Tetraglycidyl Diaminodiphenyl Methane Research Articles

Influence on organic inorganic hybrid (mullite) fibre on mechanical, thermo-mechanical and morphological properties of TGDDM epoxy nanocomposites

ABSTRACT The objective of the present work is to synthesise N,N’-tetraglycidyldiaminodiphenylmethane (TGDDM) epoxy resin via 4,4ʹ-diaminodiphenylmethane (DDM) and epichlorohydrin in order to obtain tetra-functional epoxy with improved properties. The molecular structure of TGDDM epoxy resin was confirmed from fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectral data. Theamine functionalised mullite fibre (F-MF) was synthesised through using 3-aminopropyltriethoxysilane as a coupling agent to prepare amino groups on the surface mullite fibreand its structure confirmed with FTIR. The TGDDM epoxy resin was reinforced with variant weight percentages (1–3 wt%) of F-MF nanocomposite was cured with DDM. The morphology of TGDDM and nanocomposites was examined using X-ray powder diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscope (SEM). .We observed improvement in properties of thermal, thermo-mechanical, mechanical, di-electric constant and water absorption behaviour of TGDDM epoxy nanocomposites.

Construction of Novel Proton Transport Channels by Triphosphonic Acid Proton Conductor-Doped Crosslinked mPBI-Based High-Temperature and Low-Humidity Proton Exchange Membranes

High proton conductivity and sufficient stability of the polybenzimidazole membrane are important for the application of high-temperature proton exchange membrane fuel cells (HT-PEMFCs). A series of composite membranes based on crosslinked mPBI (cPBI) with cerium 2,4,6-triphosphono-1,3,5-triazine (CeTPT) were resoundingly fabricated. Novel cPBI networks with tetrafunctional N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) were synthesized. It is noteworthy that a new high-temperature proton conductor CeTPT was added. CeTPT contained three phosphonic acid groups, which offered good proton conductivity at moderate-to-low humidity and had good thermal stability. Tetrafunctional crosslinker TGDDM had multiple functional groups. With a relatively low crosslinking degree (CLD), the mechanical properties, dimensional stability, and oxidative resistance of the membranes were efficiently improved. The low CLD and good physicochemical stability also allowed high doping levels of CeTPT (up to 50%) and consequently high proton conductivity. At 180 °C and 50% RH, the proton conductivity of cPBI-5-CeTPT-50 and cPBI-10-CeTPT-50 was 0.072 and 0.068 S cm–¹, respectively. The cPBI-CeTPT membranes showed good methanol resistance and membrane selectivity, and thus the membranes were suitable for direct methanol fuel cells.

Study of the acoustic emission response to a core-shell rubber-toughened, high-temperature composite

This work explores the effect of core-shell rubber (CSR) addition on the cure reaction and resulting mechanical and thermal properties of a highly cross-linked network made from 4,4′- tetraglycidyl diamino diphenyl methane and 3,3′-diamino diphenyl sulphone. Up to 20 wt% of a CSR rubber, composed of a soft polybutadiene core and a hard poly methyl methacrylate (PMMA) shell was dispersed in the epoxy/amine and after cure was found to increase the glass transition temperature and thermal degradation temperatures modestly, while reducing the char yield. Flexural properties also reduced with CSR addition, although fracture toughness (KIC) was increased by 45% at 20 wt% of CSR. Furthermore, the fracture strain energy release rate (GIC) of the corresponding carbon fibre composite at the same CSR concentration, increased by almost 115%. Acoustic emission spectroscopy is introduced as a tool for investigating crack propagation during mode I loading and identifying any differences in the failure mechanism between the unmodified and the 20 wt% CSR-modified carbon fibre composites.

Bonding mechanism on TGDDM/CF and the influences of functional groups and interfacial water: An MD and DFT investigation

