Methyltetrahydrophthalic Anhydride Research Articles

Curing and degradation kinetics of crosslinked epoxidized soybean oil with isosorbide-based curing agent

This work explores the synthesis of the isosorbide-based curing agent with methyltetrahydrophthalic anhydride (MTHPA). Synthesized for the first time, the isosorbide methylphthalate acid (IMPA) and its effects on the crosslinking of epoxidized soybean oil (ESO) are investigated. The curing and degradation kinetics of the synthesized compounds were investigated for molar ratios 1:1, 1:0.50 and 1:0.25 for ESO/IMPA and 1:1 ESO/MTHPA. ESO/IMPA 1:0.50 had the lowest cure activation energies during the highest cure conversion range, between 10% and 55%, and the highest degradation activation energies during the 30 and 60% conversion. The Friedman and Vyazovkin isoconversional models provided R2 > 0.99 for cure, except for the ESO/MTHPA composition, presenting a lower R2. In degradation kinetics, the Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) kinetic models presented R2 > 0.99, while the degradation mechanisms were adequately adjusted with Avrami-Erofeev (An) and autocatalytic (n,m)th order (Cnm) during the first and second degradation step. Microstructural analyzes and deeper investigations into the degradation mechanisms in the solid state indicated that in the ESO/IMPA and ESO/MTHPA compounds the processes are controlled by diffusion.

Recyclable and shape‐memory hydantoin epoxy resins based on dynamic ester‐exchanged bonds

AbstractThe permanent crosslinked network imparts chemical and mechanical stability to crosslinked elastomers, making their recycling a serious environmental issue. The decomposition products of pentaaryl diazoxide in the structure of hydantoin epoxy resin are nitrogen and carbon dioxide, and it is an environmentally friendly resin material. Here, we demonstrate a reversible covalent bonding reaction catalyzed by Zn2+ between the ester bond formed by the hydantoin epoxy resin and the acid anhydride, and construct a reversible crosslinked network structure of the environmentally friendly acid anhydride/hydantoin epoxy resin material. The strength, hardness and toughness of the cured material are greatly improved by optimizing its ratio. The ester exchange bonding can be reversible with temperature, which leads to the shape memory capability of the synthesized cured material. The cured product of HMY1 was recovered with ethylene glycol and completely dissolved at 180°C for 11 h. Ethylene glycol was volatilized at 190°C to obtain decomposed epoxy oligomer (DEO), which was added to the HMY1 resin system (the amount of DEO was 30 wt% of the total mass of the resin), and the network structure was cross‐linked to enable it to be recovered and remanufactured. Thus, this work provides a new avenue for the environmentally friendly development of recyclable, reconfigurable, and thermally adaptable shape‐memory hydantoin epoxy materials.Highlights Hydantoin epoxy resin eventually breaks down into non‐toxic CO2 and N2. Hydantoin epoxy and methyl tetrahydrophthalic anhydride form a reversible dynamic chemical bond catalyzed by Zn2+. Ethylene glycol can recover and reuse the solidified product.

Characterization of methyltetrahydrophthalic anhydride esterified corn starch and their ability in stabilizing Pickering emulsion

Methyltetrahydrophthalic anhydride (MeTHPA) esterified corn starches (MeCS) with degrees of substitution (DS) of 0.0066–0.072 were prepared, characterized and applied to stabilize Pickering emulsion. Fourier transform infrared spectroscopy analysis revealed the presence of a new ester group in MeCS. MeTHPA modification damaged the crystal structure of the corn starch, made its surface structure rough and irregular, and increased its contact angle. These changes were positively correlated with the DS of MeCS. Compared to native corn starch, the particle size of MeCS increased first and then decreased with an increase in DS, the lowest value (4.67 ± 0.08 μm) was observed for MeCS with highest DS (0.072). The stability of Pickering emulsions stabilized by MeCS with a DS of 0.072 was better than those stabilized by MeCS with lower DS (0.0066–0.019), which may attribute to their smaller particle size and higher viscosity. MeCS (DS 0.072) as emulsifiers at a concentration of 3% (w/v) could keep the emulsion stable even after 50 days of storage. This research suggested that MeCS at proper DS and concentration levels may serve as effective particle stabilizers for Pickering emulsions.

