Reaction kinetics,thermal properties of tetramethyl biphenyl epoxy resin cured with aromatic diamine

Epoxy resins, 4, 4′‐diglycidyl (3, 3′, 5, 5′‐tetramethylbiphenyl) epoxy resin (TMBP) containing rigid rod structure as a class of high performance polymers has been researched. The investigation of cure kinetics of TMBP and diglycidyl ether of bisphenol‐A epoxy resin (DGEBA) cured with p‐phenylenediamine (PDA) was performed by differential scanning calorimeter using an isoconversional method with dynamic conditions. The effect of the molar ratios of TMBP to PDA on the cure reaction kinetics was studied. The results showed that the curing of epoxy resins contains different stages. The activation energy was dependent of the degree of conversion. At the early of curing stages, the activation energy showed the activation energy took as maximum value. The effects of rigid rod groups and molar ratios of TMBP to PDA for the thermal properties were investigated by the DSC, DMA and TGA. The cured 2/1 TMBP/PDA system with rigid rod groups and high crosslink density had shown highest T_g and thermal degradation temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Relationship between viscoelastic properties and gelation in the epoxy/phenol‐novolac blend system with N‐benzylpyrazinium salt as a latent thermal catalyst

A study of viscoelastic properties and gelation in epoxy/phenol‐novolac blend system initiated with 1 wt % of N‐benzylpyrazinium hexafluoroantimonate (BPH) as a latent cationic thermal initiator was performed by analysis of rheological properties using a rheometer. Latent behavior was investigated by measuring the conversion as a function of curing temperature using traditional curing agents, such as ethylene diamine (EDA) and nadic methyl anhydride (NMA) in comparison to BPH. In the relationship between viscoelastic properties and gelation of epoxy/phenol‐novolac blend system, the time of modulus crossover was dependent on high frequency and cure temperature. The activation energy (E_c) for crosslinking from rheometric analysis increased within the composition range of 20–40 wt % phenol‐novolac resin. The 40 wt % phenol‐novolac (N40) to epoxy resin showed the highest value in the blend system, due to the three‐dimensional crosslinking that can take place between hydroxyl groups within the phenol resin or epoxides within the epoxy resin involving polyaddition of the initiator with BPH. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2299–2308, 2001     

Development of a DOPO‐containing melamine epoxy hardeners and its thermal and flame‐retardant properties of cured products

In this study, a novel Schiff base of melamine used as flame‐retardant curing agent for epoxy resins, was synthesized via condensation reaction of 4‐hydroxybenzaldehyde with melamine, followed by the addition of 9,10‐dihydro‐9‐oxa‐10‐phosphaphen‐anthrene 10‐oxide (DOPO) to the resulting imine linkage. The structure of DOPO‐containing melamine Schiff base (P‐MSB) was characterized by Fourier transformed infrared spectroscopy, ¹H‐nuclear magnetic resonance (¹H‐NMR) and ³¹P‐NMR. The compound (P‐MSB) was used as a reactive flame retardant in o‐cresol formaldehyde novolac epoxy resin (CNE) to prepare flame‐retardant epoxy resins for electronic application. The thermal and flame‐retardant properties of the epoxy resins cured by various equivalent ratios phenol formaldehyde novolac (PN) and P‐MSB were investigated by the nonisothermal differential scanning calorimetry, the thermogravimetric analysis, and limiting oxygen index test. The obtained results showed that the cured epoxy resins possessed high T_g (165°C) and good thermal stability (T_5%, 321°C). Moreover, the P‐MSB/CNE systems exhibited higher limiting oxygen index (35) and more char was maintained in P‐MSB/CNE systems than that in PN/CNE system and the effective synergism of phosphorus–nitrogen indicated their excellent flame retardancy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Cure kinetics of epoxy/MWCNTs nanocomposites: Nonisothermal calorimetric and rheokinetic techniques

