Mechanism Of Curing Reaction Research Articles

Adhesives Based on Poly(glycidyl methacrylate‐co‐butyl acrylate) with Controlled Structure: Curing Behavior and Adhesion Properties on Metal Substrates

AbstractThe adhesion properties of poly(glycidyl methacrylate (GMA)‐co‐butyl acrylate (BA)) statistical copolymers, synthesized by atom transfer radical polymerization (ATRP), are investigated employing three different curing agents or hardeners, such as diethanolamine (DEA), dicyandiamide (DICY), and 2‐cyanoacetamide (2‐CA) on copper, iron, brass, aluminum, and titanium metal surfaces. This work describes the treatment of the different surfaces, establishes the optimal curing conditions from differential scanning calorimetry (DSC) analysis of these novel adhesive systems, and evaluates the results of the single‐lap shear test for metal joints. Thus, by dynamic DSC measurements of the mixtures, a low curing temperature of 90 °C is defined when DEA is used as a curative; while systems based on DICY and 2‐CA require temperatures of 150 °C and 160 °C, respectively. In addition, the curing process of this controlled acrylic copolymer with DICY exhibits a singular behavior, possibly due to the curing reaction mechanism, where multiple epoxy‐amine ring‐opening polyaddition reactions take place between DICY's active hydrogens and epoxy groups of poly(GMA‐co‐BA). This latter curing system shows the highest adhesion features with lap‐shear strength at room temperature of 15.5 MPa, using copper as metallic substrate; however, the best results are obtained using 2‐CA as curing agent with aluminum and iron.

2D gradient and correlation FTIR analyses for optimizing thermal curing process of commercial-grade polyurethane coatings for automotive interior parts

Soft-feel coatings for automotive interior parts are a crucial factor in consumer purchase preferences owing to the growing awareness of human sensibility ergonomics. Herein, the thermal curing of commercial-grade polyurethane (PU) coatings was optimized using advanced spectroscopic tools. Conventional FTIR spectra were collected at various curing temperatures and times, and analyzed using two-dimensional (2D) gradient maps and 2D correlation spectroscopy (2D COS); while the former demonstrates the spectral variation trend with curing time, the latter provides whole spectral sequences that inform the cure reaction mechanism. The thermal curing continued for 50 min at 60 and 70 °C, and was halted after 30 min above 80 °C. According to the 2D COS and kinetic model fitting, the cure reaction was initiated by solvent evaporation and followed nucleation and growth mechanisms. PUs cured at lower temperatures were ductile owing to incomplete reactions, whereas PUs cured above 80 °C exhibited brittle features. Consequently, the optimal curing process was determined to be at 80 °C for 30 min. The 2D FTIR analytic tools can be useful in the development of high-quality soft-feel coatings for automotive interior parts.

A study on the characteristics of a novel inorganic solidified foam for the prevention and control of the spontaneous combustion of coal

• Response surface methodology was used to optimize formulation of solidified foam. • Mechanism of foaming and curing reaction of NICF was clarified. • Rice husk ash with high pozzolanic activity replaced fly ash. • Core parameters of the mixing device were determined by numerical simulations. The spontaneous combustion of coal seriously threatens the safe operation of coal mines. In order to solve the problems of the traditional inorganic solidified foam (TICF), i.e., a long gelation time, difficulty in uniform mixing, and low efficiency for blocking air leakage, a novel inorganic solidified foam (NICF) was proposed in this study to prevent the spontaneous combustion of coal; it was prepared by using rice husk ash (RHA), xanthan gum (GX), and sodium silicate (WG) as modifiers. Plackett-Burman experiments and response surface methodology were used to optimize the expansion ratio, stability coefficient, and gelation time of NICF and to determine the formulation of NICF in order to achieve rapid sealing of air leakage channels. A spiral hollow mixing device (SHMD) was developed based on the characteristics of NICF. The mixing effect of an aqueous foam (AF) and compound seriflux (CS) was numerically simulated by the ANSYS FLUENT software, and the SHMD parameters were determined with a high expansion ratio and uniform mixing of grout. The mechanism of the foaming and curing reaction of NICF and its mechanism for preventing the spontaneous combustion of coal were obtained by means of scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The experimental results indicated that WG hydrolyzed to produce an orthosilicic acid sol and sodium hydroxide in the process of particle hydration, and the sol could bind the particles to the hydration products. In addition, WG dissociated to generate a large amount of orthosilicate ions ([SiO 4 ] 4- ), which combined with the calcium ions present in a high concentration on the surface of the hydrated particles; this considerably reduced the gelation time of NICF. Ca 2+ on the surface of the hydrated particles chelated with the active functional groups such as the hydroxyl and carboxyl groups in GX, improving the compressive strength of NICF in the initial hydration stage. Compared with fly ash, rice husk ash has higher pozzolanic activity, and it undergoes a secondary hydration reaction with numerous calcium hydroxide crystals, increasing the hydration degree. This study can provide a theoretical basis for reducing the gelation time of NICF and explaining its foaming and curing reaction mechanism.