Degradation kinetics of epoxidized soybean oil composites filled with sisal fiber

AbstractEpoxidized soybean oil (ESO) composites were cured with methyl tetrahydrophthalic anhydride (MTHPA) and 2,4,6‐tris(dimethylaminomethyl)phenol (DEH 35) as a catalyst, sisal fibers were added at 10% and 30% of percent per weight. Composites curing was monitored using Fourier transform infrared spectroscopy, whereas the thermal stability and the degradation kinetics were investigated using thermogravimetry (TG). ESO/MTHPA/DEH35/S10 and ESO/MTHPA/DEH35/S30 composites displayed curing temperatures approximately 100°C lower related to ESO/MTHPA/DEH35, as well as higher degree of conversion. Sisal addition improved the thermal stability, shifting the weight loss shifting the weight loss onset to higher temperature (from 82 to 120°C). Thermal degradation energy was determined using Friedman, Kissinger‐Akahira‐Sunose and Ozawa‐Flynn‐Wall models. Sisal significantly increased , especially in the intermediate phase (α = 0.2 and 0.8). The degradation kinetics was investigated by TG, and the degradation mechanisms modeled using Kamal‐Sourour, Sestack‐Berggren, and 1st order (F1), showed excellent fit, with R2 > 0.99. Acquired results demonstrate that sisal fiber addition benefited the curing process and increased the thermal stability of ESO composites.

Preparation of HNTs‐e‐POSS hybrid nanoparticles and modification of gallic acid epoxy resin

AbstractGallic acid is a renewable plant phenolic resource, and the polyphenolic bio‐based epoxy resin prepared from it can be used as a substitute for bisphenol A epoxy resin in certain fields. However, bio‐based epoxy resins used in the field of high‐performance composite material matrices often require modification. In this paper, firstly, γ‐(2,3‐epoxypropoxy)propyl trimethoxysilane (KH560) was used as the raw material to prepare epoxy‐based cage silsesquioxanes (E‐POSS). Then, E‐POSS was grafted onto γ‐aminopropyltriethoxysilane (KH550) modified halloysite nanotubes (m‐HNTs) to prepare a novel hybrid nanoparticle HNTs‐e‐POSS. Experimental analysis shows that ring opening reactions of amino and epoxy groups can occur between m‐HNTs and E‐POSS, forming a hybrid nanoparticle system of POSS aggregates on the surface of HNTs. Bio‐based nanocomposites were prepared by adding different mass fractions of hybrid nanoparticles HNTs‐e‐POSS into polyphenol type gallic acid epoxy resin matrix (GAER) and using methyltetrahydrophthalic anhydride as curing agent. The properties and micromorphology of the composite were analyzed and characterized. The research showed that with the addition of HNTs‐e‐POSS nanoparticles, the strength and toughness of the composite resin system show a pattern of first increasing and then decreasing, while the storage modulus(E′), glass transition temperature (Tg), and thermal stability of the composite material increased. Mechanical performance analysis shows that the introduction of 0.5 wt% HNTs‐e‐POSS would increase the tensile strength of the composite by 25.46%, while adding 0.75 wt% HNTs‐e‐POSS can increase the impact strength by 15%. The E′(30°C) increased by 24.2% and Tg increased by 7.7°C when the HNTs‐e‐POSS addition was 0.25 wt%.Highlights Prepared hybrid nanoparticle HNTs‐e‐POSS by grafting POSS onto the HNTs surface. Application of HNTs‐e‐POSS in modification of bio‐based gallic acid epoxy resin. HNTs‐e‐POSS can co‐cured with epoxy matrix to increase the crosslinking degree. The strength, toughness, and modulus of gallic acid epoxy resin are improved. Tg and thermal stability of gallic acid epoxy resin are enhanced.