Bonding mechanism between tetraglycidyl diamino diphenyl methane (TGDDM) epoxy resin and carbon fiber (CF) is investigated by employing MD and DFT methods. Edge sites of CF surface (CF(100) and (110)) are focused due to they are chemically active than the inert basal planes. Two kinds functional groups (OH and COOH) are anchored on these sites, and the impacts of interfacial water are examined. The most negative adsorption energy (Ead) goes to the model of TGDDM absorbed onto COOH-functionalized CF(110) (noted as CF(110)COOH). Mulliken population analysis implies that O-H hydrogen bonds have formed across the interface. More bonds tend to form with CF(110) surface and COOH groups. The energy per each hydrogen bond is around 25.95–31.07 kJ/mol, and bond length ranges around 1.81–2.49 Å, which are consistent with previous reports. For the interfacial bonds associated with OH-functionalizaion, TGDDM and OH groups are hydrogen acceptors and donors, respectively. While for the cases with COOH groups, both the TGDDM and COOH groups can act as either acceptors, or donors. Caused by interfacial water, the interfacial hydrogen bonds will be detached, and the interaction energy (Eint) between TGDDM-CF(110) decreases 84.04%. Meanwhile, new hydrogen bonds will form between H2O-TGDDM (and H2O-CF).

Composition optimization of a high-performance epoxy resin based on molecular dynamics and machine learning

Epoxy resin is a general term for a class of thermosetting polymers containing two or more epoxy groups in the molecule and has an excellent comprehensive performance. The properties of the resin system vary greatly due to the different compositions of the base resin, curing agent, and toughening agent. In this study, an optimization method for the multi-component epoxy resin system was put forward by using molecular dynamics simulations and machine learning methods. An optimized high- performance epoxy resin system considered Young's modulus (E), Ultimate Tensile Strength (UTS), Elongation (δ), and the glass transition temperature (Tg) together was designed by using the proposed method. The influence of each component proportion on mechanical properties can also be obtained automatically. It was found that 4,4′-Diaminodiphenyl Sulfone (DDS) was a better curing agent to improve Tg, E, and δ, compared with Dicyandiamide (DICY). Tetraglycidyl Diamino Diphenylmethane (TGDDM) could ensure high Tg, E and UTS, but the system still needed some Diglycidyl Ether of Bisphenol A (DGEBA) to improve toughness. The toughening agent Polyether Sulfone (PES) improved the toughness of the epoxy resin system significantly. The presented method could be extended to other resin system composition optimization.

Tertiary‐amine‐free, non‐planar, sulfone‐containing, tetrafunctional epoxy and its application as a high temperature matrix

AbstractNon‐amine‐derived tetrafunctional epoxies have several advantages over the amine‐derived N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenyl methane (TGDDM) in high temperature applications. Although two non‐amine‐derived tetrafunctional epoxies were developed in our laboratory, further improvements in toughness using less loading amount is still desirable. Thus, a tertiary‐amine‐free, non‐planar and triphenylmethane‐containing tetrafunctional epoxy (STFE) with a sulfone spacer was synthesized. When it was mixed with diglycidyl ether of bisphenol A (DGEBA) and cured with 4,4′‐diaminodiphenylsulfone (DDS), both thermal and mechanical performances outperformed TGDDM. Moreover, STFE modified system shows the highest toughness (35.7 kJ m–2) among three amine‐free and triphenylmethane‐containing epoxies at merely 5 wt% loading. Molecular simulation and thermomechanical analysis results suggest that the improved mechanical properties could be related to the geometry of the molecule and larger free volume. Despite a marginal drop in Tg, the thermal degradation temperature is better than that of TGDDM/DDS. In addition, the moisture resistance of STFE/DGEBA/DDS is much better than that of TGDDM/DDS. Thus, STFE modified DGEBA could be a potential replacement for TGDDM in some high temperature applications. © 2020 Society of Chemical Industry

Internal stress analysis of epoxy adhesively‐boned joints based on their thermomechanical properties at cryogenic temperature

AbstractInternal stress analysis is essential to structural design of materials applied in cryogenic engineering. In this contribution, thermomechanical properties including dynamic thermomechanical properties and thermal expansion behavior of four epoxy resins, namely the polyurethane modified epoxy resin (PUE), diglycidyl ether of bisphenol A (DGEBA), tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM) and triglycidyl‐p‐aminophenol (TGPAP) were studied by dynamic thermomechanical analysis. Internal stress of the epoxy layer in the bonded joint was calculated based on the thermomechanical properties. Meanwhile, the structure‐cryogenic property relationship of epoxy resins were investigated. Results demonstrate that internal stress in the four epoxies bonded joints is 6 ~ 21 MPa at −150°C, and is positively correlated with the average thermal expansion coefficient (CTE) of epoxy resins. TGDDM and TGPAP showed higher retention of lap shear strength both at −196°C and after temperature cycling due to their lower CTE. Morphology of the fractured surface of bonded joints demonstrated that internal stress is responsible for the severe interface failure at −196°C. It reveals that selection of epoxy resins with low CTE is beneficial for designing high‐performance epoxy adhesive systems served at cryogenic temperature.