Curing and rheological study of epoxy molding compound with novel phosphonium silicate latent accelerators

AbstractLatent curing accelerators are significant for curing and molding controlling of epoxy molding compounds. Two novel phosphonium silicate latent accelerators, tetraphenylphosphonium bis(2,3‐dioxy‐naphthalene)methylsilicate (P‐Si‐Me) and tetraphenylphosphonium bis(2,3‐dioxy‐naphthalene)phenylsilicate (P‐Si‐Ph) were synthesized and characterized. The catalytic performance of P‐Si‐Me and P‐Si‐Ph on epoxy/phenolic resin system was evaluated and compared with commercial organophosphine accelerators triphenyl phosphine (TPP) and triphenylphosphine‐1,4‐benzoquinone (TPP‐BQ). Systems with four accelerators displayed similar autocatalytic curing reaction mechanism, and the curing and rheological behavior of four epoxy systems could be well described with the diffusion factor‐incorporated Kamal model, and Castro and Macosko model, respectively. DSC and rheology results showed that the latency of four accelerators followed the order of P‐Si‐Ph ≈ TPP‐BQ >> P‐Si‐Me > TPP, while the catalytic reactivity followed TPP > P‐Si‐Me > P‐Si‐Ph > TPP‐BQ. DMA results exhibited that epoxy systems with phosphonium silicate accelerators had higher Tg than that with TPP and TPP‐BQ. The latency and catalytic performance of phosphonium silicate accelerators were attributed to their ionic complex nature. Moreover, the substituent on silicate anion had obvious impact on the performance of accelerators.

Isoconversional models toward the curing kinetics of self‐healable epoxy resin TGDDM and acid anhydride

AbstractThe reaction process and curing mechanism of self‐healable epoxy resin TGDDM and curing agent TA are complicated. In this paper, the curing reaction kinetic mechanism of the system is studied from the perspective of isoconversional models. The nth‐order model and autocatalysis model are established for observations of heat flow versus temperature and time during real‐time curing obtained by non‐isothermal differential scanning calorimetry (DSC), and evaluated under the standards of MSE, RMSE, and R‐square. Under the guidance of least squares fitting, the pre‐exponential factor (A), the activation energy (), the order of models (n, m) and other parameters in of the model are mainly estimated by Kissinger method, Ozawa method, Malek method, and other methods. The correlation between the activation energy () of the reaction and the degree of conversion also analyzed by the Flynn‐Wall‐Ozawa method. The chemical reaction of the system is studied by Fourier transform infrared (FTIR) and the self‐healing property of the system is characterized by scanning electron microscope (SEM). It was found that the esterification reaction occurred in the system, and the realization of the self‐healing property was also due to the transesterification reaction. In addition, the effect of the accelerator on the system is analyzed by the established autocatalysis model and dynamic mechanical analysis (DMA). The result shows that the addition of the accelerator does not change the curing reaction mechanism of the system, but accelerated the reaction process and increased the glass transition temperature.