Insight of charge injection barrier at the copper/epoxy resin interface with cross-linking molecules: First-principles calculation and experimental verification

Understanding charge injection at a metal/cross-linking epoxy resin (EP) interface facilitates the design and application of high-power electric and electronic devices. This paper focuses on the charge injection barrier at the metal/EP interfaces using first-principles calculation. Two fragmentary structures, obtained from cross-linking EP with amine and anhydride curing agent, were selected to construct interface models on a Cu(111) slab. The injection barrier, dipole moment, charge transfer, and vacuum energy level shift (Δ) at the interfaces were examined. The model with the anhydride groups produced higher electron and hole injection barriers than the interface model with the amine groups. The model with the amine groups had a higher Δ, which was derived from molecule dipole and charge transfer. An increase in the work function and Δ caused by an electric field caused an increase in the electron injection barrier and a decrease in the hole injection barrier. Experimental results of the methyl tetrahydrophthalic anhydride cross-linking EP showed a higher charge injection than that of m-phenylenediamine cross-linking EP, providing experimental verification of the theoretical calculation.

The synergistic impacts of hybrid nanofillers of graphene nanoplatelets/carbon nanotubes on curing behavior of an epoxy‐vinyl ester interpenetrating polymer network nanocomposite coating

AbstractThis study investigated the synergistic effects of hybrid graphene nanoplatelet (GnP)/multi walled carbon nanotube (MWCNT) nanofillers at various loadings on the kinetics of curing of the epoxy (EP)/vinyl ester (VE) interpenetrating polymer network (IPN) system, with a mass ratio of 1:1. Fourier transform infrared spectroscopy (FTIR), dynamic mechanical thermal analyzer (DMTA) and differential scanning calorimetry (DSC) were used to monitor the interpenetration process of EP and VE and likely interactions between the components of the different resin systems in IPN. The curing behavior of all prepared samples under non‐isothermal conditions was studied using DSC at four heating rates. Two different isoconversional approaches were applied to evaluate the reaction kinetics, that is, the Friedman and the advanced Vyazovkin methods. The obtained activation energy curves for all samples revealed a complex curing behavior involving three stages; early IPN stage, IPN growth stage, and late IPN stage. Then, the activation energy values for each reaction step were determined based on the Friedman method. The presence of GnP/MWCNT nanoparticles showed no catalytic effect on the reaction of VE with methyl ethyl ketone peroxide (MEKP). In contrast, incorporating GnP/MWCNT nanoparticles significantly decreases the activation energy values of the reaction of ring opening of epoxides with methyl tetrahydrophthalic anhydride (MTHPA) 1‐methyl imidazole (‐Mi) and the reaction of esterification of the hydroxyl groups of VE with MTHPA.Highlights Model‐free methods used to curing study of epoxy‐vinyl ester IPN nanocomposites FTIR, DSC and DMTA used for evaluation IPN formation of EP/VE It showed that the improvement of dispersion and compatibility by using of GnP/MWCNT hybrid Frideman and Vyazovkin methods used to calculate Ea of nanocomposites DSC thermograms were deconvoluted into three individual peaks.

Degradation kinetics of epoxidized soybean oil

AbstractThis work deals with the degradation kinetics of epoxidized soybean oil, whereas the weight loss of epoxidized soybean oil (ESO) cured with methyl tetrahydrophthalic anhydride (MTHPA) as hardener and 2,4,6‐tris (dimethylaminomethyl) phenol (DEH 35) as catalyst displayed two main regions in the thermogravimetry (TG) plots. Nevertheless, deconvolution of the weight loss plots presented three or more events depending on the composition and experimental parameters. Increase the MTHPA addition led to a decrease in the activation energy (AE) for curing which conducted to an increased AE during the degradation. Friedman's isoconversional model exhibits proper R2 for the curing kinetics, but lower R2 values for lower anhydride contents during the degradation kinetics analyses. Kissinger‐Akahira‐Sunose (KAS) and Ozawa‐Flynn‐Wall (OFW) models displayed the best R2 during the kinetics evaluation, whereas the degradation mechanisms fitted reasonably with Avrami‐Erofeev (An) and nth‐order autocatalytic (Cn) during the first and second weight loss regions. Microstructural analyzes and in‐depth investigations into the thermal degradation mechanism of ESO suggest two possible pathways, that is, production of carbonic groups through heterolytic scission, and formation of electrically stable groups with saturated carbon bonds.