Nonisothermal calorimetric and isothermal rheokinetic analyses were used to study cure kinetics of epoxy/anhydride systems containing very low concentration of pristine and amine‐functionalized multiwalled carbon nanotubes (MWCNTs). Isoconversional methods were applied in calorimetric modeling of cure kinetics. E _α vs. α dependency and autocatalytic nature of curing were identified for both types of nanocomposites by isoconversional models. Fall in E _α value from 90 to 82.5 kJ mol^?1 thanks to amine functionalization (with E _α of blank epoxy/anhydride of 80.3 kJ mol^?1) was indicative of high potential of nanocomposites to cure at low concentration of functionalized MWCNTs (0.1 g with respect to 100 g of resin). Times of gelation and vitrification of epoxy were measured using storage and loss modulus data provided by isothermal rheokinetic analysis, showing a drop upon attachment of amine groups to MWCNTs. In complete agreement with nonisothermal calorimetric studies, variation of storage and loss modulus of nanocomposites confirmed hindered/accelerated cure devoted to pristine/amine‐functionalized MWCNTs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45221.     

Synthesis of bio-based reactive N/P flame retardant and its curing and flame retarding behavior in epoxy resins

In this study, a pioneering bio-based nitrogen–phosphorus flame retardant and curing accelerator named oxime-phosphazene hexakis [(4-(hydroxyimino) 2-methoxy) phenoxy] cyclotriphosphazene (HAPV) was successfully synthesized using hexachlorocyclotriphosphazene and vanillin. When 5 wt % HAPV was added into epoxy, the limiting oxygen index increased from 22% to 27% and passed UL-94 V-0 (UL is defined as Underwriters Laboratories) rating. Meanwhile, with the addition 5 wt% HAPV, the apparent activation energy (E_a) of HAPV/EP decreased from 20.22 to 67.15 kJ/mol, and the pHRR value was suppressed from 581.21 to 330.18 kW/m². It was due to that the HAPV quenched the combustion chain reaction through the gas phase and condensed phase, forming a dense char layer for blocking the heat transfer. Overall, the study provides an environmentally friendly epoxy flame retardant curing accelerator that shows great potential in epoxy flame retardant applications.     

Improving thermal and flame‐retardant properties of epoxy resins by a novel reactive phosphorous‐containing curing agent

In an attempt to improve thermal and flame‐retardant properties of epoxy resins efficiently, a new reactive phosphorus‐containing curing agent called 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐yl‐(phenylimino)‐(4‐hydroxyphenyl)me‐thane (DOPO‐PHM) was synthesized and was combined with 4,4′‐diaminodiphenyl methane (DDM) to co‐cure epoxy resins (E51), which covalently incorporated halogen‐free DOPO organ groups into the epoxy networks. The chemical structure of this curing agent was confirmed by FTIR, 1D, and 2D NMR spectra. A reaction mechanism during the preparation was proposed, and the electron effect on the stabilization of the carbocation was discussed. Various DDM/DOPO‐PHM molar ratios were used to get the materials with different phosphorus contents. Their dynamic mechanical, thermal, and flame‐retardant properties were evaluated by dynamic mechanical thermal analysis, thermogravimetric analysis, and limiting oxygen index (LOI) respectively. All samples had a single T_g, showing that these epoxy resins were homogeneous phase for long‐term use in spite of adding DOPO‐PHM. Both char yields (under nitrogen and air atmospheres) increased with the increasing of phosphorus content and the LOI values increased from 24.5 for standard resin to 33.5 for phosphorus‐containing resins, indicating the significant enhancement of thermal stability and flame retardancy. POLYM. ENG. SCI., 54:1192–1200, 2014. © 2013 Society of Plastics Engineers     

Advanced isoconversional cure kinetic analysis of epoxy/poly(furfuryl alcohol) bio‐resin system

Furfuryl alcohol as a biomass‐derived monomer was used for synthesizing poly(furfuryl alcohol). A diglycidyl ether of bisphenol A (DGEBA) epoxy resin along with 3% and 15% by weight of the poly(furfuryl alcohol) was cured using an aliphatic amine hardener. The cure kinetics of the DGEBA/poly(furfuryl alcohol)/amine systems were investigated by nonisothermal differential scanning calorimetry. The kinetic triplets [E_α, A_α, and f(α)] were computed by using an integral isoconversional method. Based on the E_α‐dependency results a single‐step autocatalytic model was suggested for the reactions mechanism, however, the A_α‐dependency and f(α) analysis did not confirm the suggested model. Detailed kinetics analysis revealed that the cure reaction mechanism of the DGEBA did not change due to the presence of the poly(furfuryl alcohol) in the degree of conversion range < 0.75, nevertheless, it dramatically changed in the degree of conversion range > 0.75 due to the presence of 15 wt % poly(furfuryl alcohol). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45432.     