Curing mechanism and kinetics of benzoxazine co-catalyzed by transition metal salt and phenolic resin

• Curing kinetics of benzoxazine including PF and metalorganic compounds was studied. • The catalytic effect of phenolic resin and metalorganic compounds was explored. • The curing mechanism of benzoxazine including catalysts was studied. • Cure reaction model of different catalytic systems was determined by Malek method. Benzoxazine is widely used in halogen-free copper clad laminate, printed circuit board and other fields in electronic information industry. However, its high curing temperature (about 250 °C) limits its future application. The effectiveness of benzoxazine catalyzed by transition metal p -toluenesulfonate(M(OTs) n ) and linear phenolic resin(PF), separately and mixed, were studied by DSC. The curing mechanism, structural changes and curing kinetics of different catalytic systems was studied by In-situ FT-IR and nonisothermal Differential Scanning Calorimeter(DSC).The results show that M(OTs)n and PF can simultaneously exist in benzoxazine as catalyst, and the catalytic ability is the strongest. The kinetic data shows that the introduction of catalyst can change the curing reaction mechanism of benzoxazine from autocatalytic curing reaction model to n-order reaction model. It follows the n-order reaction kinetic model based on Malek and Friedman method, and the theoretical calculation curve is in perfect accordance with the experimental data.

Mechanism of Polyurethane Binder Curing Reaction and Evaluation of Polyurethane Mixture Properties

This study focuses on analyzing the curing reaction mechanism of polyurethane (PU) binders and comprehensively evaluating the PU mixture’s properties. The former was investigated by conducting a Fourier transform infrared spectroscopy (FTIR) test on PU binders with different curing times. The volume change characteristics, construction operation time, and strength formation law were clarified through the splitting tensile test of PU mixtures under different environmental conditions. The optimal PU mixture stacking time and curing time under different environmental conditions were determined. The properties of the PU mixture and asphalt mixture were evaluated and compared through a rutting test, low-temperature bending test, freeze–thaw splitting test, and four-point bending fatigue test. The results show that the physical and chemical curing of the PU binder occurred within the first 24 h of curing, and the reaction speed gradually accelerated to form a polyurea structure 24 h later. It is recommended to stack the PU mixture for 4 h before compaction and to cure it for 2 days before opening under the conditions of 50% humidity and 15–40 °C surrounding temperature. The PU mixture shows better temperature stability and fatigue resistance than the asphalt mixture, and the splitting tensile strength of the PU mixture before and after the freeze–thaw splitting test is also higher. It is clear that the PU mixture is a green road building material with good performance.

Curing Behavior of 4,4′-Diglycidyloxybiphenyl with p-Phenylene Diamine Derivatives

To expand the applicability of 4,4′-diglycidyloxybiphenyl (BP), the simplest liquid crystalline epoxy derivative, the curing reaction mechanism with p-phenylenediamine (p-PDA) derivatives under various stereoscopic conditions was investigated through kinetic analyses. Specifically, curing factors such as the starting temperature, heat, and activation energy were studied and analyzed. In particular, the effect of steric hindrance of the hardeners on the mechanism of curing reactions was explored by analyzing isothermal kinetics. It was found that the larger steric hindrance of the curing agents induced the slower curing reaction, and the contribution of the reduction in the self-catalytic curing was more pronounced than the SN2 reaction. To determine the optimized curing conditions, cured BP materials were fabricated and their glass-transition temperatures and thermal conductivities, which significantly improved over general-purpose epoxy resins owing to the characteristics of the liquid crystal, were investigated.

Corrosion resistance phosphate coating formed by steam assisted curing on cast Al[sbnd]Si alloy

In this work, a corrosion protection coating of aluminum phosphate (A-P) on cast Al-10% Si alloy was successfully prepared by dip coating and steam assisted curing method. The crystallization properties and microstructures of the A-P coating were determined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The result showed that the coating completely covered on the surface and exhibited excellent interfacial adherence with the substrate. The phase composition of the coating was mainly composed of AlPO4 and AlPO4·1.5H2O. The test results of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and the prolonged immersion time in 3.5 wt% NaCl solution revealed that the A-P coating showed a better corrosion resistance than original substrate. Furthermore, the mechanism of deposition and curing reaction of the A-P coating were proposed.

