Tetraglycidyl Diaminodiphenyl Methane Research Articles

The effects of two-step reactive processing on the properties of recycled poly(ethylene terephthalate)

A simple approach for preparing recycled poly(ethylene terephthalate) (r-PET) with excellent processability and melt strength has been developed in this research. To increase the intrinsic viscosity of r-PET, a two-step chain extension process using a combination of SAG-008 and tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) was investigated. To evaluate the chain extension degree of the modified r-PET, its intrinsic viscosity (IV) and rheological properties were characterized, and found to be correlated to the long-chain branches and molecular weight. The results indicated that the combination of SAG-008 and TGDDM at the optimized conditions provided the highest IV of 1.18 dl/g while controlling the gel formation to a low value. The increases in storage modulus, loss modulus and complex viscosity revealed the enhancement of melt strength and viscoelasticity of r-PET. The differential scanning calorimetry results showed that the crystallinity was reduced with the addition of chain extenders. On the other hand, stepwise annealing method from room temperature to crystal melting temperature promoted the crystallization, which was confirmed by wide-angle X-ray diffraction measurement.

Synthesis and characterization of the nano alumina-filled tetraglycidyl-4, 4′-diaminodiphenylmethane epoxy resin

In this study, the in situ incorporation of the inorganic alumina nanoparticles into the reactants of tetraglycidyl-4, 4′-diaminodiphenylmethane (TGDDM) epoxy resin represented an efficient way for the preparation of alumina/TGDDM nanocomposite. The surface modification of the alumina nanoparticles was carried out using two individual silane coupling agents, namely, aminopropyltriethoxysilane (APS) and glycidoxypropyltrimethoxysilane (GPS). The degree of silane grafting was evaluated for both coupling agents using FTIR spectroscopy and thermogravimetric analysis. The epoxy equivalent weight (EEW) of the epoxy resin in addition to the weight percentage of the lost nanoparticles during TGDDM polymerization was used as measurements of the polymerization yield. The neat nano alumina has more adverse effect on the epoxy EEW value (171 g/mol) than both silane-modified nano alumina (143–157 g/mol, depending on the reaction conditions). The degree of nano alumina dispersion in the epoxy matrix was investigated using SEM micrographs. The longer and more deflected crack pathways on the fractured surface of the alumina/TGDDM nanocomposites may be attributed to a relatively good degree of dispersion of the silane-modified alumina nanoparticles in the epoxy matrix. Compared to neat alumina, the better dispersion of the silane-modified alumina nanoparticles may be related to the improved interfacial interactions between the oxiran or amine groups available on the silane-modified alumina nanoparticles and the TGDDM epoxy functional groups. Besides, the higher exothermic heat of cure (i.e., 30–53 %) as evidenced in differential scanning calorimetry may be due to a rather good state of dispersion of silane-modified alumina nanoparticles.

The network structure and properties of multifunctional epoxy/anhydride systems

In this study, bi-, tri-, and tetra-functional epoxy systems were chosen to design network structures using hexahydrophthalic anhydride as curing agent and tris-(dimethylaminomethyl) phenol as accelerant with bifunctional 1,4-butanediol diglycidyl ether as the flexible reactive diluents to further adjust the network structure. The cross-link density and activation energy ( Ea) of glass transition were calculated by dynamic mechanical thermal analysis (DMTA) data. The packing of molecular chain and average distance between molecular chains were analyzed by DMTA and X-ray diffraction measurements, respectively. As a result, the loss modulus, glass transition temperature ( Tg), cross-link density, average distance between molecular chains and Ea were found to be positively correlated with the degree of functionality. Meanwhile, the storage modulus of cured epoxy products at glass state was found to vary as follows: diglycidyl ether of bisphenol F (DGEBF) > tetraglycidyl diaminodiphenylmethane > triglycidyl- p-aminophenol (TGPAP). The loading of diluents decreased Tg and Ea and increased the storage modulus at glass state of DGEBF and TGPAP systems.

Fire behaviour and morphology of epoxy matrices designed for composite materials processed by infusion

The present work is about the investigation of the fire behavior of epoxy networks designed for structural composite materials used in aeronautics. Two high-Tg, infusion-suitable epoxy systems were studied. A model system was based on tetraglycidyl(diaminodiphenyl)methane (TGDDM) as an epoxy prepolymer, and 4,4′ methylene bis(2,6-diethylaniline) (MDEA) as a curing agent. A second system was based on a commercial aeronautic formulation specially designed for the infusion process. The triSilanolPhenyl POSS (POSSOH) was chosen as an additive due to the presence of phenyl groups and silanol functions that could possibly react with the network compounds. In this perspective, an aluminium salt (aluminium tri(acetylacetonate)) was introduced in presence of POSSOH in order to enhance the reaction of the additive with the epoxy monomer. The study of the morphology revealed intricate structures, with an overall good dispersion of the POSSOH in the epoxy networks. In terms of fire behaviour, same tendencies were observed for both epoxy networks, i.e. the combined presence of POSSOH and the aluminium-based additive brought significant improvements with a substantial and effective intumescent-like behaviour.