Effect of backbone moiety in epoxies on thermal conductivity of epoxy/alumina composite

We chose two commercial epoxies, bisphenol A diglycidyl ether (DGEBA) and 3,3′,5,5′‐tetramethyl‐4,4′‐biphenol diglycidyl ether (TMBP), and synthesized one liquid crystalline epoxy (LCE), 4′4′‐bis(4‐hydroxybenzylidene)‐diaminophenylene diglycidyl ether (LCE‐DP) to investigate the effect of backbone moiety in epoxies on the thermal conductivity of epoxy/alumina composite. The DGEBA structure shows an amorphous state and the TMBP structure displays a crystal phase, whereas the LCE‐DP structure exhibits a liquid crystalline phase. The curing behaviors of them were examined employing 4,4′‐diaminodiphenylsulfone (DDS) as a curing agent. The heat of curing of epoxy resin was measured with dynamic differential scanning calorimetry (DSC). Alumina (Al₂O₃) of commercial source was applied as an inorganic filler. Thermal conductivity was measured by laser flash method and compared with value predicted by two theoretical models, Lewis‐Nielsen and Agari‐Uno. The results indicated that the thermal conductivity of the LCE‐DP structure was larger than that of the commercial epoxy resins such as TMBP and DGEBA and the experimental data fitted quite well in the values estimated by Agari‐Uno model. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Cure kinetics and catalyzed effect of hydroxyl group of LC diglycidyl ether of bisphenol‐S with aromatic diamines

The curing reactions of liquid crystalline 4,4′‐bis‐(2,3‐epoxypropyloxy)‐sulfonyl‐bis(1,4‐phenylene) (p‐BEPSBP) with 4,4′‐diaminodiphenylmethane (DDM) and 4,4′‐diaminodiphenylsulfone (DDS) were investigated by nonisothermal differential scanning calorimeter (DSC). The relationships of E_a with the conversion α in the curing process were determined. The catalyzed activation of hydroxyl group for curing reaction of epoxy resins with amine in DSC experiment was discussed. The results show that these curing reactions can be described by the autocatalytic ?esták‐Berggren model. The curing technical temperature and parameters were obtained, and the even reaction orders m, n, and ΔS for p‐BEPSBP/DDM and p‐BEPSBP/DDS are 0.35, 0.92, ?81.94 and 0.13, 1.32, ?24.45, respectively. The hydroxyl group has catalyzed activation for the epoxy–amine curing system in the DSC experiment. The average E_a of p‐BEPSBP/DDM is 67.19 kJ mol^?1 and is 105.55 kJ mol^?1 for the p‐BEPSBP/DDS system, but it is different for the two systems; when benzalcohol as hydroxyl group was added to the curing system, the average E_a of p‐BEPSBP/DDM decreases and increases for p‐BEPSBP/DDS. The crystalline phase had formed in the curing process and was fixed in the system. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Dynamic cure kinetics of epoxy/TiO2/MWCNT hybrid nanocomposites

The effect of multi-walled carbon nanotubes (MWCNTs) on cure kinetic parameters of the epoxy/amine/TiO₂ (1 wt%) resin system was studied dynamically at four heating rates using DTA. The presence of MWCNT in various amounts (0.1, 0.2, 0.4 and 0.6 wt%) neither retarded nor accelerated the cure reaction of the epoxy/amine/TiO₂ system in a considerable extent. Addition of MWCNTs increased the extent of cure of the corresponding nanocomposites, especially at higher contents up to 0.4 wt% MWCNT filled composite. However, increasing the MWCNT content to 0.6 wt% adversely affected the extent of cure due to nanoparticle agglomeration. The fracture surface morphology of the nanocomposites revealed that the cracks deviated on reaching the MWCNTs, while propagating in the polymer matrix. Fractional extent of conversion (α) was calculated using genetic algorithm. Flynn–Wall–Ozawa and Kissinger methods were used to analyze the kinetic parameters. The presence of MWCNTs did not affect the autocatalytic cure mechanism of epoxy/amine/TiO₂ resin system and also did not cause any considerable barrier effect on the curing process. Activation energy data fitted well in the cubic polynomial regression equations and the changes of E _a with respect to α proved the autocatalytic cure mechanism, being followed by all the MWCNT-containing epoxy-based hybrid nanocomposites.     

