A study of gelatin gelation by Fourier transform mechanical spectroscopy

Hawkins, Karl; Lawrence, Matthew; Williams, P. R.; Williams, R. L.

doi:10.1016/j.jnnfm.2007.05.016

Cited by 28 publications

(31 citation statements)

References 9 publications

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“…Weighted least squares fits of the data (spanning over more than four frequency decades) result in identical scaling exponents in G 0 ðxÞ / G 00 ðxÞ / x a with a ffi 0:71, thus confirming the attainment of the CG state. The value of a obtained using this approach is in excellent agreement with previous studies [42,44]. Moreover, values of G 0 ðxÞ and G 00 ðxÞ measured using the FTMS technique immediately prior to acquisition of the SR data are also shown in Fig.…”

Section: Resultssupporting

confidence: 89%

“…Low viscosity silicone oil was then added to the free surface of the sample to prevent evaporation before the temperature was lowered to the test temperature. An FTMS waveform [42] was employed to monitor gelation and upon attainment of frequency independent u (i.e., 63 ), an SR experiment (with a step strain of 10%) was performed. The mutation number [43] over the duration of the step-strain experiment was calculated to be 0.1, thus confirming the quasistable nature of the material at the GP under conditions of slow gelation [42,43].…”

Section: Methodsmentioning

confidence: 99%

“…An FTMS waveform [42] was employed to monitor gelation and upon attainment of frequency independent u (i.e., 63 ), an SR experiment (with a step strain of 10%) was performed. The mutation number [43] over the duration of the step-strain experiment was calculated to be 0.1, thus confirming the quasistable nature of the material at the GP under conditions of slow gelation [42,43]. The absence of sample inertia and slip artefacts was confirmed using standard techniques [48,49].…”

Section: Methodsmentioning

confidence: 99%

“…(11)] or equivalently, (ii) frequency independent loss tangent [tanðuÞ ¼ G 00 ðxÞ=G 0 ðxÞ] [42]. Hence, in systems undergoing gelation, identification of a CG state requires the viscoelastic properties of a material to be monitored as a function of both time and frequency.…”

Section: Aqueous Solution Of Gelatinmentioning

confidence: 99%

“…Hence, in systems undergoing gelation, identification of a CG state requires the viscoelastic properties of a material to be monitored as a function of both time and frequency. This has been successfully achieved for a range of gelling systems through the sequential application of (i) a series of oscillatory waveforms with discrete frequency (a frequency sweep approach), (ii) a multicomponent waveform (FTMS) [42][43][44], and (iii) a frequency modulated waveform [45,46]. In this work, FTMS was used to monitor the approach to the CG before a step-strain experiment was performed on the material at the CG state.…”

Section: Aqueous Solution Of Gelatinmentioning

confidence: 99%

See 4 more Smart Citations

i-Rheo: Measuring the materials' linear viscoelastic properties “in a step”!

Tassieri

Laurati

Curtis

et al. 2016

Journal of Rheology

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We present a simple new analytical method for educing the materials' linear viscoelastic properties, over the widest range of experimentally accessible frequencies, from a simple step-strain measurement, without the need of preconceived models nor the idealization of real measurements. This is achieved by evaluating the Fourier transforms of raw experimental data describing both the time-dependent stress and strain functions. The novel method has been implemented into an open access executable "i-Rheo," enabling its use to a broad scientific community. The effectiveness of the new rheological tool has been corroborated by direct comparison with conventional linear oscillatory measurements for a series of complex materials as diverse as a monodisperse linear polymer melt, a bimodal blend of linear polymer melts, an industrial styrene-butadiene rubber, an aqueous gelatin solution at the gel point and a highly concentrated suspension of colloidal particles. a)

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Section: Resultssupporting

confidence: 89%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Aqueous Solution Of Gelatinmentioning

confidence: 99%

Section: Aqueous Solution Of Gelatinmentioning

confidence: 99%

See 3 more Smart Citations

i-Rheo: Measuring the materials' linear viscoelastic properties “in a step”!

Tassieri

Laurati

Curtis

et al. 2016

Journal of Rheology

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show abstract

Gelation studies on acrylic acid‐based hydrogels via in situ photo‐crosslinking and rheology

Magami

Williams

2018

J of Applied Polymer Sci

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The gelation characteristics of acrylic acid (AA)‐based hydrogels were investigated using real time in situ photocrosslinking and rheological measurements. The gel point and gelation times were established using Winter–Chambon criteria. Frequency independence of tan δ was observed in all cases, such that G′ and G″ scaled as ∼ωn. The Flory–Stockmayer theory was used alongside other indices in order to probe the gelation and the post‐gelation characteristics of the critical gels and the fully formed hydrogels. Network relaxation exponents (n) were influenced by the concentrations of AA and methylene bis‐acrylamide. The gel stiffness (S) decreased with an increase in the concentration of the monomer and of the concentration of the crosslinker, while network branching decreased (lower fractal dimensions) at the gel point. The conversion at the gel point was found to be iso‐conversion with respect to the intensity of the UV irradiance used in the photocrosslinking reactions (1–20 mW/cm2). Thus, network clusters and the crosslinking reaction mechanism were the same irrespective of radiation intensity, although the rates of the reactions were affected. Having sufficient amounts of reactive species at the time of cure drive the crosslinking reactions beyond the gel point to greater crosslink density and smaller mesh sizes. The effects of auto‐acceleration and free‐volume were observed and shown to have key effects on the gelation mechanisms and the branching topographies of the network, when the concentration of the known polyacrylamide medium were not controlled. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46691.

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Roles of the molecular weight of n‐ethylene glycol diacrylates and UV irradiance on the mechanical properties at the gel point of acrylic acid based hydrogels

Magami

Williams

2019

J of Applied Polymer Sci

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We investigated sol-gel transitions in acrylic acid based hydrogels with real time in situ photocrosslinking and Fourier transform mechanical spectroscopy. Crosslinkable n-ethylene glycol diacrylate (EGDA) compounds with molecular weights (MWs) in the range 171-575 g/mol were used in standard solutions of known polyacrylamide. The mutation number (N mu ) was monitored in all of the experiments, such that N mu was 0.3 or lower at all of the experimental frequencies. During gelation, a frequency independence of tan δ was observed in all cases, such that the storage and loss moduli were scaled as about ω n ; this indicated the establishment of a sample spanning network in the hydrogels with the Winter-Chambon criteria. The relaxation exponents (ns) ranged from 0.35 to 0.81 when they were affected by both the MWs of the EGDAs and the UV irradiance. The stiffness of the critical gels steadily increased with increases in both the MWs of the EGDAs and the UV irradiance. The fractal dimensions decreased at the gel point with increasing MWs of the EGDAs, whereas it increased with an increase in the UV irradiance. An optimization tool (Design-Expert) was used to compare the effects and interactions of the reaction parameters on the gel-time characteristics of the critical gels and those of the fully formed hydrogels. A map (description) of the reaction parameters that can be used in the design of specific networks, particularly with values of n that are close to or equal to 0.5, is proposed.

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A study of gelatin gelation by Fourier transform mechanical spectroscopy

Cited by 28 publications

References 9 publications

i-Rheo: Measuring the materials' linear viscoelastic properties “in a step”!

i-Rheo: Measuring the materials' linear viscoelastic properties “in a step”!

Gelation studies on acrylic acid‐based hydrogels via in situ photo‐crosslinking and rheology

Roles of the molecular weight of n‐ethylene glycol diacrylates and UV irradiance on the mechanical properties at the gel point of acrylic acid based hydrogels

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