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

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

Hemijska industrija ◽

10.2298/hemind120814111j ◽

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.

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

Nanomaterials ◽

10.3390/nano11081990 ◽

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.

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

Journal of Composites Science ◽

10.3390/jcs4030111 ◽

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.

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The curing behaviour and thermo-mechanical properties of core–shell rubber-modified epoxy nanocomposites

Polymers and Polymer Composites ◽

10.1177/0967391118820618 ◽

2018 ◽

Vol 27 (3) ◽

pp. 168-175

Author(s):

Dong Quan ◽

Alojz Ivankovic

Keyword(s):

Mechanical Properties ◽

Abrupt Onset ◽

Core Shell ◽

Curing Process ◽

Epoxy Nanocomposites ◽

Scanning Calorimetry ◽

Diffusion Controlled ◽

Reactive Groups ◽

Higher Temperature ◽

Physical Changes

This work investigates the effects of core–shell rubber (CSR) nanoparticles on the curing behaviour and thermo-mechanical properties of an epoxy using differential scanning calorimetry and dynamic mechanical thermal analysis approaches. Interaction between CSR nanoparticles and epoxy matrix is detected at a temperature of approximately 97°C in the curing process. This results in an increase in the glass transition temperature ( Tg) of the cured nanocomposites. Given the semi-dynamic curing schedule, the curing process of all the epoxy nanocomposites consists of an abrupt onset stage followed by a slow diffusion-controlled stage. Higher temperature is required to initiate the curing for the epoxy nanocomposites with higher loading of CSR nanoparticles. This is attributed to the physical changes caused by the addition of CSR nanoparticles, such as the increase in the viscosity and the reduction in the density of the reactive groups. The storage modulus of the epoxy decreases in the glassy region but remains constant in the rubbery region due to the incorporation of CSR nanoparticles.

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In-Out Surface Modification of Halloysite Nanotubes (HNTs) for Excellent Cure of Epoxy: Chemistry and Kinetics Modeling

Nanomaterials ◽

10.3390/nano11113078 ◽

2021 ◽

Vol 11 (11) ◽

pp. 3078

Author(s):

Shahab Moghari ◽

Seyed Hassan Jafari ◽

Mohsen Khodadadi Yazdi ◽

Maryam Jouyandeh ◽

Aleksander Hejna ◽

...

Keyword(s):

Surface Modification ◽

Surface Engineering ◽

Reaction Order ◽

Halloysite Nanotubes ◽

Significant Rise ◽

Autocatalytic Reaction ◽

Scanning Calorimetry ◽

Cure Reaction ◽

Exponential Factor ◽

Dsc Measurements

In-out surface modification of halloysite nanotubes (HNTs) has been successfully performed by taking advantage of 8-hydroxyquinolines in the lumen of HNTs and precisely synthesized aniline oligomers (AO) of different lengths (tri- and pentamer) anchored on the external surface of the HNTs. Several analyses, including FTIR, H-NMR, TGA, UV-visible spectroscopy, and SEM, were used to establish the nature of the HNTs’ surface engineering. Nanoparticles were incorporated into epoxy resin at 0.1 wt.% loading for investigation of the contribution of surface chemistry to epoxy cure behavior and kinetics. Nonisothermal differential scanning calorimetry (DSC) data were fed into home-written MATLAB codes, and isoconversional approaches were used to determine the apparent activation energy (Eα) as a function of the extent of cure reaction (α). Compared to pristine HNTs, AO-HNTs facilitated the densification of an epoxy network. Pentamer AO-HNTs with longer arms promoted an Excellent cure; with an Eα value that was 14% lower in the presence of this additive than for neat epoxy, demonstrating an enhanced cross-linking. The model also predicted a triplet of cure (m, n, and ln A) for autocatalytic reaction order, non-catalytic reaction order, and pre-exponential factor, respectively, by the Arrhenius equation. The enhanced autocatalytic reaction in AO-HNTs/epoxy was reflected in a significant rise in the value of m, from 0.11 to 0.28. Kinetic models reliably predict the cure footprint suggested by DSC measurements.

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Isoconversional kinetic analysis of the alkyd/melamine resins curing

Chemical Industry and Chemical Engineering Quarterly ◽

10.2298/ciceq111110059j ◽

2013 ◽

Vol 19 (2) ◽

pp. 253-262 ◽

Cited By ~ 4

Author(s):

Mirjana Jovicic ◽

Radmila Radicevic ◽

Jelena Pavlicevic ◽

Oskar Bera

Keyword(s):

Catalytic Effect ◽

Curing Kinetics ◽

Isoconversional Methods ◽

Hydroxyl Group ◽

Kinetics Analysis ◽

Heating Rates ◽

Scanning Calorimetry ◽

Alkyd Resins ◽

Isoconversional Kinetic Analysis ◽

Wall Method

The curing reaction for the mixtures of alkyd resins based on ricinoleic acid, phthalic anhydride and three polyols (glycerin, trimethylolpropane or ethoxylated pentaerythritol) with two different commercial melamine resins was investigated by differential scanning calorimetry (DSC). The curing kinetics analysis was performed using the isoconversional methods (Ozawa-Flynn-Wall, Kissinger-Akahira-Sunose and Friedman). Isoconversional methods were carried out with three heating rates (5, 10 and 20?C/min) in a scanning temperature range from 40 to 250?C. It was found that the curing activation energy of resin mixtures is influenced by alkyd and melamine resin type due to the catalytic effect of hydroxyl group on the reactions. The dependence of apparent curing degree on time, which was obtained by mathematical transformations of dynamic DSC data using Ozawa-Flynn-Wall method, describes well the isothermal DSC experiments.