Thermoset modified with polyethersulfone: Characterization and control of the morphology

AbstractThermoset (TS) epoxy resins can be toughened with a thermoplastic (TP) for high‐performance applications. The final structure morphology has to be controlled to achieve high mechanical properties and high impact resistance. Four polyethersulfone‐modified epoxy resins are considered. They consist of different epoxy monomer structure (TGAP, triglycidyl‐p‐aminophenol and TGDDM, tetraglycidyl diaminodiphenylmethane) and a fixed amount of thermoplastic, and they are cured with two different amounts of curing agent. A reaction‐induced phase separation occurs for all formulations generating morphologies, different in shapes and scales. The aim is to control the final morphology and in particular its dominant length scale. This morphology depends on the phase separation process, from the initiation to its final stage. The initiation relies on the relative miscibility of the components and on the stoichiometry between epoxy and curing agent. The kinetics depends on the viscosity of the systems. The different morphologies are characterized by electron microscopy or neutron scattering. Dynamic mechanical analysis allows confirming the presence of a phase separation even when it is not observable by electron microscopy. Vermicular morphologies with few hundreds nanometer width are obtained for the systems containing the TGAP as epoxy monomer. Systems formulated with TGDDM presents morphologies on much smaller scale of order a few tens of nanometers. We interpret the different sizes of the morphologies as a consequence of a larger viscosity for the TGDDM systems as compared to the TGAP ones rather than by a latter initiation of phase separation.

Novel phosphorus-containing imidazolium as hardener for epoxy resin aiming at controllable latent curing behavior and flame retardancy

One-pack flame-retardant epoxy resins (EP) with long pot life before using, high curing activity during operating and satisfactory fire safety after curing are extremely needed in electrical & electronics and composite industries. Here, imidazolium diphenylphosphinate (IDPP) was designed and synthesized by a facile way, thereafter used as a hardener for diglycidyl ether of bisphenol A type EP (DGEBA). IDPP/DGEBA possessed long-term stability in liquid state at ambient temperature while cured rapidly under heating, presenting controllable latent curing behavior relying on temperature. Specific phosphorus-containing groups were finally attached to epoxy chains mainly by ionic bonds, thus slightly affected the network structures of the resins. Consequently, the cured EP simultaneously achieved high glass transition temperature (Tg), good thermal stability, excellent flame retardancy and expected dielectric performance. Especially, with only 15 wt% IDPP incorporated, the cured DGEBA exhibited a high Tg (172.7 °C), low dielectric constant (4.00) and loss (0.004) at 10 MHz respectively, and easily achieved UL-94 V-0 rating with a high limiting oxygen index (37.0%). The data obtained from cone calorimetry indicated the flammability of the resins was significantly suppressed when cured with IDPP. It was verified by thermogravimetric analysis/infrared spectrometry that IDPP showed dominating vapor-phase flame-retardant effect in DGEBA systems. Additionally, IDPP was also qualified as a latent hardener for tetraglycidyl diaminodiphenylmethane (TGDDM) with excellent thermal stability and flame retardancy.

A molecular dynamics study on heat conduction of crosslinked epoxy resin based thermal interface materials for thermal management

The epoxy resin is one of important thermal interface materials which can reduce thermal contact resistance of microelectronic devices. In the interest of relation between heat conduction and crosslinks, the thermal conductivities of epoxy resins modeled with N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenyl methane (TGDDM) and three types of diamine crosslinkers, i.e. 1,3-benzenediamine (MPD), 3,3′-diaminodiphenyl sulfone (3,3′-DDS) and 4,4′-diaminodiphenyl sulfone (4,4′-DDS), have been calculated by performing reverse non-equilibrium molecular dynamics simulations (NEMD). In order to interpret the change of thermal conductivity, the auxiliary equilibrium molecular dynamics simulations (EMD) have been carried out to calculate the density, hydrogen bond number/lifetime, radial distribution function, diffusion coefficient and potential energy as well as its components. And the effects of types of crosslinkers, crosslinked density and temperature on the structure, inter/intra-molecular interactions and dynamic properties of the epoxy resin were then analyzed. Generally, the short-skeleton crosslinkers, crosslinkers with fewer elements, higher crosslinked density and higher temperature will contribute to the enhancement of thermal conduction. And the crosslinks and enhanced non-bonded interaction both contribute to the increase of thermal conductivity. The present paper elucidates the relation between heat conduction and molecular structures for the crosslinked epoxy resin.