Anhydride-cured epoxidized dehydrated castor oil (EDCO) containing organically modified zinc oxide (ZnO) nanoparticles

The incorporation of nanoparticles in various coatings has enhanced coating performances, thus attracting many researchers to explore nanocomposite coatings. In order to synthesize a novel nanocomposite coating, dehydrated castor oil (DCO - biobased non-edible vegetable oil) was epoxidized with performic acid (HCOOOH) and cured with methyltetrahydrophthalic anhydride (MTHPA) in presence of tertiary amine accelerator, 1-methyl imidazole (1-MI) and characterized by FTIR and 1H NMR. Simultaneously, zinc oxide (ZnO) nanoparticles were synthesized by mixing zinc acetate dihydrate (ZnAc2) with oxalic acid dihydrate (Ox2) by precipitation method and then modified organically with (3-glycidyloxypropyl) trimethoxysilane (GPTMS) by sol–gel method which was confirmed by DLS, FTIR, XRD, E-SEM, EDAX, TEM and XPS. These GPTMS-modified ZnO (G-ZnO) nanoparticles were incorporated into EDCO in various concentrations (0–3 wt%) and their mechanical, chemical, thermal and anticorrosion performances were evaluated. All the coatings demonstrated outstanding mechanical and chemical properties (except for alkali resistance) whereas thermal resistance and anticorrosion properties were enhanced with increase in the loading of G-ZnO nanoparticles.

Computationally driven design of low dielectric-loss epoxy resin for medium-frequency transformers

The design of low dielectric-loss epoxy resin (EP) systems plays an important role in the insulation optimization of medium-frequency transformers (MFTs). Due to the diversity of EP and curing agents, the traditional design method inspired by dielectric-loss measurements cannot complete low dielectric-loss EP systems design in plentiful candidate EP systems. In this study, molecular dynamics (MD) computation was introduced to drive the design of a low dielectric-loss EP system for MFTs. By analyzing the relationship between the dielectric loss and molecular motion of the EP systems, two MD results were selected as descriptors to indicate the dielectric loss of EP systems, including mean square displacement and α-transition temperature. Eventually, the low dielectric-loss EP system blending EP, methyl tetrahydrophthalic anhydride, and dodecenyl succinic anhydride was effectively designed according to the descriptors. The rationality of the computationally driven design was verified by broadband dielectric spectroscopy measurement and the finite element method. Compared with previous EP systems, MFT insulated with the designed EP system had not only a 40% lower dielectric loss (9.79 W) but a higher overload capacity. This study provides an effective method for the design of low dielectric-loss EP systems.

Cross-link Degree Dependence of Electronic, Water Uptakes and Thermal-mechanical Properties of Epoxy Resin Polymers: Molecular Simulations

Epoxy resin (EP) is a widely used polymer matrix. A deep understanding of the structure/property relationship of EP at the molecular level is critical to realizing the materials’ full potential. Here, molecular simulations are used to calculate and compare the electronic, water uptakes and thermal-mechanical properties of EP dependent on different cross-link degrees, bisphenol A diglygde ether (DGEBA) cross-linked with methyl-tetrahydro phthalic anhydride (MTHPA), revealing these inter-relationships. The results show that they have the same energetic spectrum character of electronic states, which is determined by compositions and bonding configurations of chemical groups in EP polymers, only with the different magnitudes of the density of states which are proportional to the number of cross-link points or curing agents and monomers. Furthermore, the van der Waals forces, not the cross-link chemical bonds, dominate the molecular chain interactions and motions in EP polymers below the glass transition temperature, while cross-link structure determines the configuration of the aggregated molecular chains and thermal properties of EP polymers above the glass transition temperature. Meanwhile, the hydrostatic mechanical modulus of EP material is primarily derived from cross-link structure even below the glass transition temperature. These results lay the foundation for designing and manufacturing customized EP with desirable electric and thermal-mechanical properties.