Interaction and properties of epoxy‐amine system modified with poly(phthalazinone ether nitrile ketone)

ABSTRACTAn epoxy based on the tetraglycidyl 4,4′‐diaminodiphenyl‐ methane (TGDDM)/bisphenol A type novolac(F‐51) cured with 4,4′‐diaminidiphenysulfone (DDS) has been modified with Poly (phthalazinone ether nitrile ketone)(PPENK). The interaction between the PPENK and epoxy resin have been investigated by differential scanning calorimetry (DSC), FT‐IR, and dynamic mechanical analysis (DMA). The thermal and mechanical properties were characterized by thermogravimetric analysis (TGA), thermomechanical analysis (TMA), flexural, impact strength, and the critical stress intensity factor tests. The results showed that a large number of physical crosslinks formed by intermolecular and intramolecular hydrogen bonding indeed existed in the TGDDM/F‐51/PPENK blends. These interactions gave good compatibility between PPENK and epoxy resin. So that any phase separation had not been detected by DMA and scanning electron microscope (SEM). Beyond that the interaction could also be a benefit to the thermal and mechanical properties. Compared with the neat epoxy resin, the critical stress intensity factor values reached the maximum at 10‐phr PPENK, as well as the impact strength. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42938.

An efficient healing agent for high temperature epoxy composites based upon tetra-glycidyl diamino diphenyl methane

Poly(ethylene-co-methacrylic acid) (EMAA) as a thermally activated healing agent in a high performance, high temperature tetra-glycidyl methylene dianiline (TGDDM)/diethyl toluene diamine (DETDA) mendable epoxy composite is reported for the first time. Despite curing above EMAAs melting point (Tm=85°C), healing occurred by incorporating a preliminary low temperature curing step of 5h at 80°C, prior to cure at 177°C. Healing occurred via the pressure delivery mechanism derived from tertiary amine catalysed surface condensation reactions between EMAA and hydroxyl groups from the epoxy resin. Healing efficiencies of 36%, 55% and 105% were achieved after heating at 150°C, 200°C and 230°C respectively, but decreased rapidly with continued healing. Healing at 150°C and 200°C revealed significant healing despite remaining in the glassy state. In addition, EMAA enhanced mode I interlaminar fracture toughness by more than 270% for both the DETDA and 4,4-DDS networks.

Synthesis and curing behavior of novel multifunctional hybrid oligomers

ABSTRACTNovel multifunctional hybrid vinylized epoxide oligomers (MVEOs) containing two different reactive groups were synthesized through the esterification of tetraglycidyl 4,4′‐diaminodiphenylmethane (TGDDM) with acrylic acid (AA) at various molar ratios. The changes of vinyl ester and epoxy groups in MVEOs were studied by Fourier Transform Infrared Spectroscopy, Nuclear Magnetic Resonance, and Gel permeation chromatograph. It was found that more amount of AA in the reactant would increase the contents of vinyl ester and molecular weight. The curing behavior of MVEOs has been studied by scanning differential scanning calorimetry (DSC). Two distinct exothermic peaks were observed in the MVEOs which can be attributed to the radical polymerization of vinyl ester/styrene and condensation polymerization of epoxy/MeTHPA, respectively. Two different kinds of curing programs have influenced each other which makes the exothermic peaks overlapped. The DSC scan of MVEO‐2 indicated that the radical initiated curing reaction of vinyl ester won't notably affect the curing of epoxy without MeTHPA. However, the thermal curing of vinyl ester in MVEO‐2 without MEKP/Co would be occurred with the temperature rising. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42276.

Cure behaviors and thermal stabilities of tetrafunctional epoxy resin toughened by polyamideimide

The effect of polyamideimide (PAI) content on the cure behaviors and thermal stabilities of 4,4′-tetraglycidyl diaminodiphenyl methane (TGDDM) epoxy resin/polyamideimide (PAI) blends was investigated. The experimental results revealed that the main exothermic peak and cure activation energy (E a ) of the blends decreased with increasing PAI content, presumably because the curing reaction was accelerated by the presence of secondary amine groups of the PAI backbone. The decomposition activation energy (E d ) of the blends was maximized at 5 phr PAI and decreased above this content; this was attributed to the short-chain structural network in TGDDM/PAI blends, which was derived from etherification and chain-scission reactions caused by the secondary amine of PAI.