Atomic oxygen degradation mechanisms of epoxy composites for space applications

The effects of atomic oxygen on three commercial composite materials, based on two space-qualified epoxy resins (tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) cured with a blend of 4,4′-methylenebis(2,6-diethylaniline) and 4,4′-methylenebis(2-isopropyl-6-methylaniline); and a blend of TGDDM, bisphenol A diglycidyl ether (DGEBA), and epoxidised novolak resin initiated by N’-(3,4-dichlorophenyl)-N,N-dimethylurea) are studied. Samples were exposed to a total fluence of (3.82 × 1020atom/cm2), equating to a period of 43 days in low Earth orbit. The flexural rigidity and modulus of all laminates displayed a reduction of 5–10% after the first exposure (equivalent to 20 days in orbit). Fourier transform infrared (FTIR) spectra, obtained during prolonged exposure to atomic oxygen, were interpreted using multivariate analysis to explore the degradation mechanisms.

The effect of nanoalumina silanisation in tetraglycidylether epoxy adhesive

The efficiency of different surface modifications on alumina nanoparticles on both filler dispersion and the final properties of the resulting adhesive nanocomposites have been investigated. A tetraglycidyldiaminodiphenylmethane (TGDDM) epoxy resin and three sample series of nanocomposites were prepared via in-situ incorporation of alumina nanoparticles into the reactor. The alumina/TGDDM nanocomposites were prepared individually using neat or non-treated alumina nanoparticles and two kinds of silane-grafted alumina nanoparticles, i.e., APS-treated alumina and GPS-treated alumina. The presence of different alumina nanoparticles in the epoxy matrices resulted in different states of nanofiller dispersion as revealed in SEM and AFM micrographs. It was elucidated that the silane treatment on alumina nanoparticles is crucial for the desired dispersion in the epoxy matrix. Besides, the appropriate filler dispersion resulted in improved thermal resistance and high degree of cure, especially for the adhesive nanocomposite containing APS-treated alumina nanoparticles. In adhesion tests, the shear strength was improved in both nanocomposites containing silane-grafted alumina with more pronounced values for the nanocomposite containing APS-treated alumina nanoparticles. The shear strength reached from 6.6 MPa for the neat epoxy adhesive to 10.2 MPa for the adhesive nanocomposite containing 5 wt % APS-treated alumina nanoparticles mainly due to high levels of dispersion of the high modulus alumina nanoparticles and effective interfacial interactions with the epoxy matrix. The adhesive peel strength of alumina/TGDDM nanocomposites showed a similar trend as in shear strength with more pronounced variations. A noticeable increase in the peel strength of the nanocomposites containing silane-grafted alumina nanoparticles appeared to correlate with greater levels of crack deflection and hence dissipation of fracture energy as observed in SEM pictures.

Analysis of high melt‐strength poly(ethylene terephthalate) produced by reactive processing by shear and elongational rheology

Three grades of poly(ethylene terephthalate) (PET) produced by different synthesis routes and with different molar masses were reactively extruded with two tetra‐functional chain extenders, i.e., pyromellitic dianhydride (PMDA) and tetraglycidyl diamino diphenyl methane (TGDDM). The preferred reactivity of the coupling agents led to different long‐chain branched (LCB) structures, which can be related to different hydroxyl and carboxyl end group concentrations of the PET grades investigated. The complex viscosity and the transient elongational viscosity increased by up to two decades. Both the activation energy of flow and the loss angle indicate long‐chain branching. A more quantitative assessment of the extent of strain hardening was achieved by application of the molecular stress function (MSF) model. The two material parameters of the model revealed different behaviors depending on the chain extender used. The initial molar mass of PET and the concentration of end groups, i.e., hydroxyl and carboxyl, determine the structure of the polymer molecules. PMDA proved to be an excellent coupling agent for industrial processing which induces reproducibly either a star‐like, comb‐like, or randomly branched structure depending on the concentration of coupling agent added and the hydroxyl concentration of the PET employed. TGDDM led to a hyperbranched structure. POLYM. ENG. SCI., 59:396–410, 2019. © 2018 Society of Plastics Engineers