Curing Kinetics and Mechanism Research of E44/T31 Insulation Paint

Epoxy resin insulation paint was prepared with epoxy resin (E44) as binder and with proper inorganic fillers and curing agent (T31) as additives. The isothermal curing reaction process of paint was studied by the differential scanning calorimetry method (DSC), and the curves of curing reaction rate versus time of paint were obtained. The curing reaction kinetics was investigated by using the phenomenological method, and the corresponding parameters of the n-order model, autocatalytic model and Kamal model were determined by fitting the experimental data, respectively. According to the values of R2 and the sum of square due to error (SSE), a suitable curing reaction kinetic model was determined. The curing reaction mechanism of paint was ascertained by the dynamic temperature DSC method and IR spectroscopy (FTIR) method. The results show that the Kamal model can be used to describe the curing kinetics of epoxy resin paint, and the total reaction orders increase from 1.30 to 2.14. The two rate constants increase with the increase of the curing temperature. The activation energy is 90.5832 kJ/mol and 68.3733 kJ/mol respectively, and the pre-exponential factors are 6.521 × 1015 s-1 and 6.3807 × 109 s-1. The curing reaction of paint consists of two steps: the first step is the addition reaction of epoxy group and primary amine or secondary amine; the second step is the etherification reaction of epoxy group and phenolic hydroxyl or alcoholic hydroxyl.
 Epoxy resin insulation paint was prepared with epoxy resin (E44) as binders and with proper inorganic fillers and curing agent (T31) as additives. The isothermal curing reaction process of paint was studied by differential scanning calorimetry method (DSC), and the curves of curing reaction rate versus time of paint were obtained. The curing reaction kinetics was studied by using the phenomenological method, the corresponding parameters of the n-order model, autocatalytic model and Kamal model were determined by fitting the experimental data, respectively. According to the values of R2 and the sum of square due to error (SSE), a suitable curing reaction kinetic model was determind. The curing reaction mechanism of paint was ascertained by dynamic temperature DSC method and IR spectrogram (FTIR) method. The results show that the kamal model can be used to describe the curing kinetics of epoxy resin paint, the total reaction orders increase from 1.30 to 2.14. The results also show that the two rate constants increase with increasing curing temperature, The activation energies are 90.5832 kJ/mol and 68.3733 kJ/mol, and the pre-exponential factor are 6.521×1015 s-1 and 6.3807×109 s-1. The curing reaction of paint in two steps, the first step is the addition reaction of epoxy group and primary amine or secondary amine. The second step is the etherification reaction of epoxy group and phenolic hydroxyl or alcoholic hydroxyl.

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

ABSTRACTFast 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 (Ea) revealed the complexity of curing reaction. Detailed analysis of the curing kinetics at the molecular level indicated that the dependence of Ea 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.

Studies on Curing Kinetics and Tensile Properties of Silica-Filled Phenolic Amine/Epoxy Resin Nanocomposite.

In this study, the curing kinetics of the phenolic amine/epoxy resin system were investigated by nonisothermal differential scanning calorimetry (DSC). The model-free isoconversional method of Ozawa–Flynn–Wall reveals a dependence of Eα (activation energy) on conversion (α), which interprets the autocatalytic curing reaction mechanism of the phenolic amine/epoxy resin system. Studies on the effects of nano-SiO2 particles on the tensile properties and tensile fracture face morphology of nanocomposites show that the uniform dispersion of SiO2 nanoparticles plays an important role in promoting the tensile performance of nanocomposites. Additionally, increases of 184.1% and 217.2% were achieved by adding 1.5% weight parts of nano-SiO2 in composites for the tensile strength and tensile modulus, respectively.

Cure kinetics of modified lignosulfonate/epoxy blends

Epoxidized lignosulfonate (ELS) and cyclocarbonated lignosulfonate (CLS) were synthesized using modifying lignosulfonate. Through FTIR normalization procedure and titration method, the yield of epoxidation and carbonation were determined. Subsequently, two kinds of epoxy blends via the addition of ELS and CLS (20 wt%) as reactive fillers to a conventional DGEBA epoxy resin and curing by diaminodiphenylmethane (DDM) were prepared. The curing process was investigated by non-isothermal differential scanning calorimetry (DSC). For ELS/DGEBA and CLS/DGEBA blends and DGEBA epoxy resin, the curing kinetic parameters of Kamal model were computed via conventional fitting method using experimental reaction rate data. Also, through an approach proposed by Sbirrazzuoli, using activation energy data computed by an advanced integral isoconversional method developed by Vyazovkin, all samples exhibited a similar activation energy dependency on the extent of the reaction which can be attributed to a similar curing reaction mechanism for ELS/ DGEBA blend, CLS/ DGEBA blend and DGEBA.

