Polymerization-induced shrinkage and dynamic thermal expansion behavior during network formation of polyurethanes

Philipp, Martine; Zimmer, Bettina; Ostermeyer, Martin; Krüger, Jan

doi:10.1016/j.tca.2019.01.012

Cited by 15 publications

(12 citation statements)

References 26 publications

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“…The novel-experimental technique Temperature Modulated Optical Refractometry (TMOR) emerges as a promising approach to monitor condensed matter behavior and phase transitions under a controlled temperature program [14]. Developed by Anton Paar OptoTec in cooperation with the group of Dr. Krüger, TMOR identifies changes on sample’s refractive index (n) for a wavelength of 589 nm with a relative precision of 10 −6 [15]. According to Lorentz-Lorenz equation, n can be related to sample density (ρ):n2−1n2+2=r ρ where r is the specific refractivity, accounts for the electronic polarizability of the sample.…”

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%

“…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%

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

Gouveia

Lixandrão

Tavares

et al. 2019

Foods

View full text Add to dashboard Cite

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“…where n(t) is the instantaneous refractive index, A n is the refractive index amplitude, and n is the average response to T, which will hereafter be referred as N MEAN . In accordance with the literature [33,39], the temperature modulation part described in Equations ( 4) and ( 5) yields complementary information about thermal expansion, namely the dynamic thermal volume expansion coefficient β and β (Equations ( 6) and ( 7), respectively) [37].…”

Section: Temperature Modulated Optical Refractometry (Tmor)mentioning

confidence: 52%

“…If the measurement is carried out in a temperature ramp, Equation (3) will yield the volumetric expansion coefficient (β q (T)) [33,36]. When performed isothermally, TMOR analysis might yield the shrinkage (β(t)) [37], which can be a consequence of polymerization and/or molecular rearrangement, as will be discussed later.…”

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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“…There are several methods to study the compatibility of polymers in their alloys. Methods include differential dynamic calorimetry (DSC) [8], thermal-mechanical analysis (DMA) [9], dielectric analysis [10], mechanical properties such as tensile strength [11], optical methods such as refractive index determination [12], thermal expansion measurement [13], morphological studies using TEM [14], SEM [15], etc. The thermal stability of polymers depends on a variety of factors.…”

Section: Introductionmentioning

confidence: 99%

Study on Kinetics of Thermal Degradation of Polymethyl Methacrylate/Cyclic Olefin Copolymer Blend

Khosravinezhad¹,

Kazemi²

2021

Preprint

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In this investigation, polymethyl methacrylate (PMMA) was mixed with cyclic olefin copolymer (COC) because of its hardness, strength, and transparency properties. The results of thermal analysis through TGA and DTG showed that the thermal properties of the alloy are improved using 40% cyclic olefin copolymer. Kinetics of thermal degradation (pyrolysis) of polymers have been studied and analyzed and thermal pyrolysis of polymethyl methacrylate and cyclic olefin copolymer thermoplastic polymer was conducted. The computation of kinetic analysis is measured along with the different methods used to study the kinetics. The activation energy (E) of degradation of studied materials was estimated using Ozawa Flynn and Wall (OFW), Starink and Kissinger’s methods, and evaluation of three kinetic parameters taken appropriate kinetic model in terms of percent change for both types of polymers have been proposed, and finally, simulated curves were compared with the experimental curves. Both mechanisms of degradation for COC and PMMA under nitrogen atmosphere will reflect intramolecular transfer and random scission of the main chain.

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Polymerization-induced shrinkage and dynamic thermal expansion behavior during network formation of polyurethanes

Cited by 15 publications

References 26 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

Study on Kinetics of Thermal Degradation of Polymethyl Methacrylate/Cyclic Olefin Copolymer Blend

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