Tertiary-amine-free, non-planar, fluorine-containing tetrafunctional epoxy and its application as high performance matrix

N,N,N′,N′-tetraglycidyl-4,4′-diamino-diphenylmethane (TGDDM) is the most widely used epoxy matrix in aerospace/aircraft industries, however its cured product suffers from cyclization side reactions, inadequate toughness and water resistance, and relatively high dielectric constant, which are rooted in its amine-derived nature. In order to address those issues, a tertiary-amine-free, non-planar, fluorine-containing tetrafunctional epoxy (FCTE) was synthesized with high yield. When FCTE is mixed with DGEBA and cured with 4,4′-diaminodiphenylsulfone (DDS), the cured epoxy shows excellent balanced properties. At 20 wt% FCTE loading, the cured mixed epoxy shows a tensile strength and impact strength of 82.5 MPa and 30.5 kJ/m2, respectively, which are higher than those of TGDDM (76.5 MPa and 11.6 kJ/m2). Molecular simulation, PALS measurement, and TMA characterization suggest that the improved mechanical properties could be related to the marginal side reactions and larger free volume. The introduced fluorine-containing units also lead to better water resistance and lower dielectric constant compared with TGDDM. Despite a marginal drop in Tg, thermal degradation temperature is greatly improved. In addition, when FCTE is used as the matrix for a polyimide fiber reinforced composite, the interlaminar shear strength is also higher, making it a better candidate for preparing high temperature, light weight, and low-k composites.

The mechanical behaviors of epoxy-terminated hyperbranched polyester (E-HBP) as toughener in different epoxy resins

Using epoxy-terminated hyperbranched polymer (E-HBP) to modify epoxy resin (EP) is an effective way to improve the toughness of EP. In the present study, two different epoxy resin systems with E-HBP are researched: a commercial diglycidyl ether bisphenol A (DGEBA) resin with anhydride as curing agent and a tetraglycidyl diaminodiphenyl methane (TGDDM) resin with diamine as curing agent. Characterization results show that the addition of E-HBP could improve the mechanical properties of the two epoxy resin systems, such as tensile strength, elongation, and modulus of elasticity. Meanwhile, the glass transition temperature (T g ) of the two systems does not decrease. However, the morphology of the tensile fracture surfaces of the two modified systems shows different behaviors. Significant plastic deformation could be observed in the fracture surfaces of the modified DGEBA/anhydride system, and particle cavitations are clearly shown in the fracture surfaces of the modified TGDDM/diamine systems. The analysis of the tensile fracture surfaces suggests that firstly E-HBP participates in the curing process of the modified resin systems, followed by the chemical-induced phase separation; finally, a gradient transition interface layer (GTIL) is formed. Apart from these, during the external loading process, the mechanical behaviors (deformation or cavitation) of the separated E-HBP particles in the modified epoxy resins are affected by the properties of the epoxy matrix itself.

Property improvements of thermoplastic copolyester with a multifunctional mixture/nanofiller by reactive extrusion

ABSTRACTThe approach of processing reactive functional nanofillers into thermoplastic copolyester (TPE‐E) using reactive extrusion (REX) has been explored. The mixing of a hydroxyl‐bearing organo‐fluoromica combined in toluene with a tetraglycidyl‐4,4‐diamino‐diphenylmethane (TGDDM) led to the intercalation of the TGDDM molecule into the interlayer space. Subsequent REX work involved processing TPE‐E with 0.3% (w/w) TGDDM and 2% (w/w) organoclay in a twin‐screw extruder. It is demonstrated that the effects of the modification route to control morphology on the nanoscale could be systematically investigated. The hard segment acted as a physical crosslink, imparting elastomeric properties on the soft segment. Increases seen in creep resistance and reduction in the water vapor transmission rate of TPE‐E proved that the reactive organo‐fluoromica was able to promote enhanced dimensional stability and barrier properties of TPE‐E. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46369.