Curing kinetics of liquid crystalline 4,4′-Diglycidyloxybiphenyl epoxy cured with 4,4′-Diaminodiphenylsulfone

Liquid crystalline epoxy resins (LCERs) have been reported as a promising polymeric material with a high thermal conductivity. Among them, 4,4′-diglycidyloxybiphenyl (BP) epoxy with the simplest molecular structure for the formation of a liquid crystal (LC) phase appears most suitable for practical applications. In particular, it is known that BP epoxy cured by 4,4′-diaminodiphenylsulfone (DDS) exhibits a high thermal conductivity of 0.34 W/m K; however, their detailed curing reaction mechanism and kinetics have not been reported yet. Herein, the detailed mechanism and kinetics of the curing reaction between BP and DDS are reported. The curing reactions in the temperature range of 150–230 °C are investigated with the mixed model of the nth order and autocatalytic mechanism. The reaction order (m and n), reaction rate (dα/dt), rate constant (k1 and k2), and degree of conversion (α) are analyzed at several temperatures, where subscripts 1 and 2 represent the nth order and autocatalytic reaction, respectively. The kinetic parameters, activation energy, and pre-exponential factor, were determined as Ea1 = 60.76 kJ/mol, Ea2 = 57.20 kJ/mol, A1 = 4.08 × 104 min−1, and A2 = 101.22 × 104 min−1, which are in good agreement with the experimental data. Furthermore, the kinetic data could be utilized to predict and control the curing behaviors and the properties of the LCER for further application.

Curing reaction mechanism and heat resistance properties of hexa‐(4‐carboxyl‐phenoxy)‐cyclotriphosphazene/bisphenol A aniline benzoxazine blends

ABSTRACTA blend system of hexa‐(4‐carboxyl‐phenoxy)‐cyclotriphosphazene (HCPCP) and bisphenol A aniline benzoxazine (BA‐a) was prepared, and its curing reaction mechanism and heat resistance properties were studied. The curing reaction mechanism of the blend was explored by differential scanning calorimetry, Fourier transform infrared spectroscopy, and modeling software using model compounds Ar‐COOH and hexachlorocyclotriphosphazene (HCCP). The heat resistance properties of the cured blends were studied by thermogravimetric analysis and dynamic mechanical analysis. The polymerization of benzoxazine was catalyzed by HCPCP through phosphazene ring and acid groups, and phosphazene played a predominant role. Compared with the materials with a single functional group (Ar‐COOH and HCCP), HCPCP containing two functional groups (phosphazene ring and acid) exhibited weaker catalytic effects, mainly due to the high molecular weight of HCPCP obstructing movement and causing steric hindrance. In addition, HCPCP had a positive effect on the thermal stability of polybenzoxazine from 250 to 400 °C. When the HCPCP content reached 3%, the cured blend had the highest glass‐transition temperature (222.2 °C), which is higher by 20 °C than that of cured benzoxazine. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46389.

Copolymerization of bisphthalonitrile/benzoxazine blends: Curing behavior, thermomechanical and thermal properties

A high-performance copolymer was successfully prepared by blending bisphenol-A based bisphthalonitrile monomer (BAPh) with phenol-aniline-based benzoxazine monomer (P-a). The obtained copolymers exhibited excellent thermal stability and thermomechanical properties. The Fourier transform infrared (FTIR) spectra of BAPh/P-a 5:5 system at different curing procedure proved the curing reaction mechanism. In addition, differential scanning calorimetry (DSC) curves showed that the curing reaction of the BAPh was induced by the active hydroxyl produced by the ring-opening polymerization of P-a; compared to the neat monomers, the curing temperature of the copolymer decreased and the curing speed improved. The evolution of thermal gravimetric analysis (TGA) curves revealed that the poly(BAPh/P-a)-5:5 displayed highest T5%, T10%, and char yield. The dynamic mechanical analysis (DMA) proved that the glass transition temperature and storage modulus of copolymers with the BAPh monomer as the matrix increased with the content of P-a increase, while copolymers with P-a as the matrix obtained nearly same results. The poly(BAPh/P-a) -5:5 exhibited best thermal and thermomechanical properties among different composition copolymers.