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Study of the crystallization kinetics of a Zr57Cu15.4Ni12.6Al10Nb5 amorphous alloy

International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde) ◽

10.1515/ijmr-2020-1111009 ◽

2020 ◽

Vol 111 (10) ◽

pp. 849-856

Author(s):

Hui E. Hu ◽

Zhou Lu ◽

Xiao Hong Su ◽

Jing Xin Deng

Keyword(s):

Amorphous Alloy ◽

Crystallization Kinetics ◽

Nucleation Rate ◽

Isothermal Crystallization ◽

Growth Process ◽

Exothermic Peak ◽

Heating Rates ◽

Scanning Calorimetry ◽

Isothermal Crystallization Kinetics ◽

Diffusion Controlled

Abstract The non-isothermal crystallization kinetics with heating rates ranging from 10 K s-1to 80 K s-1and the isothermal crystallization kinetics during annealing from the glass transition temperature to the crystallization onset temperature of a Zr57Cu15.4Ni12.6Al10Nb5 amorphous alloy were studied in detail using X-ray diffraction and differential scanning calorimetry. During non-isothermal crystallization, it is more difficult to nucleate than to grow, and the crystallization resistance increases first and then decreases. During isothermal crystallization of the alloy from 713- 728 K, there are two exothermic peaks corresponding to a diffusion-controlled growth process with decreasing nucleation rate and increasing nucleation rate. From 733- 748 K, only one exothermic peak appears, and the growth process is controlled by the interface with decreasing nucleation rate. Isothermal crystallization is a process in which the crystallization resistance increases. The resistance of isothermal crystallization is less than that of non-isothermal crystallization.

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A new resin with improved processability and thermal stability

High Performance Polymers ◽

10.1177/0954008315626806 ◽

2016 ◽

Vol 29 (1) ◽

pp. 13-25 ◽

Cited By ~ 3

Author(s):

Liping Sheng ◽

Jingcheng Zeng ◽

Suli Xing ◽

Changping Yin ◽

Jinshui Yang ◽

...

Keyword(s):

Thermal Stability ◽

Synergistic Effect ◽

Curing Temperature ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

Curing Time ◽

Heating Rates ◽

Scanning Calorimetry ◽

Cure Reaction ◽

Excellent Thermal Stability

To maintain outstanding thermal stability, amino- and hydroxyl-containing phthalonitrile monomers, 4-(4-aminophenoxy)-phthalonitrile (APN) and 4-(4-hydroxyphenoxy)-phthalonitrile (HPN) were selected and synthesized. Their structures were confirmed by proton nuclear magnetic resonance spectroscopy. Their curing polymers were characterized by Fourier transform infrared spectroscopy. The self-catalytic curing behaviors of the monomers were investigated by differential scanning calorimetry (DSC) at different heating rates. From the results, APN exhibits a higher curing temperature, while HPN exhibits a longer curing time. Then, mixtures of these monomers were investigated by DSC. The result shows that the 50/50 mixture exhibits different autocatalytic behaviors: the curing temperature is lower than that of APN and the curing time of the mixture is shorter than that of HPN. Furthermore, thermogravimetric analysis shows that the polymer from the mixture exhibits higher temperature of 5% weight loss ( T5%) and char yield value at 800°C than those of the polymers from each monomer. All these results indicate that the new mixture resin exhibits improved processability with excellent thermal stability, attributed to the synergistic effect between similar monomers; the synergistic effect optimizes the cure reaction kinetics and promotes cross-linking reactions, thereby producing an excellent resin; this approach is a new method for improving the processability without sacrificing thermal stability.

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Curing kinetics of two commercial urea-formaldehyde adhesives studied by isoconversional method

Hemijska industrija ◽

10.2298/hemind110912088p ◽

2011 ◽

Vol 65 (6) ◽

pp. 717-726 ◽

Cited By ~ 6

Author(s):

Mladjan Popovic ◽

Jaroslava Budinski-Simendic ◽

Mirjana Jovicic ◽

Joszef Mursics ◽

Milanka Djiporovic-Momcilovic ◽

...

Keyword(s):

Activation Energy ◽

Urea Formaldehyde ◽

Curing Kinetics ◽

Isoconversional Methods ◽

Isoconversional Method ◽

Reaction Enthalpy ◽

Heating Rates ◽

Scanning Calorimetry ◽

Dsc Measurements ◽

Kinetics Of

Differential scanning calorimetry (DSC) was used to evaluate the curing kinetics of two commercial urea-formaldehyde (UF) adhesives having different formaldehyde to urea (F/U) ratio of 1.112 (UF1) and 1.086 (UF2). DSC measurements were done in dynamic scanning regime with heating rates of 5, 10, 15 and 20?C?min-1 in order to determine the activation energy for each adhesive. Obtained data were analyzed using isoconversional methods with application of Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose kinetic models. In addition, different catalyst levels were tested at the heating rate of 10?C/min. Results showed that the adhesive with higher F/U ratio achieved higher activation energy, while having lower peak temperature of curing reaction. It was also noticed that the increase of catalyst level influenced the increase of reaction enthalpy of the adhesive with lower F/U ratio.

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