scholarly journals A Comparative Study on Cure Kinetics of Layered Double Hydroxide (LDH)/Epoxy Nanocomposites

2020 ◽  
Vol 4 (3) ◽  
pp. 111
Author(s):  
Zohre Karami ◽  
Seyed Mohammad Reza Paran ◽  
Poornima Vijayan P. ◽  
Mohammad Reza Ganjali ◽  
Maryam Jouyandeh ◽  
...  
Keyword(s):  
Layered Double Hydroxide ◽  
Cure Kinetics ◽  
Frequency Factor ◽  
Isoconversional Methods ◽  
Epoxide Ring ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry ◽  
Noncatalytic Reaction ◽  
Double Hydroxide ◽  
Kinetics Of

Layered double hydroxide (LDH) minerals are promising candidates for developing polymer nanocomposites and the exchange of intercalating anions and metal ions in the LDH structure considerably affects their ultimate properties. Despite the fact that the synthesis of various kinds of LDHs has been the subject of numerous studies, the cure kinetics of LDH-based thermoset polymer composites has rarely been investigated. Herein, binary and ternary structures, including [Mg0.75 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, [Mg0.75 Al0.25 (OH)2]0.25+ [(NO3−)0.25∙m H2O]0.25− and [Mg0.64 Zn0.11 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, have been incorporated into epoxy to study the cure kinetics of the resulting nanocomposites by differential scanning calorimetry (DSC). Both integral and differential isoconversional methods serve to study the non-isothermal curing reactions of epoxy nanocomposites. The effects of carbonate and nitrate ions as intercalating agents on the cure kinetics are also discussed. The activation energy of cure (Eα) was calculated based on the Friedman and Kissinger–Akahira–Sunose (KAS) methods for epoxy/LDH nanocomposites. The order of autocatalytic reaction (m) for the epoxy/Mg-Al-NO3 (0.30 and 0.254 calculated by the Friedman and KAS methods, respectively) was smaller than that of the neat epoxy, which suggested a shift of the curing mechanism from an autocatalytic to noncatalytic reaction. Moreover, a higher frequency factor for the aforementioned nanocomposite suggests that the incorporation of Mg-Al-NO3 in the epoxy composite improved the curability of the epoxy. The results elucidate that the intercalating anions and the metal constituent of LDH significantly govern the cure kinetics of epoxy by the participation of nitrate anions in the epoxide ring-opening reaction.

scholarly journals Epoxy/Ionic Liquid-Modified Mica Nanocomposites: Network Formation–Network Degradation Correlation

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1990
Author(s):  
Maryam Jouyandeh ◽  
Vahideh Akbari ◽  
Seyed Mohammad Reza Paran ◽  
Sébastien Livi ◽  
Luanda Lins ◽  
...  
Keyword(s):  
Activation Energy ◽  
Network Formation ◽  
Isoconversional Methods ◽  
Epoxide Ring ◽  
Segmental Motion ◽  
Heating Rates ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry ◽  
Amine Curing ◽  
Kinetics Of

We synthesized pristine mica (Mica) and N-octadecyl-N’-octadecyl imidazolium iodide (IM) modified mica (Mica-IM), characterized it, and applied it at 0.1–5.0 wt.% loading to prepare epoxy nanocomposites. Dynamic differential scanning calorimetry (DSC) was carried out for the analysis of the cure potential and kinetics of epoxy/Mica and epoxy/Mica-IM curing reaction with amine curing agents at low loading of 0.1 wt.% to avoid particle aggregation. The dimensionless Cure Index (CI) was used for qualitative analysis of epoxy crosslinking in the presence of Mica and Mica-IM, while qualitative cure behavior and kinetics were studied by using isoconversional methods. The results indicated that both Mica and Mica-IM improved the curability of epoxy system from a Poor to Good state when varying the heating rate in the interval of 5–15 °C min−1. The isoconversional methods suggested a lower activation energy for epoxy nanocomposites with respect to the blank epoxy; thus, Mica and Mica-IM improved crosslinking of epoxy. The higher order of autocatalytic reaction for epoxy/Mica-IM was indicative of the role of liquid crystals in the epoxide ring opening. The glass transition temperature for nanocomposites containing Mica and Mica-IM was also lower than the neat epoxy. This means that nanoparticles participated the reaction because of being reactive, which decelerated segmental motion of the epoxy chains. The kinetics of the thermal decomposition were evaluated for the neat and mica incorporated epoxy nanocomposites epoxy with varying Mica and Mica-IM amounts in the system (0.5, 2.0 and 5.0 wt.%) and heating rates. The epoxy/Mica-IM at 2.0 wt.% of nanoparticle showed the highest thermal stability, featured by the maximum value of activation energy devoted to the assigned system. The kinetics of the network formation and network degradation were correlated to demonstrate how molecular-level transformations can be viewed semi-experimentally.

