Protocol for nonisothermal cure analysis of thermoset composites

Jouyandeh, Maryam; Paran, Seyed Mohammad Reza; Jannesari, Ali; Puglia, Debora; Saeb, Mohammad Reza

doi:10.1016/j.porgcoat.2019.02.040

Cited by 95 publications

(43 citation statements)

References 32 publications

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“…Likewise, dimensionless cure window is defined as ΔT* = ΔT Comp /ΔT Ref . ), where ΔT = T endset – T onset and the numerator and the denominator are the ΔT of the composite and that of neat resin, respectively [ 44 , 45 ]. Such quantities together with the exothermal peak temperature ( T p ) and the total heat released during crosslinking reaction ( ΔH ) as a function of heating rate applied in DSC test are included in Table 1 .…”

Section: Resultsmentioning

confidence: 99%

Bulk-Surface Modification of Nanoparticles for Developing Highly-Crosslinked Polymer Nanocomposites

et al. 2020

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Surface modification of nanoparticles with functional molecules has become a routine method to compensate for diffusion-controlled crosslinking of thermoset polymer composites at late stages of crosslinking, while bulk modification has not carefully been discussed. In this work, a highly-crosslinked model polymer nanocomposite based on epoxy and surface-bulk functionalized magnetic nanoparticles (MNPs) was developed. MNPs were synthesized electrochemically, and then polyethylene glycol (PEG) surface-functionalized (PEG-MNPs) and PEG-functionalized cobalt-doped (Co-PEG-MNPs) particles were developed and used in nanocomposite preparation. Various analyses including field-emission scanning electron microscopy, Fourier-transform infrared spectrophotometry (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) were employed in characterization of surface and bulk of PEG-MNPs and Co-PEG-MNPs. Epoxy nanocomposites including the aforementioned MNPs were prepared and analyzed by nonisothermal differential scanning calorimetry (DSC) to study their curing potential in epoxy/amine system. Analyses based on Cure Index revealed that incorporation of 0.1 wt.% of Co-PEG-MNPs into epoxy led to Excellent cure at all heating rates, which uncovered the assistance of bulk modification of nanoparticles to the crosslinking of model epoxy nanocomposites. Isoconversional methods revealed higher activation energy for the completely crosslinked epoxy/Co-PEG-MNPs nanocomposite compared to the neat epoxy. The kinetic model based on isoconversional methods was verified by the experimental rate of cure reaction.

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Section: Resultsmentioning

confidence: 99%

Bulk-Surface Modification of Nanoparticles for Developing Highly-Crosslinked Polymer Nanocomposites

et al. 2020

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“…On the other hand, by increasing the heating rate, this effect is diminished as a result of the higher kinetic energy per molecule, which increases the mobility and, consequently, the number of collisions among curing moieties. Based on these evaluations, one of the best ways to determine kinetic parameters such as activation energy (Ea) and order of reaction is to apply independent isoconversional methods that do not require model-fitting for calculation of Ea and Frequency factor (A) [23]. At a given α, these methods assume that the reaction rate is determined purely in terms of temperature (T).…”

Section: Quantitative Cure Analysismentioning

confidence: 99%

“…Figure 6 demonstrates correlation of Ea and α as calculated by the Friedman and Kissinger approaches for epoxy and AHP/epoxy nanocomposites. The increasing evolution of activation energy with respect to cure conversion in the range of 0.1 to 0.9 is indicative of the transition from a rapid chemical-control to a gentle diffusion-control phase of the reaction, leading to an increase in the activation energy required for epoxy ring opening at high viscosity, and the difficult accessibility of Based on these evaluations, one of the best ways to determine kinetic parameters such as activation energy (E a ) and order of reaction is to apply independent isoconversional methods that do not require model-fitting for calculation of E a and Frequency factor (A) [23]. At a given α, these methods assume that the reaction rate is determined purely in terms of temperature (T).…”

