Temperature modulated optical refractometry: A novel and practical approach on curing and thermal transitions characterizations of epoxy resins

Santos, Demétrio Jackson dos; Gouveia, Júlia Rocha; Philipp, Martine; Augusto, Aline Cristina; Ito, Nathalie Minako; Krüger, Jan

doi:10.1016/j.polymertesting.2019.105915

Cited by 11 publications

(15 citation statements)

References 11 publications

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“…This quantity can be assumed as constant, once the optical dipole moments depend only weakly on temperature. However, for temperature dependent measurements, small temperature changes (i.e., low temperature rate) must be assured, in order to better fulfill the condition r = constant [16]. As stated in Equation (1), the changes of n due to temperature and/or time mirrors the changes of mass density and, consequently, the volume.…”

Section: Introductionmentioning

confidence: 99%

“…T(t)= trueT¯+ ATsin(2πft)n(t)= NMEAN+ Ansin(2πft− ϕ) where t refers to time, T¯ is the reference temperature, AT is the temperature amplitude (perturbation), and f is the frequency of modulation. With respect to Equation (4), NMEAN represents the average response, and its calculated using a moving average over one modulation period [16] and obtained from TMOR software. An is the amplitude of the refractive index, and ϕ is the phase shift between the temperature modulation and the refractive index response.…”

Section: Introductionmentioning

confidence: 99%

“…For more information regarding TMOR, the reader is referred to ref. [15,16]:β′(f,trueT¯)=6truen¯(T¯)An(f,trueT¯)cos(ϕ(f,trueT¯))AT(n¯2(T¯)+2)(n¯2(T¯)−1)β″(f,trueT¯)=6truen¯(T¯)An(f,trueT¯)sin(ϕ(f,trueT¯))AT(n¯2(T¯)+2)(n¯2(T¯…”

Section: Introductionmentioning

confidence: 99%

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Thermal Transitions of Cocoa Butter: A Novel Characterization Method by Temperature Modulation

Gouveia

Lixandrão

Tavares

et al. 2019

Foods

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For the first time, the novel experimental technique Temperature Modulated Optical Refractometry (TMOR) was employed for cocoa butter thermal transitions characterization. The average refractive index (NMEAN), the volume (v) change, and the volumetric expansion coefficient (βq) as well as the dynamic quantities β′ and β″ (real and imaginary volumetric expansion coefficient, respectively) were monitored during cooling and heating and compared to the heat flow curves obtained via the standard technique dynamic scanning calorimetry (DSC). The investigation of these quantities showed that TMOR analysis can yield not only thermal transitions temperatures that are comparable to DSC results, but also some new thermal events that are not detected by DSC. This outcome suggests that TMOR might provide some additional insights on cocoa butter melting and crystallization by means of frequency-dependent measurements due to temperature modulation. This new information that can be accessed during temperature ramps might provide a deeper insight into thermal behavior of fat-based foods, evidencing TMOR value as a tool for thermal transitions investigation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermal Transitions of Cocoa Butter: A Novel Characterization Method by Temperature Modulation

Gouveia

Lixandrão

Tavares

et al. 2019

Foods

Self Cite

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“…where T(t) is the instantaneous temperature, T is the average temperature, A T is the modulation amplitude, and f is the modulation frequency. The small temperature perturbation described in Equation ( 4) induces a refractive index response which naturally follows the same sinusoidal profile, but with a phase shift between both signals, as presented in Equation ( 5) [38].…”

Section: Temperature Modulated Optical Refractometry (Tmor)mentioning

confidence: 99%

Epoxidation of Kraft Lignin as a Tool for Improving the Mechanical Properties of Epoxy Adhesive

et al. 2020

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Owing to its chemical structure, wide availability and renewable nature, lignin is a promising candidate for the partial replacement of fossil-based raw material in the synthesis of epoxy resins. Its poor compatibility has been reported to be one of the main drawbacks in this domain. On the other hand, a well-established modification method for lignin epoxidation has been used for many years for the improvement of lignin compatibility. However, the extent of the effect of lignin epoxidation on the improvement of bio-based epoxy mechanical properties, applied as adhesives, is still an open question in the literature. In this context, a pristine and industrial grade kraft lignin (AKL) was reacted with epichlorohydrin to yield epoxidized lignin (E-AKL) in this work. Afterwards, AKL or E-AKL were separately blended with petroleum-based epoxy resin at 15 and 30 wt% and cured with a commercial amine. The adhesive curing kinetic was evaluated using a novel technique for thermal transition characterization, Temperature Modulated Optical Refractometry (TMOR); the results showed that the incorporation of AKL reduces the crosslinking rate, and that this effect is overcome by lignin modification. Mechanical tests revealed an improvement of impact and practical adhesion strength for samples containing 15 wt% of E-AKL. These results elucidate the effect of lignin epoxidation on the application of lignin-based epoxy adhesives, and might support the further development and application of these bio-based materials.

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“…In order to properly assess the effect of the filler on the resin, it is necessary to know thoroughly the crosslinking process of the neat resin [35][36][37][38][39][40][41][42]. In particular, it is advisable to determine the effect of heat treatment on the resin properties [43][44][45][46].…”

Section: Wpływ Wygrzewania Na Sieciowanie żYwicy Epoksydowej Przeznacmentioning

confidence: 99%

The effect of the heat treatment on the crosslinking of epoxy resin for aviation applications

Mucha¹,

Sterzyński

Krzyżak³

2020

Polimery

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We have investigated the MGS L285 epoxy laminating resin system, used in aviation applications. A number of tests were carried out, namely Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC), tensile testing, three-point bending flexural testing, Charpy impact testing, Shore D hardness, density measurements and Fourier-Transform Infrared spectroscopy (FT-IR). Moreover, the tensile toughness U TT , the brittleness B and the linear isobaric thermal expansivity α L were calculated. The samples were subjected to heat treatment in the temperatures of 50, 60 and 80°C for 15 hours or were stored in room temperature. Glass transition temperature, hardness, density as well as other properties were observed to rise along with the increasing heat treatment temperature, suggesting the validity of applications of Voronoi-Delaunay structural analysis to polymer science. On the other hand, properties such as brittleness, toughness and impact strength exhibited a non-linear course of changes as a function of the heating temperature.

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Temperature modulated optical refractometry: A novel and practical approach on curing and thermal transitions characterizations of epoxy resins

Cited by 11 publications

References 11 publications

Thermal Transitions of Cocoa Butter: A Novel Characterization Method by Temperature Modulation

Thermal Transitions of Cocoa Butter: A Novel Characterization Method by Temperature Modulation

Epoxidation of Kraft Lignin as a Tool for Improving the Mechanical Properties of Epoxy Adhesive

The effect of the heat treatment on the crosslinking of epoxy resin for aviation applications

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