Rheological and molecular characterization of long-chain branched poly(ethylene terephthalate)

Reactive extrusion with pyromellitic dianhydride (PMDA) and tetraglycidyl diamino diphenyl methane (TGDDM) was conducted to create long-chain branched poly(ethylene terephthalate) (LCB-PET). The mechanical and molecular properties were analyzed by linear and non-linear viscoelastic rheology in the melt state and by size-exclusion chromatography measurements with triple detection. The two tetra-functional chain extenders lead to strong viscosity increases, increasing strain hardening effects, and increasing LCB with increasing chain extender concentration. Molecular stress function model predictions show good agreement with the elongational data measured and allowed a quantification of the strain hardening. Analysis of SEC triple detection data shows a strong increase of the average molar mass, polydispersity, radius of gyration, and hydrodynamic radius with increasing chain extender concentration. Branching was confirmed by a decreasing Mark-Houwink exponent, and the analysis of the contraction of the molecule revealed either star-like, comb-like, random tree-like or hyperbranched structures depending on concentration and type of chain extender.

Nitrogen-Free Tetrafunctional Epoxy and Its DDS-Cured High-Performance Matrix for Aerospace Applications

Tetrafunctional epoxy is an indispensable matrix for the aerospace industry, high-temperature adhesives, and encapsulation materials, where high service temperatures (>220 °C) are required. N,N,N′,N′-Tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) has long been the dominant candidate in those applications; however, fully cured TGDDM epoxy materials suffer from poor toughness, unwanted side reactions, and inadequate moisture resistance. A novel tetrafunctional epoxy, TFTE, is synthesized to address those issues, which have not been resolved for decades. TFTE can be prepared through a simple three-step procedure using readily available raw materials. Each step shows a high yield (>90%) and involves only mild reaction conditions. When TFTE is mixed with diglycidyl ether of bisphenol A (DGEBA) and cured with 4,4′-diaminodiphenylsulfone (DDS), the cured epoxy shows a Tg value of 252 °C, a tensile strength of 80.0 MPa, and, more importantly, a higher toughness (29.8 kJ/m2) and better moisture resistance than ...

Non-isothermal cure and decomposition kinetics of epoxy–imidazole systems

Non-isothermal curing kinetics of a tetra functional epoxy resin with imidazole-based curing agents was investigated by differential scanning calorimetry (DSC), and decomposition of the cured compounds was studied by thermogravimetric analysis. N,N,N′,N′-tetraglycidyl-4, 4′diaminodiphenylmethane (TGDDM) was cured with three types of tertiary amine curing agents including 1-methyl imidazole (MI), 2-methyl imidazole (2MI) and 2-ethyl 4-methyl imidazole (EMI). These systems exhibited cure initiation at around 70–90 °C by DSC. 2-methyl imidazole and 2-ethyl 4-methyl imidazole showed two cure initiation profiles, while the 1-substituted counterpart, MI, showed a single cure initiation profile by DSC. The Kissinger equation was applied to calculate the apparent activation energy for epoxy–imidazole cure reactions. The rate constants and the pre-exponential factor were also determined. The activation energy varied from 59 to 65 kJ mol−1 for the systems. The Flynn–Wall–Ozawa iso-conversional approach was used to elucidate the activation energies at different extents of conversion during the cure reactions. The cured systems are found thermally stable up to 250 °C. Decomposition kinetics of cured networks was studied using Kissinger equation and Flynn–Wall–Ozawa iso-conversional approach. The cured resins were analyzed for the glass transition temperature and compared with that of a conventional amine-cured system.

Morphologies and mechanical properties of polyethersulfone modified epoxy blends through multifunctional epoxy composition

ABSTRACTThermoplastic polyethersulfone (PES) modified multifunctional tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM) and triglycidyl para‐aminophenol (TGAP) epoxy prepolymers cured with 4,4′‐diaminodiphenylsulfone (44DDS) were prepared using a continuous reactor method and their reaction‐induced phase separated morphologies and mechanical properties were measured and correlated with chemical compositions. 1H nuclear magnetic resonance (1H NMR) and near‐infrared spectroscopy (NIR) were used to quantify the chemical network formation. Atomic force microscopy (AFM) with nanomechanical mapping was employed to resolve the nanoscale phase‐separated morphologies. The extent of phase separation in cured networks and resultant domain sizes were determined to be controllable depending upon the multifunctional epoxy compositions. The results obtained from mechanical studies further indicated that tensile modulus was not largely affected by multifunctional epoxy compositions while fracture toughness increased with increase of TGAP content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44775.