Preparation of emulsion‐type thermotolerant sizing agent for carbon fiber and the interfacial properties of carbon fiber/epoxy resin composite

ABSTRACTA modified resin was synthesized through the reaction between dodecylamine and tetraglycidyldiaminodiphenylmethane (TGDDM), which was used as the film former of sizing agent for carbon fiber (CF). The sizing agents were prepared through phase inversion emulsification method. Fourier transform infrared spectroscopy (FTIR) was utilized to analyze the modified resin. Particle sizes of the sizing agents were tested to evaluate their stabilities. Differential scanning calorimetry (DSC) results demonstrated that the glass transition temperature (Tg) of the modified TGDDM is much higher than the Tg of the cured epoxy resin E‐44. The influences of the sizing treatment on CF were investigated by abrasion resistance, fluffs, and stiffness tests. The maximum abrasion resistance increased by 172.8%, compared with the abrasion resistance of the desized CF. Interlaminar shear strength (ILSS) results of the CF/TGDDM composites indicated that the interfacial adhesion between CF and matrix resin was greatly improved after CF was sized. The maximum ILSS value could obtain a 29.16% improvement, compared with the ILSS of the desized CF composite. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41882.

Continuous reactor preparation of thermoplastic modified epoxy‐amine prepolymers

AbstractThis paper describes a new continuous reactor method to prepare thermoplastic modified epoxy prepolymers for aerospace prepregs with the aim of replacing traditional batch reactors. Compared with batch reactors, the continuous reactor is capable of producing epoxy prepolymers through simultaneous dissolution of polyethersulfone (PES) and 4,4′‐diaminodiphenylsulfone in tetraglycidyl‐4,4′‐ diaminodiphenylmethane (TGDDM). In addition, concurrent chain extension reactions advance prepolymer molecular weights to desired viscosities in less than 2 min of mean residence time. Optical micrographs were used to define how process temperature influences PES dissolution in TGDDM in a continuous reactor. Kinetic studies confirmed that the chain extension reaction in a continuous reactor is similar to that in a batch reactor, and the molecular weights and viscosities of prepolymers were readily controlled through reaction kinetics. Atomic force microscopy was used to confirm similar cured network morphologies for formulations prepared from batch and continuous reactors. Additionally tensile strength, tensile modulus and fracture toughness analyses concluded that mechanical properties of cured epoxy matrices produced from the two reactors were equivalent. © 2014 Society of Chemical Industry

Reactive Modification of Poly(ethylene terephthalate) and its Foaming Behavior

A methodology for the preparation of chain extended poly (ethylene terephthalate) (PET) and its foams by autoclave batching foaming method was proposed. First, PET was mixed with tetraglycidyl diamino diphenyl methane (TGDDM) as chain extender to generate the branching/crosslinking molecular structure and improve the viscoelasticity of PET. Then, PET foams were prepared using supercritical CO2 as physical blowing agent. The molecular structures of various PET samples were characterized by the nuclear magnetic resonance, gelation degree and crosslinking density test. The results showed that with the introduction of TGDDM, the branching/crosslinking structure of PET appeared. The influences of various molecular structures on the thermal property and rheology of PET were also studied. The results showed that the crystallization temperature, crystallization rate, and crystallinity of various PET samples decreased with the content of TGDDM, but the modified PET had higher melt elasticity than that of pure PET. PET foam with the addition of 0.4% TGDDM had finer cellular morphology and the highest expansion ratio.

Synthesis, characterization, and properties of low viscosity tetra‐functional epoxy resin N,N,N′,N′‐ tetraglycidyl‐3,3′‐diethyl‐4,4′‐diaminodiphenylmethane

ABSTRACTTetra‐functional epoxy resin N,N,N′,N′‐tetraglycidyl‐3,3′‐diethyl‐4,4′‐diaminodiphenylmethane (TGDEDDM) was synthesized and characterized. The viscosity of TGDEDDM at 25°C was 7.2 Pa·s, much lower than that of N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM). DSC analysis revealed that the reactivity of TGDEDDM with curing agent 4,4′‐diamino diphenylsulfone (DDS) was significantly lower than that of TGDDM. Owing to its lower viscosity and reactivity, TGDEDDM/DDS exhibited a much wider processing temperature window compared to TGDDM/DDS. Trifluoroborane ethylamine complex (BF3‐MEA) was used to promote the curing of TGDEDDM/DDS to achieve a full cure, and the thermal and mechanical properties of the cured TGDEDDM were investigated and compared with those of the cured TGDDM. It transpired that, due to the introduction of ethyl groups, the heat resistance and flexural strength were reduced, while the modulus was enhanced. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40009.