Molecular dynamics simulation of crosslinking process and mechanical properties of epoxy under the accelerator

AbstractTo simulate the crosslinking process of epoxy resin under the accelerator action, the crosslinking system of bisphenol‐A diglycidyl ether (DGEBA) as a monomer, methyl tetrahydro‐phthalic anhydride (MTHPA) as a thermal curing agent and 2,4,6‐tris (dimethylaminomethyl) phenol (DMP‐30) as a thermal curing accelerator has been studied using molecular dynamics (MD) simulation. An algorithm that can construct the high‐crosslinked system with different crosslinking density is completed based on the Perl language, and the subsequent properties are simulated. The results of molecular dynamics simulation show that modulus have an increasing trend, and glass transition temperature (Tg) raises from 325 K to 480 K when crosslinking density is from 0% to 95.5%. Conversely, cohesive energy density lessens from 620 J/cm3 to 170 J/cm3, solubility and Poisson's ratio decrease, and the tensile strength firstly increases and then diminishes. The friction coefficient decreases firstly and then increases, meanwhile, the temperature suddenly adds by 20 K and the relative concentration distribution (RCD) grows by 1.58 times at the contact surface. This study predicts for the crosslinking process and micro mechanical properties in the DGEBA/MTHPA/DMP‐30 system.

Effect of hardener and catalyst contents on curing and degradation of epoxidized soybean oil

AbstractEpoxidized soybean oil (ESO) compounds were cured with methyl tetrahydrophthalic anhydride (MTHPA) as hardener and 2,4,6‐tris (dimethylaminomethyl) phenol (DEH 35) as catalyst. To figure out MTHPA and DEH 35's influence during curing and degradation, ESO/MTHPA/DEH 35 compounds were investigated using Fourier‐Transform Infrared Spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetry (TG). FTIR spectra of uncured resin showed the secondary interactions among ESO's carbonyl groups with MTHPA and DEH 35's hydroxyls and amines. Curing progress was followed tracking the evolution of reactive groups, that is, epoxy and carbonyl bands and corroborated with released heat of DSC scans. ESO 87:5 and ESO 87:10 compounds cured using higher heating rates presented higher released enthalpy suggesting denser reticulation, and they also displayed lower activation energy for curing, which was evaluated using the Friedman model. Increasing the hardener and catalysts contents promoted higher thermal stability and lower degradation rates, while higher for degradation was verified.

An Itaconic Acid‐Based Phosphorus‐Containing Oligomer Endowing Epoxy Resins with Good Flame Retardancy and Toughness

AbstractWith the aim to reduce the influence of flammability and brittleness of epoxy resin (EP) on its applications, a phosphorus‐containing oligomer (BID) containing phosphophenanthrene group and flexible chain segment is designed and applied to methyltetrahydrophthalic anhydride (MeTHPA) curing EP systems. Compared with EP/MeTHPA, the glass transition temperature (Tg) declines after introducing BID. But the addition of BID endows EP/MeTHPA with good flame retardancy. When the dosage is only 19.2 wt.%, the limiting oxygen index (LOI) of EP/BID/MeTHPA increases by 77% to 36% (P content: 1.5 wt.%) compared with EP and reaches the vertical combustion (UL‐94) V‐0 rating. Cone calorimetry (CC) results reveal that PHRR and THR drop by 40% and 31%. The pyrolytic process and char residue data analysis show that BID plays flame‐retardant role in gas phase and condensed phase. In addition, impact and flexural and tensile strength improve by 84%, 19% and 54% individually, proving that BID holds a potential on enhancing mechanical performance of EP/MeTHPA.