Thermokinetics behavior of epoxy adhesive reinforced with low viscous aliphatic reactive diluent and nano-fillers

The current study reports the effect of low viscous aliphatic reactive diluent (RD), MWCNT and VGCF on the curing kinetics of amine cured epoxy adhesive system employing non-isothermal differential scanning calorimetric (DSC) technique. Non-isothermal DSC thermograms of epoxy adhesive were studied at various heating rates: 5, 10 and 15 °C/min. The decrease in the exothermic peak height with the introduction of MWCNTs and VGCFs was taken as proof of the acceleration effect of nano-fillers on the epoxy-amine curing reaction. Also, increased T onset , T P and ΔH curs values were observed for epoxy/RD adhesive system at all heating rates. The value of activation energy (E a ) was determined using Kissinger and Flynn-Wall-Ozawa methods. Experimental results showed that the addition of 10 wt% RD increased the E a from 60 to 63 kJ/mol on account of the reduced viscosity, allowing better contact of resin with the curing agent. Furthermore, MWCNTs have an accelerating effect on the cure kinetics that does not change the autocatalytic cure reaction mechanism of epoxy resin. It was also found that the addition of MWCNT and VGCF decreases the overall degree of conversion, as evident with lower ΔH cure and E a of the cured adhesive when compared with epoxy/RD system. The dependency of E a on degree of conversion ranging from α =0.1 to 0.9was also investigated. The two normalized functions y(α) and z(α) were also considered in order to study the complex curing mechanism. The kinetic parameters m, n and lnA were obtained by using two parameter autocatalytic Sestak-Berggren model. The curves revealed good agreement between experimentally determined and theoretically obtained MWCNT/VGCF reinforced epoxy adhesive systems.

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

ABSTRACTFurfuryl 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 [Eα, Aα, and f(α)] were computed by using an integral isoconversional method. Based on the Eα‐dependency results a single‐step autocatalytic model was suggested for the reactions mechanism, however, the Aα‐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.

Effects of compound curing agent on the thermo-mechanical properties and structure of epoxy asphalt

Epoxy asphalt curing system was prepared by sebacic acid compound with methyl-tetrahydrophthalic anhydride (MeTHPA) or Tung oil anhydride (TOA). Tensile strength, penetration, differential scanning calorimetry, dynamic mechanical thermal analysis, torn section microscopy photographs and scanning electron microscope analysis were utilised to investigate the mechanical properties, thermodynamic behaviour and micro-structure of epoxy asphalt curing systems under different curing agents. The results showed that in the presence of compound curing agent, the tensile strength and surface hardness of the epoxy asphalt curing system effectively improved, the induction period of the curing reaction decreased, the curing reaction mechanism turned to one-step reaction from two-step reaction, the Tg of asphalt phase and epoxy phase could simultaneously increase, and high-temperature damping performance also improved, but the particle size of asphalt dispersed in epoxy resin becomes uneven, while the curing system becomes semi-brittle from toughness. Compared to TOA, the effects of MeTHPA on such performance were more obvious.

Effects of Different Montmorillonite Nanoclay Loading on Cure Behavior and Properties of Diglycidyl Ether of Bisphenol A Epoxy

The primary focus of this study was to understand the effects of different amounts of montmorillonite nanoclay (MMT) loading on viscosity, cure behavior, reaction mechanism, and properties of diglycidyl ether of bisphenol A (DGEBA) epoxy composites. Influence of 1–3 wt.% MMT on rheological and subsequent cure behavior of SC-15 epoxy resin was studied using nonisothermal and isothermal rheometry and differential scanning calorimetry (DSC). Rheological properties were influenced by different amounts of MMT at lower shear rates prior to and during curing. Cure reaction mechanism was unaffected by different MMT concentration; however heat and activation energy of reactions increased with increasing MMT loading. Samples with 2 wt.% MMT showed highest reaction rate constant, indicative of catalytic behavior. X-ray diffraction (XRD) and transmission electron microscope (TEM) revealed mainly intercalated microstructure throughout the MMT infused epoxy composite samples irrespective of the percent loading.