when contaminated. LDPE shows deformation similar to the pure material, but with decreasing ductility as the amount of NPO increases. Addition of 20 wt% PA-6, PET, and PS causes a drop in strain at break of 79%, 63%, and 84%, respectively. The typical ductile necking of the high-crystalline HDPE and PP is strongly disturbed by the NPO phase, with a transition even to full brittle failure at high NPO concentration.

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“…On the other hand, the value of γ0 after which G' and G" start to vary (they both often decrease) corresponds to the critical point after that the material response is beyond the linear viscoelastic regime (i.e., non-linear viscoelastic regime). As a consequence, the shear stress response σ(t) is no longer a simple sine wave but rather a sinusoidal function consisting of higher harmonics (Grosso & Maffettone 2011). Although SAOS are experiments are relatively easy to perform, they can still be problematic if a well-defined experimental protocol is not applied.…”

Section: Small Amplitude Oscillatory Shear Deformationsmentioning

confidence: 99%

Linear and non-linear rheology of heterogeneous polymeric systems

Dessi¹

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Since more than one hundred years ago the discovery of polymerization mechanisms that allowed obtaining polymeric systems with precise and complex molecular structures has fascinated scientists from all over the world and dramatically changed the concept of industry production and our daily life. The reason why industrial polymers have got such great attention in many different scientific and technological applications is the existence of an intimate relationship between their molecular structure and rheological properties with final processing and mechanical properties. As a result, industrial standard methods were intensively developed which most of them allow to obtain easily and quickly important structural and mechanical information for the final application to which the material is intended. However, some technical issues may not be properly taken into account given a wrong characterization of the material. One of the most common industrial dynamic mechanical test employed in order to characterize the rheological response involve torsion deformations. Torsion measurements are in general performed on stiff and elastic materials, such as non-filled and filled vulcanized rubbers, in order to overcome instrument compliance issues and/or wall slip phenomena between the sample and the testing geometry that may importantly affect the measurement itself. In the first part of this work we clearly show that large departures of the rubbery modulus for industrial elastomers may occur when dynamic mechanical measurements are performed in torsion according to industrial standards. The testing sample was chosen in such a way that a comparison with the most common and reliable rheological protocol, small amplitude oscillatory shear, was possible. Once compliance issue and other possible sources of errors were addressed, experimental results in dynamic torsion measurements were found to depend on specimen geometry and its aspect ratios, and the sample loading by clamping. However, so far the empirical corrections proposed do not completely fulfilled the experimental artefact. This observation made this work necessary to establish a better guideline that allows more reliable torsion dynamic mechanical measurements in industrial standard protocols. One of the class of polymer materials that obtain extensive application in the technology field (in particular rubber technology) is represented by the category of filled polymers. It is well-known that the addition of fillers into a polymer matrix generates mechanical reinforcement in the resulting polymer compound. However, the reinforcement mechanism still remains in debate since it does strongly depend on the specific chemistry and properties resulting from polymer-particle interactions. More specifically, the role of the presence of a bound polymer layer on particle surface is not completely addressed. One strategy in order to investigate the reinforcement mechanism is to study the rheological response of favorably interacting filled polymer systems. The second part of this work, hence, is focused on a better understanding of the polymer-particle flow dynamics in nanofilled model polymers for which the presence of bound polymer layers was not always possible to assess. Surprisingly, rheological results show a clear transition from polymer dominated dynamics into “glassy” network dynamics leading to a percolated behavior. These findings encouraged us to further investigate the nature of the polymer-particle interactions in the percolated structure that was found to be most likely related to the presence of hydrogen bonds. Another peculiar feature of the mechanical behavior shown from polymer systems is the capability to be deformed to large amplitude deformations without losing their macroscopical shape. Often large deformations are oscillatory and industrial rubbers widely fulfill this characteristic. Despite mechanical properties in large deformations of polymer network have been observed and investigated for more than six decades, addressing a proper physical model description to the material response remains a challenge. The last part of this work took up the chance to develop a new continuum model that for the first time can describe, at least qualitatively and partially quantitatively, the experimental asymmetric hysteresis response of filled industrial rubbers when they are subjected to large amplitude oscillatory deformations in uniaxial extension superimposed to a steady one.

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Fourier Transform Rheology: A New Tool to Characterize Material Properties

Cited by 4 publications

References 32 publications

Advances in large amplitude oscillatory shear Rheology of food materials

Advances in large amplitude oscillatory shear Rheology of food materials

Macromolecular Insights into the Altered Mechanical Deformation Mechanisms of Non-Polyolefin Contaminated Polyolefins

Linear and non-linear rheology of heterogeneous polymeric systems

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