Section: Quantitative Cure Analysismentioning

confidence: 99%

“…Low concentration epoxy nanocomposites of AHP (0.1, 0.3 and 0.5 wt.% based on epoxy weight) were prepared from a solution of AHP in ethanol to avoid solubilization. Differential scanning calorimetry (DSC) at various heating rates of 5, 10, 15 and 20 • C/min was performed to evaluate cure behavior and kinetics in terms of enthalpy of cure, curing temperature window, featured in Cure Index and based on a general protocol [10,23]. The samples were designated with cure labels including Poor, Good and Excellent.…”

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Curing Kinetics and Thermal Stability of Epoxy Composites Containing Newly Obtained Nano-Scale Aluminum Hypophosphite (AlPO2)

et al. 2020

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For the first time, nano-scale aluminum hypophosphite (AlPO2) was simply obtained in a two-step milling process and applied in preparation of epoxy nanocomposites varying concentration (0.1, 0.3, and 0.5 wt.% based on resin weight). Studying the cure kinetics and thermal stability of these nanocomposites would pave the way toward the design of high-performance nanocomposites for special applications. Scanning electron microscopy (SEM) and transmittance electron microscopy (TEM) revealed AlPO2 particles having domains less than 60 nm with high potential for agglomeration. Excellent (at heating rate of 5 °C/min) and Good (at heating rates of 10, 15 and 20 °C/min) cure states were detected for nanocomposites under nonisothermal differential scanning calorimetry (DSC). While the dimensionless curing temperature interval (ΔT*) was almost equal for epoxy/AlPO2 nanocomposites, dimensionless heat release (ΔH*) changed by densification of polymeric network. Quantitative cure analysis based on isoconversional Friedman and Kissinger methods gave rise to the kinetic parameters such as activation energy and the order of reaction as well as frequency factor. Variation of glass transition temperature (Tg) was monitored to explain the molecular interaction in the system, where Tg increased from 73.2 °C for neat epoxy to just 79.5 °C for the system containing 0.1 wt.% AlPO2. Moreover, thermogravimetric analysis (TGA) showed that nanocomposites were thermally stable.

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“…The cure kinetics of silicone nanocomposite was investigated in accordance with the nonisothermal cure analysis proposed in a comprehensive methodology. [ 38 ]…”

Section: Cure Analysismentioning

confidence: 99%

Cure Kinetics of Silicone/Halloysite Nanotube Composites

Karami

Jazani

Navarchian

et al. 2020

Vinyl Additive Technology

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Properties of silicone thin films and coatings are strongly hooked on curing reaction. We discussed about cure process of silicone nanocomposites containing halloysite nanotube (HNT) at different loading levels (0.5, 1.0, and 2.0 phr), both qualitatively and quantitatively. Systems containing pristine and aminosilane‐functionalized HNT were cured nonisothermally and heat buildup of the reaction was recorded by differential scanning calorimetry (DSC) in terms of the time and the temperature varying the heating rate. Integral and differential isoconversional methods suggested that apparent activation energy (Ea) was strongly affected by the loading level and surface treatment of HNT. The exponent of the autocatalytic reaction (m) was decreased by the introduction and increasing the amount of pristine, and more remarkably the functionalized HNT to the silicone, where the Friedman method suggested 0.249, 0.119, and 0.045 values of m for the neat silicone rubber, and the nanocomposites containing 1 phr of pristine and functionalized HNT, respectively. The logarithm of frequency factor, ln A was also increased due to the enhanced collisions between curing moieties in the presence of pristine and functionalized HNTs form 23.57 seconds for silicone rubber to 24.25 seconds and 25.19 seconds for silicone nanocomposite containing 2 phr of pristine and functionalized HNT, respectively. The theoretical rate of reaction was in agreement with experimental data.

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Protocol for nonisothermal cure analysis of thermoset composites

Cited by 95 publications

References 32 publications

Bulk-Surface Modification of Nanoparticles for Developing Highly-Crosslinked Polymer Nanocomposites

Bulk-Surface Modification of Nanoparticles for Developing Highly-Crosslinked Polymer Nanocomposites

Curing Kinetics and Thermal Stability of Epoxy Composites Containing Newly Obtained Nano-Scale Aluminum Hypophosphite (AlPO2)

Cure Kinetics of Silicone/Halloysite Nanotube Composites

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