Enhancement of surface electrical performances of epoxy film by blending with fluorinated and crosslinking monomer

• Fluorinated monomers were synthesized through a facile method to prepare fluorinated epoxy films. • Effects of introducing –CF 3 groups on physicochemical characters of the films are studied. • Electrical strength of the fluorinated film was evidently enhanced. In order to introduce fluorine-containing functional groups into epoxy resins to stably enhance the surface electrical properties of thin films, the trifluoromethyl group containing diglycidyl ethers bisphenol A (F-DGEBA) monomer was prepared by a simple and environmentally friendly method. Further, the film was obtained by blending the prepared monomers with DGEBA in different proportions and curing at high temperature with methyl tetrahydrophthalic anhydride (MTHPA). The prepared films not only have improved hydrophobic properties, but also exhibit better surface electrical properties. With the increase of the content of F-DGEBA, the epoxy resin films have higher surface insulation strength and better potential decay performance, which is due to the existence of –CF 3 groups changing the distribution of deep and shallow traps. Compared with the non-fluorinated film, the flashover voltage of the fluorinated film with the best electrical properties is increased by 32.2%, and the potential decay rate is also much faster.

Preparation of HNTs‐d‐GO hybrid nanoparticles for gallic acid epoxy composites with improved thermal and mechanical properties

AbstractKH550 modified halloysite nanotubes (m‐HNTs) were hybridized with sulfoxide chloride acylated graphene oxide (m‐GO) to prepare hybrid nanoparticles (HNTs‐d‐GO). The microstructure and morphology analysis of HNTs‐d‐GO hybrid nanoparticles showed that the ordered lamellar structure of GO after acyl chlorination was stripped, and the organic groups on the surface of the lamellar increased. HNTs‐d‐GO hybrid nanoparticles were formed through the amidation of m‐HNTs and m‐GO. Then HNTs‐d‐GO hybrid nanoparticles were incorporated in galic acid epoxy resin to improve the thermal and mechanical properties. HNTs‐d‐GO/galic acid epoxy resin (HNTs‐d‐GO/GAER) bio‐based nanocomposites were prepared with methyl tetrahydrophthalic anhydride as curing agent. The galic acid epoxy composites with the addition of HNTs‐d‐GO exhibited significant enhancements of impact strength, tensile strength, storage modulus, and glass transition temperature. The initial thermal decomposition temperature (T5%) decreased, and the mass retention at 800°C increased, thermal stability of HNTs‐d‐GO/GAER composites were enhanced. At an optimum concentration of 0.75 wt% HNTs‐d‐GO, a simultaneous increase in strength and toughness was observed in comparison to the unfilled cured resin, the impact strength is 2.87 kJ/m2, which is 30.4% higher than pure GAER, and the tensile strength is 42.62 MPa, which is 29.2% higher than pure GAER. Compared with pure gallic acid epoxy resin, the content of HNTs‐d‐GO is 0.25 wt%, Tg increased by 28.9°C.

Impact of magnetic ionic liquids as catalystson the curing process of epoxy/anhydride system: Mechanistic investigation and dynamic‐mechanical analysis

AbstractCyclic acid anhydride – based hardeners provide excellent physic‐mechanical and thermal properties to epoxy networks. However, the curing process takes place at relatively high temperature, thus limiting the applications as coatings and free‐heating devices. The present work describes for the first time the efficient catalytic action of imidazolium‐ and phosphonium‐ based ionic liquids (IL) bearing iron tetrachloride (FeCl4) as counteranion for the curing process of epoxy prepolymer (EP)/methyl tetrahydrophthalic anhydride (MTHPA) even at room temperature. Indeed, both differential scanning calorimetry and rheological analysis revealed that the addition of 5 phr of trihexyl (tetradecyl)‐phosphonium iron tetrachloride (P66614. FeCl4) resulted in faster curing process when compared with systems cured with conventional tertiary amine. The gelation at room temperature occurred before 24 h with this magnetic IL. Moreover, the systems catalyzed by P66614. FeCl4 presented higher glass transition temperature, higher storage modulus and higher crosslink density as indicated by dynamic‐mechanical analysis (DMA). A mechanism for the curing process was proposed based on DSC and Fourier transform infrared analysis. These results highlight the importance of magnetic ILs as catalysts for the curing process of EP/MTHPA system and open new avenues for applications of this system as a room temperature‐based curing system.