Kinetics of the Curing Reaction of a Diglycidyl Ether of Bisphenol with a Methanol Etherified Amino Resin

2011 ◽  
Vol 380 ◽  
pp. 60-63 ◽  
Author(s):  
Yong Lv ◽  
Zhu Long ◽  
Shi Yong Luo ◽  
Lei Dai
Keyword(s):  
Cure Kinetics ◽  
Frequency Factor ◽  
Diglycidyl Ether ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Curing Reaction ◽  
Before And After ◽  
Amino Resin ◽  
Chemical Products ◽  
Kinetics Of

Subscript text Subscript textEpoxy resins have been widely used for inner coating in food can and other chemical products storage containers. Differential scanning calorimetry (DSC) was used at different heating rates to study the cure kinetics of the diglycidyl ether of bisphenol A (DGEBA) with a methanol etherified amino resin (MEAR). The apparent activation energy derived from Kissinger and Ozawa methods is 35.67KJ/mol and 40.27kJ/mol, respectively. The reaction order evaluated by Crane equation is 0. 95 and the frequency factor is 1.12×104s-1. Reaction mechanism was monitored by FTIR spectra of the reaction mixtures before and after curing. The curing reaction below 200°C is between alkoxylmethyl (>NCH2OCH3) and epoxide group, not between alkoxylmethyl and hydroxyls.

scholarly journals Nonisothermal Cure Kinetics of Epoxy/Polyvinylpyrrolidone Functionalized Superparamagnetic Nano-Fe3O4 Composites: Effect of Zn and Mn Doping

2020 ◽  
Vol 4 (2) ◽  
pp. 55 ◽  
Author(s):  
Maryam Jouyandeh ◽  
Mohammad Reza Ganjali ◽  
Farzad Seidi ◽  
Huining Xiao ◽  
Mohammad Reza Saeb
Keyword(s):  
Superparamagnetic Iron Oxide ◽  
Cure Kinetics ◽  
Isoconversional Methods ◽  
Reaction Model ◽  
Partial Replacement ◽  
Scanning Calorimetry ◽  
Nano Fe3o4 ◽  
Kinetics Of ◽  
Mn Doped ◽  
Good Agreement

The effects of the bulk and surface modification of nanoparticles on the cure kinetics of low-filled epoxy nanocomposites containing electrochemically synthesized polyvinylpyrrolidone (PVP) functionalized superparamagnetic iron oxide (PVP-SPIO), Zn-doped PVP-SPIO (Zn-PVP-SPIO), and Mn-doped PVP-SPIO (Mn-PVP-SPIO) were studied using differential scanning calorimetry (DSC) and cure kinetics analyses. Integral and differential isoconversional methods were used to calculate the activation energies (Eα) and consequently propose the appropriate reaction model for the curing reaction under nonisothermal conditions. According to the alteration of Eα versus the fractional extent of conversion, the Eα trend was changed through the partial replacement of Fe2+ sites by the Zn2+ and Mn2+ cations in the general formula of MxFe3-xO4, due to smaller amounts of energy being required for curing by the incorporation of Zn-PVP-SPIO and Mn-PVP-SPIO nanoparticles into the epoxy resin. A good agreement was observed between the theoretical calculation and the observed calorimetric data for the model validation.

scholarly journals The influence of montmorillonite content on the kinetics of curing of epoxy nanocomposites

2012 ◽  
Vol 66 (6) ◽  
pp. 863-870
Author(s):  
Mirjana Jovicic ◽  
Oskar Bera ◽  
Jelena Pavlicevic ◽  
Vesna Simendic ◽  
Radmila Radicevic
Keyword(s):  
Isoconversional Methods ◽  
Curing Process ◽  
Heating Rates ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry ◽  
Epoxy Amine ◽  
Friedman Method ◽  
Kinetics Of ◽  
Dsc Curves ◽  
Energy Activation