Chemical degradation of TGDDM/DDS epoxy resin in supercritical 1-propanol: Promotion effect of hydrogenation on thermolysis

Abstract Chemical decomposition of an epoxy system made of tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM) and 4,4′-diaminodiphenylsulfone (DDS) in supercritical 1-propanol was investigated under different reaction temperature and time. The GC–MS results suggested that the epoxy system was decomposed to the products including aniline, N-propylbenzenamine, and 4,4′-diaminodiphenylsulfone. The change of the products' yield with time was measured by GC. In addition, the formed chars were characterized by SEM, elemental analysis, Raman and XRD. The results implied the presence of some graphite microcrystals and disordered structure in the solid residue. Upon the addition of KOH, the Guerbet reaction of 1-propanol was promoted to generate more hydrogen. A possible free-radical reaction mechanism was proposed for the depolymerization of TGDDM/DDS epoxy resin. Hydrogenation of radicals had a promotion effect on thermolysis of TGDDM/DDS epoxy resin.

Curing behavior and thermal properties of TGDDM copolymerized with a new pyridine-containing diamine and with DDM or DDS

A new pyridine-containing diamine, 4,4′-(pyridine-2,6-diylbis(oxy)) dianiline (PDD) was used as curing agent for a tetra-epoxy resin, N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM). The chemical reactivity of the diamine was evaluated using Friedman's method, and compared with traditional diamine curing agents, 4,4′-diaminodiphenylmethane (DDM) and diaminodiphenylsulphone (DDS). PDD was found to be more reactive with the epoxy groups of TGDDM than DDS but less reactive than DDM. The dynamic mechanical thermal analysis showed all materials had Tgs above 250°C and thermosets formed from TGDDM with blends of PDD with either DDM or DDS had Tgs which increased linearly with composition. Thermogravimetric analysis (TGA) of TGDDM/PDD under argon atmosphere gave a distinctive two-stage decomposition curve compared with the approximately single step observed when TGDDM was cured by the traditional amines. When carried out under air atmosphere, the TGA mass loss occurred in multiple stages and the rate of degradation for the PDD-cured TGDDM was slower than that for DDM- and DDS-cured epoxy resin. This suggests PDD enhances the flame retardancy of the cured thermosets when compared to the more traditional diamine curing systems.

Effect of epoxy resin properties on the mechanical properties of carbon fiber/epoxy resin composites

Abstract Three kinds of epoxy resins, i.e. tetraglycidyl diaminodiphenyl methane (AG80), difunctional diglycidyl ether of bisphenol-A (E51) and novolac type epoxy resin (F46) were selected as matrices for carbon fiber/epoxy composites. The objective of this work is to study the mechanical properties of fiber/epoxy composites by using these three kinds of epoxy resins with different physical and chemical performance. The results show that the composites fabricated with AG80 present the best stiffness and the composites prepared with E51 have the best toughness. The stiffness and toughness of the composites prepared with F46 are middle values located between those for AG80/epoxy and E51/epoxy composites. Thus, the mixed epoxy resin is a promising approach for industrial production.

Evaluation of the chemical interaction between carbon nanotubes functionalized with TGDDM tetrafunctional resin and hardener DDS

In this work, the chemical interaction between carbon nanotubes (MWCNT) functionalized with acyl chloride (SOCl2) and polymer chain tetrafuncional N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) and hardener 4,4′diaminodiphenyl sulfone (DDS) has been monitored by Fourier transform infrared spectroscopy (FTIR) with a attenuated total reflectance (ATR) coupled. MWCNT were obtained from the pyrolysis of a mixture of camphor and ferrocene into a oven. The functionalization process was done by oxidative treatment in order to incorporate carboxylic group over the walls of MWCNT, before to be used SOCl2. The functionalized carbon nanotubes were evaluated by X-ray photoelectron spectroscopy (XPS), Raman and transmission electron microscopy (TEM). Nanostructured composites were processed by using epoxy resin with MWCNT in varying percentages. In this work it was observed that different percentages of functionalized nanotubes modify the interaction between the composite matrix and curing agent, where can be observed that in specimens with content less than 1wt% MWCNT the chemical bond occurs preferentially from the opening of the SO double bond of the hardener and when is used MWCNT content higher than 1wt% there is little chemical interaction with the SO bond of the hardener and most MWCNT binds to amine.