Comparison of the performances of epoxy resin thermosets cured by two P-containing anhydrides

Two P-containing anhydrides, ethyl (2,5-dioxotetrahydrofuran-3-yl) (methyl) phosphinate (MTA-MA) and 3-(5-oxido-6H-phosphanthridin-5-yl) dihydrofuran-2,5‑dione (DOPO-MA), were synthesized and used along with methyl tetrahydrophthalic anhydride as co-curing agents for curing epoxy resin (EP, mark E51). Via the cross-linking reaction during the solidifying process, P element was introduced into EP matrix via coherent bond. The results showed that both flame-retarding curing agents improved the flame retardancy of EP and MTA-MA exhibited a better performance than DOPO-MA. When the P content in the EP matrix reached 1.0 wt%, the EP/MTA-MA-1.0 thermoset passed UL-94 V0 rating and the limiting oxygen index (LOI) was 32.6%. In addition, EP/DOPO-MA-1.0 achieved UL-94 V1 rating and the LOI value was 30.2%. Cone calorimeter tests, scanning electron microscopy-energy dispersive x-ray spectroscopy, and pyrolysis gas/mass spectrometry results indicated that EP/MTA-MA exhibited better flame-retardancy performance in both the gas and condense phases. In addition, the thermal stability, mechanical properties, and glass transition temperature of EP/MTA-MA and EP/DOPO-MA were studied.

Hydrogenation of MTHPA to MHHPA over Ni-based catalysts: Al2O3 coating, Ru incorporation and kinetics.

Because of its excellent performance, methyl hexahydrophthalic anhydride (MHHPA) is a new anhydride-based epoxy resin curing agent after methyl tetrahydrophthalic anhydride (MTHPA). To improve the activity and stability of conventional RANEY® nickel catalysts in the catalytic hydrogenation of MTHPA to MHHPA reaction, RANEY® nickel encapsulated with porous Al2O3 and alumina-supported Ni-Ru bimetallic catalysts were designed and synthesized in this study. The physicochemical properties and surface reactions over the catalysts were characterized by N2 adsorption and desorption, X-ray diffraction (XRD), hydrogen temperature-programmed reduction/desorption (H2-TPR/TPD), X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and in situ diffuse reflectance infrared Fourier transformations spectroscopy (DRIFTS). The kinetic model of MTHPA hydrogenation over NiRu/Al was established and the parameters were estimated using the least-square method. The results showed that the encapsulation of porous Al2O3 on the surface of RANEY® nickel enhanced the stability of the Ni skeleton and the adsorption ability of the reactant molecules, which improved its activity for the hydrogenation reaction. The introduction of Ru improved the dispersion and stability of metallic Ni, which greatly increased the conversion ability towards MTHPA hydrogenation, but it had a trend to cause C[double bond, length as m-dash]C bond transfer at lower temperatures, increasing the hydrogenation difficulties. The kinetic results based on Ni-Ru bimetallic catalyst showed that the MTHPA hydrogenation reaction rate was first-order with respect to MTHPA concentration and 0.5-order with respect to hydrogen partial pressure, and the apparent activation energy of the hydrogenation reaction was 37.02 ± 2.62 kJ mol-1.

Performance optimization of shape memory epoxy polymers based on machine learning

AbstractIn this study, we proposed a machine learning (ML) method to optimize the comprehensive performance of shape memory epoxy polymers (SMEPs) based on experimental data as samples. Firstly, a series of SMEPs specimens were prepared, and their properties were evaluated respectively by testing four indexes including the glass transition temperature (Tg), bending strength, strain fixation rate (Rf), and strain recovery rate (Rr). Subsequently, ML used these experimental data as samples for feature learning to investigate the influence of each component on these properties. The results indicated that methyltetrahydrophthalic anhydride was more favorable toTgand bending strength than methylhexahydrophthalic anhydride (MHHPA) as a curing agent. However, a certain amount of MHHPA must be included in the system to guarantee a higherRfandRr. Moreover, the right amount of bisphenol A cyanate ester in the system improved the comprehensive properties of SMEPs, especially the shape memory effect. Finally, a SMEPs system with superior properties was acquired through the optimization of four indexes ofTg, bending strength,RfandRr. Therefore, this study shows that ML methods can also be used to investigate SMEPs that require more specific excellent performance.