Curing kinetics and mechanical properties of fast curing epoxy resins with isophorone diamine and N-(3-aminopropyl)-imidazole

Fast curing epoxy resins were prepared by the reactions of diglycidyl ether of bisphenol A with isophorone diamine (IPD) and N-(3-aminopropyl)-imidazole (API), and their curing kinetics and mechanical properties influenced by IPD content were also investigated. The analysis of curing kinetics was based on the nonisothermal differential scanning calorimetry (DSC) data with the typical Kissinger, Ozawa, and Flynn–Wall–Ozawa models, respectively. The glass-transition temperature was also measured by the same technique. Additionally, the mechanical properties including flexural, impact, and tensile performances were tested, and the curing time was estimated by isothermal DSC. The degree of cure (α) dependency of activation energy (E_a ) revealed the complexity of curing reaction. Detailed analysis of the curing kinetics at the molecular level indicated that the dependence of E_a on the α was a combined effect of addition reaction, autocatalytic reaction, viscosity, and steric hindrance. From the nonisothermal curves, the curing reaction mechanism could be proposed according to the increasingly obvious low temperature peaks generated by the addition reaction of epoxy group with the primary amines in API and IPD molecules. Using the preferred resin formulation, the resin system could be cured within 10 min at 120 °C with a relatively good mechanical performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47950.     

Flame‐retardant properties and mechanisms of epoxy thermosets modified with two phosphorus‐containing phenolic amines

Two phosphorus‐containing phenolic amines, a 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO)‐based derivative (DAP) by covalently bonding DOPO and imine (SB) obtained from the condensation of p‐phenylenediamine with salicylaldehyde, and its analog (AP) via the addition reaction between diethyl phosphite and SB, were used to prepare flame‐retardant epoxy resins. The burning behaviors and dynamic mechanical properties of epoxy thermosets were studied by limited oxygen index (LOI) measurement, UL‐94 test, and dynamic mechanical analysis. The flame‐retardant mechanisms of modified thermosets were investigated by thermogravimetric analysis, Py‐GC/MS, Fourier transform infrared, SEM, elemental analysis, and laser Raman spectroscopy. The results revealed that epoxy thermoset modified with DAP displayed the blowing‐out effect during UL‐94 test. With the incorporation of 10 wt % DAP, the modified thermoset showed an LOI value of 36.1% and V‐0 rating in UL‐94 test. The flame‐retardant mechanism was ascribed to the quenching and diluting effect in the gas phase and the formation of phosphorus‐rich char layers in the condensed phase. However, the thermoset modified with 10 wt % AP only showed an LOI value of 25.7% and no rating in UL‐94 test, which was possibly ascribed to the mismatching of charring process with gas emission process during combustion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43953.     

Cure kinetics and conductivity of rigid rod epoxy with polyaniline as a curing agent

The samples of rigid rod epoxy resin (4,4′‐diglycidyl (3,3′,5,5′‐tetramethylbiphenyl) epoxy resin (TMBP)) with different weight contents of polyaniline (PANI) as a curing agent were prepared. The kinetics of curing reaction between TMBP and PANI was analyzed by dynamic differential scanning calorimetry in the temperature range of 25–300°C. The results showed that the heat of cure reaction of TMBP/PANI sample with 10 wt% PANI was larger than those of others. The active energies with different curing conversions of TMBP/PANI sample with 10 wt% PANI were calculated by iso‐conversional method using the Coats‐Redfern approximation. The results showed that the activation energy was dependent on the degree of conversion. The morphology of the cured samples was detected by scanning electron microscopy measurements. The relationship between morphology and conductivity of cured samples was researched. The conductivities increased from 2.7 × 10⁻⁴ to 9.5 × 10⁻⁴ S/cm with the increase of PANI from 5 to 20 wt% in cured samples. The thermal stabilities of cured TMBP/PANI samples were examined by thermogravimetric analysis. The results showed that the cured TMBP/PANI can be promising to use as a conducting adhesive. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Curing of diglycidyl ether of bisphenol‐A epoxy resin using a poly(aryl ether ketone) bearing pendant carboxyl groups as macromolecular curing agent