In this work, the attention was paid at the investigation of montmorillonite dispersion in epoxy/amine systems due to improved final properties of the nanocomposites. The influence of different montmorillonite content on the kinetics of curing of epoxy/Jeffamine D-230 systems was followed by differential scanning calorimetry (DSC). The curing of epoxy nanocomposites was performed using dynamic regime at three different heating rates: 5, 10 and 20?C/min. Three isoconversional methods were applied: two integral (Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose methods) and one differential (Friedman method). The presence of montmorillonite (MMT) causes the beginning of curing at lower temperatures. The shape of the DSC curves has been changed by the addition of MMT, supporting the hypothesis of a change in the reaction mechanism. For hybrids with 3 and 5 wt.% of MMT, the E? dependence is very similar to those found for the reference system (epoxy/Jeffamine D-230) for the curing degree less than 60%. The hybrid with 10 wt.% of MMT has lower energy activation in regard to the referent system without montmorillonite. Greater differences are observed in the second part of the reaction, where it is known that the curing process is more controlled by diffusion (?>0.60). The Ea value increases at the end of the reaction (??1), which was observed for all systems, and is more pronounced in the presence of montmorillonite.

Effects of additives on the cure kinetics of vinyl ester pultrusion resins

2021 ◽  
pp. 002199832110015
Author(s):  
Alexander Vedernikov ◽  
Yaroslav Nasonov ◽  
Roman Korotkov ◽  
Sergey Gusev ◽  
Iskander Akhatov ◽  
...  
Keyword(s):  
Vinyl Ester ◽  
Mean Squared Error ◽  
Cure Kinetics ◽  
Zinc Stearate ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
Predicted Values ◽  
Kinetics Of ◽  
Final Degree

Pultrusion is a highly efficient composite manufacturing process. To accurately describe pultrusion, an appropriate model of resin cure kinetics is required. In this study, we investigated cure kinetics modeling of a vinyl ester pultrusion resin (Atlac 430) in the presence of aluminum hydroxide (Al(OH)3) and zinc stearate (Zn(C18H35O2)2) as processing additives. Herein, four different resin compositions were studied: neat resin composition, composition with Al(OH)3, composition comprising Zn(C18H35O2)2, and composition containing both Al(OH)3 and Zn(C18H35O2)2. To analyze each composition, we performed differential scanning calorimetry at the heating rates of 5, 7.5, and 10 K/min. To characterize the cure kinetics of Atlac 430, 16 kinetic models were tested, and their performances were compared. The model based on the [Formula: see text]th-order autocatalytic reaction demonstrated the best results, with a 4.5% mean squared error (MSE) between the experimental and predicted data. This study proposes a method to reduce the MSE resulting from the simultaneous melting of Zn(C18H35O2)2. We were able to reduce the MSE by approximately 34%. Numerical simulations conducted at different temperatures and pulling speeds demonstrated a significant influence of resin composition on the pultrusion of a flat laminate profile. Simulation results obtained for the 600 mm long die block at different die temperatures (115, 120, 125, and 130 °C) showed that for a resin with a final degree of cure exceeding 95% at the die exit, the maximum difference between the predicted values of pulling speed for a specified set of compositions may exceed 1.7 times.

Investigating the relationship between tack and degree of conversion in DGEBA-based epoxy resin cured with dicyandiamide and diuron

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ali Kuliaei ◽  
Iraj Amiri Amraei ◽  
Seyed Rasoul Mousavi
Keyword(s):  
Epoxy Resin ◽  
Reaction Order ◽  
Theoretical Data ◽  
Cure Kinetics ◽  
Diglycidyl Ether ◽  
Degree Of Conversion ◽  
Ozawa Method ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Kinetics Of

Abstract The purpose behind this research was to determine the optimum formulation and investigate the cure kinetics of a diglycidyl ether of bisphenol-A (DGEBA)-based epoxy resin cured by dicyandiamide and diuron for use in prepregs. First, all formulations were examined by the tensile test, and then, the specimens with higher mechanical properties were further investigated by viscometry and tack tests. The cure kinetics of the best formulation (based on tack test) in nonisothermal mode was investigated using differential scanning calorimetry at different heating rates. Kissinger and Ozawa method was used for determining the kinetic parameters of the curing process. The activation energy obtained by this method was 71.43 kJ/mol. The heating rate had no significant effect on the reaction order and the total reaction order was approximately constant ( m + n ≅ 2.1 $m+n\cong 2.1$ ). By comparing the experimental data and the theoretical data obtained by Kissinger and Ozawa method, a good agreement was seen between them. By increasing the degree of conversion, the viscosity decreased; as the degree of conversion increased, so did the slope of viscosity. The results of the tack test also indicated that the highest tack could be obtained with 25% progress of curing.

Sign in / Sign up

Export Citation Format

Share Document