Thermal, electrical and morphological properties of DGEBA/DDM and TGDDM/DDM epoxies modified by a flexible diepoxide and octaphenylamine-POSS

Polyhedral oligomeric silsesquioxane (POSS) nanocrosslinker namely octaaminophenyl silsesquioxane reinforced with 1,1-bis(3-methyl-4-glycidyloxyphenyl)cyclohexane (diepoxide) modified diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamino diphenyl methane (TGDDM) epoxy resins and cured with 4,4′-diaminodiphenylmethane (DDM). The chemical reactions that occurred between epoxy resins and DDM with POSS were confirmed by Fourier transform infrared spectroscopy. POSS-reinforced hybrid diepoxide-epoxy resin nanocomposites were characterised for their thermal, electrical and morphological properties. Tg and heat distortion temperature of hybrid epoxy increases with increased incorporation of POSS. The data obtained from thermal studies indicated that the incorporation of nano-POSS into diepoxide-modified hybrid systems possess improved thermal stability. Dielectric properties decreased with increasing percentage of POSS in both systems. The nanolevel dispersion of octaaminophenyl silsesquioxane (POSS) was confirmed by X-ray diffraction analysis and transmission electron microscope studies.

Studies on synthesis and characterization of hydroxyl-terminated polydimethylsiloxane-modified epoxy bismaleimide matrices

This work reports the development of hydroxyl-terminated polydimethylsiloxane (HTPDMS)-toughened tetraglycidyl diaminodiphenyl methane (TGDDM) epoxy matrix systems. The siliconized epoxy systems were further modified with various percentages of (5, 10 and 15 wt%) 10-phenyl-phenonoxaphosphine-3,8-di(2-hydroxy-3-( p-male-imidobenzoyloxy)propyl) ester-10-oxide (EPBMI) and cured by diaminodiphenyl sulfone. Thermal, mechanical and morphological properties of the prepared samples were studied by standard methods. In comparison with the unmodified epoxy resin, HTPDMS-incorporated TGDDM resin showed increased impact strength with a reduction in tensile strength, flexural strength and glass transition temperature ( Tg). But in the case of bismaleimide (BMI; EPBMI)-incorporated epoxy resin, tensile strength, flexural strength and Tg showed an increasing trend. However, the introduction of both siloxane and BMI into epoxy influences the mechanical and thermal properties according to their percentage content. The morphology of the silconized and the BMI-modified epoxy systems was also studied by scanning electron microscopy.

Preparation and Characterization of Cyclohexyl Moiety Toughened POSS-Reinforced Epoxy Nanocomposites

Polyhedral oligomeric silsesquioxane (POSS)-reinforced epoxy nanocomposites were prepared by reacting commercially available diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamino diphenyl methane (TGDDM) epoxy resins with 1,1-bis(3-methyl-4-glycidyloxyphenyl)cyclohexane (Cy-Ep) separately and reinforced with POSS nanocluster. POSS (OAPS)-reinforced hybrid Cy-Ep-epoxy resin castings were characterized for their mechanical and morphological properties. The data obtained from mechanical studies indicated that the incorporation of nano OAPS into Cy-Ep modified hybrid systems results in improved stability. Among the epoxy systems studied, the TGDDM-based hybrid epoxy system exhibited higher values of tensile and flexural properties than that of the DGEBA hybrid epoxy system, whereas the impact strength of the DGEBA system was higher than that of the TGDDM system. The dispersion of POSS was confirmed by scanning electron microscopy and visual observation studies.

An investigation of cure and thermal stability of poly(amide‐amidic acid) modified tetraglycidyl 4,4′‐diaminodiphenylmethane/4,4′‐diaminodiphenylsulfone

AbstractIn this work, poly(amide‐amidic acid) (PAA) was used to modify tetraglycidyl 4,4′‐diaminodiphenylmethane (TGDDM)/4,4′‐diaminodiphenylsulfone (DDS) system. Results of non‐isothermal differential scanning calorimetry analysis indicated that PAA played a role of catalyst during the process of the curing reaction. The curing mechanism was studied by Fourier transform infrared spectroscopy, showing that the PAA acted as a co‐curing agent in the system. The glass transition temperature decreased firstly and then increased with the increase of the PAA content. PAA equally rendered TGDDM more fire resistant with higher char yield. On examining the fracture surface morphology using scanning electron microscopy, it was observed that there was no obvious phase separation when the content of PAA was less than 20 phr (per hundred weight of TGDDM/DDS resin), however, phase separation was observed when the content of PAA was 25 and 30 phr. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013