BACKGROUND: Reactive thermoplastics have received increasing attention in the field of epoxy resin toughening. This paper presents the first report of using a novel polyaryletherketone bearing one pendant carboxyl group per repeat unit to cure the diglycidyl ether of bisphenol‐A epoxy resin (DGEBA). The curing reactions of DGEBA/PEK‐L mixtures of various molar ratios and with different catalysts were investigated by means of dynamic differential scanning calorimetry and Fourier transform infrared (FTIR) spectroscopy methods. RESULTS: FTIR results for the DGEBA/PEK‐L system before curing and after curing at 135 °C for different times demonstrated that the carboxyl groups of PEK‐L were indeed involved in the curing reaction to form a crosslinked network, as evidenced by the marked decreased peak intensities of the carboxyl group at 1705 cm^?1 and the epoxy group at 915 cm^?1 as well as the newly emerged strong absorptions of ester bonds at 1721 cm^?1 and hydroxyl groups at 3447 cm^?1. Curing kinetic analysis showed that the value of the activation energy (E_a) was the highest at the beginning of curing, followed by a decrease with increasing conversion (α), which was attributed to the autocatalytic effect of hydroxyls generated in the curing reaction. CONCLUSION: The pendant carboxyl groups in PEK‐L can react with epoxy groups of DGEBA during thermal curing, and covalently participate in the crosslinking network. PEK‐L is thus expected to significantly improve the fracture toughness of DGEBA epoxy resin. Copyright © 2009 Society of Chemical Industry     

Durable flame‐retardant finished cotton fabrics characterized by thermal degradation behaviors

After a series of investigations on the durable flame‐retardant finishes, it was thought to be important to study these durable flame‐retardant finished materials from the thermal analytical standpoint. Accordingly, cotton fabric was finished with N‐methylol dialkyl phosphonopropionamide (Pyrovatex C) by thermofixation and tetrakis (hydroxymethyl) phosphonium sulfate (THPS) precondensate by ammonia cure (Proban), as well as with THPS monomer by heat cure under various conditions, and subjected to the thermogravimetry (TG) to observe thermal degradation behaviors and obtain apparent activation energy (E_a). TG curves of Proban‐finished samples showed the largest shift to lower temperatures with a steep slope; thermofixed THPS‐finished sample gave a smaller shift with similar steep slope, whereas Pyrovatex‐finished samples exhibited a similar shift but with a gradual slope. E_a versus residual ratio curves led us to conclude that C N bond‐rich Proban polymer requires the highest E_a and decomposes with considerable rapidity, whereas ethylene‐bond‐rich Pyrovatex‐finished samples with melamine crosslinking decompose gradually with the lowest E_a. As for the relationship between flame retardance and E_a distribution in the process of thermal degradation, typical differences among the above three kinds of finished samples were found, which are compared and discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 975–987, 1999     

Curing kinetics and thermal property characterization of the bisphenol‐F epoxy resin and phthalic anhydride system

The curing kinetics of bisphenol‐F epoxy resin (BPFER) and curing agent phthalic anhydride, with N,N‐dimethylbenzylamine as an accelerator, were studied by differential scanning calorimetry (DSC). Analysis of DSC data indicated autocatalytic behaviour in the first stages of the cure for the system, and that this, could be well described by the model proposed by Kamal, which includes two rate constants, k₁ and k₂, and two reaction orders, m and n. The curing reaction in the later stages was practically diffusion‐controlled. To consider the diffusion effect more precisely, a diffusion factor, ??(α), was introduced into Kamal's equation. The glass transition temperatures (T_gs) of the BPFER/phthalic anhydride samples were determined by means of torsional braid analysis. The thermal degradation kinetics of cured BPFER were investigated by thermogravimetric analysis. © 2002 Society of Chemical Industry     

The effects of polyamic acid on curing behavior,thermal stability,and mechanical properties of epoxy/DDS system

A thermoplastic modification method was studied for the purpose of improving the toughness and heat resistance and decreasing the curing temperature of the cured epoxy/4, 4′‐diaminodiphenyl sulfone resin system. A polyimide precursor‐polyamic acid (PAA) was used as the modifier which can react with epoxy. The effects of PAA on curing temperature, thermal stability and mechanical properties were investigated. The initial curing temperature (T_i) of the resin with 5 wt % PAA decreased about 50°C. The onset temperature of thermal decomposition and 10 wt %‐weight‐loss temperature for the resin system containing 2 wt % PAA increased about 60°C and 15°C respectively. Besides, the value of impact toughness and plain strain fracture toughness for the modified epoxy resin increased ～ 190% and 55%, respectively. Those changes were attributed to the outstanding thermal and mechanical properties of polyimide, and more importantly to formation of semi‐interpenetrating polymer networks composed by the epoxy network and linear PAA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Curing Behavior,Kinetics and Thermal Properties of o-Cresol Formaldehyde Epoxy Resin Modified by Liquid Crystalline Epoxy Resin

The curing kinetics of a bi-component system of o-cresol-formaldehyde epoxy resin (o-CFER) modified by liquid crystalline p-phenylene di[4-(2,3-epoxypropyl) benzoate] (p-PEPB), with 4,4-diamino-diphenyl ether (DDE) as a curing agent, was investigated by nonisothermal differential scanning calorimetry (DSC) method. The relationship between apparent activation energy, Ea, and the conversion α was obtained by the isoconversional method of Ozawa. A molecular reaction mechanism is proposed. The results show that the values of Ea in the initial stage are higher and tend to decrease slightly with the reaction progress. The primary amines have a higher Ea than secondary amines. The average curing Ea of o-CFER/p-PEPB/DDE system is 61.64 KJ/mol. These curing reactions can be described by a model proposed by ?esták and Berggren, which includes two parameters of m and n. Parameters such as reaction orders were evaluated using the ?esták-Berggren (S-B) equation and the following kinetic equation: dα/dt = Aexp(?Ea/RT)α ^m (1 ? a) ⁿ . The curing behavior of the system was studied by polarized optical microscopy (POM) and torsional braid analysis (TBA). The compatibility of the p-PEPB and o-CFER system is very good. Temperature of mechanical loss peak is higher by 63°C than the common o-CFER epoxy resin, when the weight ratio of p-PEPB with o-CFER is 4:100.     

Curing kinetics and thermal property characterization of o‐CFER/MeTHPA/O‐MMT nanocomposite

The kinetics of the cure reaction for a system of o‐cresol‐formaldehyde epoxy resin (o‐CFER), 3‐methyl‐tetrahydrophthalic anhydride (MeTHPA), N,N‐dimethyl‐benzylamine, and organic montmorillonite(O‐MMT) were investigated by means of X‐ray diffraction (XRD) and differential scanning calorimetry (DSC). The XRD result indicates that an exfoliated nanocomposite was obtained. The analysis of DSC data indicated the behavior was shown in the first stages of the cure for the system, which could be well described by the model proposed by Kamal. In the later stages, the reaction is mainly controlled by diffusion, and diffusion factor, f(α), was introduced into Kamal's equation. In this way, the curing kinetics was predicted well over the entire range of conversion. Molecular mechanism for curing reaction was discussed. The thermal degradation kinetics of the system were investigated by thermogravimetric analysis (TGA), which revealed that with the increase of O‐MMT content, TG curves shift to higher temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3023–3032, 2006     

Non-isothermal curing kinetics of epoxy/mechanochemical devulcanized ground rubber tire (GRT) composites

The curing behavior of diglycidyl ether of bisphenol A (DGEBA) epoxy and specially ground mechanochemical devulcanized ground rubber tire system (GRT) in the presence of polyoxyalkyleneamine curing agent was investigated by non-isothermal differential scanning calorimetry technique at different heating rates. Scanning electron microscopic-energy dispersive X-ray spectroscopy, and attenuated total reflection infrared spectroscopy were used to characterize the GRT particles. The kinetic parameters of curing process were determined by isoconversional method given by Málek. The average activation energy E _a was found to be 52.3–60.7 and 45–59.2 kJ/mol for neat epoxy amine (Epo am 31) and epoxy/amine with GRT (5 Epo am 31) systems, respectively. It was observed that the presence of GRT in epoxy/amine promotes the curing. A two parameter (m, n) autocatalytic model (SB equation) was found to be the most adequate to describe the cure kinetics of the studied epoxy/GRT system. A dominant catalyzing effect of GRT on the curing reaction was observed which is attributed to the complexity of the reaction at later stages of curing, therefore, it was not possible to model the reaction over the whole range of degree of conversion.