Kinetic Study Of Reaction Research Articles

Polyurethanes and Polyallophanates via Sequence-Selective Copolymerization of Epoxides and Isocyanates.

Aryl isocyanates are introduced as comonomers for ring-opening copolymerization (ROCOP) with epoxides. Informed by studies of reaction kinetics, we show that divergent sequence selectivity for AB- and ABB-type copolymers can be achieved with a single dimagnesium catalyst. The resulting materials respectively constitute a new class of polyurethanes (PUs) and a new class of materials featuring an unprecedented backbone structure, the polyallophanates (PAs). The successful use of isocyanate comonomers in this way marks a new direction for the field of ROCOP while providing distinct opportunities for expansion of PU structural diversity. Specifically, the methodology reported herein delivers PUs featuring fully substituted (tertiary) carbamyl nitrogen atoms, a structural motif that is almost inaccessible via extant polymerization strategies. Thus, in one step from commercially available comonomers, our methodology expands the scope of ROCOP and gives access to diverse materials featuring both privileged (PU) and unexplored (PA) microstructures.

Interfacial Reactions between Ga and Cu-10Ni Substrate at Low Temperature.

Ga alloys have been attracting significant renewed attention for low-temperature bonding applications in electronic packaging. This study systematically investigates the interfacial reaction between liquid Ga and Cu-10Ni substrates at 30 °C. In addition to CuGa2 formed from binary Ga/Cu couples, a layer of nanocrystalline Ga5Ni and CuGa2 formed between the Cu-10Ni substrate and the blocklike micrometer scale CuGa2 layer. The growth of interfacial intermetallics (IMCs) on the Cu-10Ni substrate was substantially accelerated compared to the IMC growth in binary Ga/Cu couples. Reaction kinetics study shows the IMC growth from the Cu-10Ni substrate was controlled by reaction and volume diffusion, while the IMC growth from the Cu substrate was controlled by volume diffusion. It is also found that the presence of Ni within the CuGa2 phase resulted in improved thermal stability and a smaller coefficient of thermal expansion during heating from 25 to 300 °C, using synchrotron XRD analysis. There was least thermal expansion anisotropy among most of the IMCs that form in conventional Sn-based solder alloys, including Cu6Sn5 and so forth. It is concluded that using a Cu-10Ni substrate as opposed to a Cu substrate could achieve sufficient metallurgical bonding within shorter processing time. The results have implications for broadening the application temperatures when using Ga as a low-temperature joining material.

Optimization, kinetic and thermodynamic studies on sustainable biodiesel production from waste cooking oil: An Indian perspective

In India, the biodiesel industry is promising and growing at a rapid rate. Several attempts have been made using non edible feedstock to develop the commercial and sustainable biodiesel industry. In this perspective, this study has aimed to optimize four main factors; catalyst quantity, methanol: waste cooking oil molar ratio, mixing intensity and reaction time, which would influence the conversion of waste cooking oil to biodiesel. Response surface methodology integrated with desirability function approach was used to determine the best operative conditions. The optimal reaction parameters for maximum biodiesel yield (90 ± 0.25%) were identified as 0.6%w/w catalyst loading, 10.6:1 methanol to waste cooking ratio, 559 rpm mixing intensity and 63 min reaction time. The study of reaction kinetics revealed that the experimental data followed the first order reaction kinetics and the energy required to activate the molecules to undergo chemical transformation was calculated as 57.82 kJ/mol. The important thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), and the Gibbs free energy (ΔG) were estimated to assess the characteristics of the transesterification process. The values of the thermodynamic parameters were found to be ΔH = 55.09 kJ/mol, ΔS = −0.103 kJ/mol K and ΔG = 89.90 kJ/mol, respectively.

Catalytic Effect of Hydrogen Bond on Oxhydryl Dehydrogenation in Methanol Steam Reforming on Ni(111).

Dehydrogenation of H3COH and H2O are key steps of methanol steam reforming on transition metal surfaces. Oxhydryl dehydrogenation reactions of HxCOH (x = 0–3) and OH on Ni (111) were investigated by DFT calculations with the OptB88-vdW functional. The transition states were searched by the climbing image nudged elastic band method and the dimer method. The activation energies for the dehydrogenation of individual HxCOH* are 68 to 91 kJ/mol, and reduced to 12–17 kJ/mol by neighboring OH*. Bader charge analysis showed the catalysis role of OH* can be attributed to the effect of hydrogen bond (H-bond) in maintaining the charge of oxhydryl H in the reaction path. The mechanism of H-bond catalysis was further demonstrated by the study of OH* and N* assisted dehydrogenation of OH*. Due to the universality of H-bond, the H-bond catalysis shown here, is of broad implication for studies of reaction kinetics.

Kinetics study of heterogeneous reactions of O3 and SO2 with sea salt single droplets using micro-FTIR spectroscopy: Potential for formation of sulfate aerosol in atmospheric environment.

The heterogeneous reactions of sea salt single droplets with the mixture of O3 and SO2 were studied in real time using microscopic Fourier transform infrared (micro-FTIR) spectrometer. Chemical conversion of SO2 to sulfate and consumption of gaseous HCl occur on the surface of droplets in the presence of O3. The sulfate formation rate and the uptake coefficient are obtained by quantitatively estimating the changes in absorbance area of the sulfate stretching band. In order to further establish a mechanistic framework, we observed the reaction kinetics versus ambient relative humidities (RHs) and droplet sizes. In the view of RH effect, sulfate formation rates are enhanced by about a factor of two on the MgCl2 and ZnCl2 single droplets with increasing RH ranges. High RH is favorable for the sulfate formation because water vapor can trap and activate more gas molecules on the interface of the single droplet. The values of uptake coefficient increase slightly with an increase in single droplet size for the two reaction systems, indicating that the effect of surface adsorption dominates the reactions. Considering the existence of combined pollution with high concentrations of trace gases and sea salt aerosols, as expected in coastal regions, the formation micro-mechanism of sulfate revealed in this work should be incorporated into air quality models to improve the prediction of sulfate concentrations.

High-level l-lysine bioconversion into cadaverine with enhanced productivity using engineered Escherichia coli whole-cell biocatalyst

Cadaverine (also known as 1,5-diaminopentane) is one of the most potential bio-based products with a wide range of industrial applications. Bio-based polyamides configured with cadaverine demonstrated excellent physical properties comparable to conventional petrochemical-based polyamides (polyamides 6 and 66). In this study, recombinant Escherichia coli overexpressing CadA was applied as whole-cell biocatalyst for efficient l-lysine bioconversion into cadaverine. Optimization of the reaction conditions and kinetic study for whole-cell biotransformation was performed by investigating the influence of initial pH (4–8), buffer concentration (0−500 mM), biocatalyst concentration (0.33–1.98 g DCW/L), l-lysine concentrations (1−2 M), and pyridoxal-5’-phosphate concentration (0 to 0.05 mM). Robustness of the constructed biocatalyst was demonstrated with high enzymatic activity over a wide range of pH, stability at acidic pH, and excellent tolerance to high l-lysine concentration. Bioconversion medium without pH adjustment and buffer addition was chosen due to the added benefits of cost efficiency and operation simplification. From the perspective of “green” economy, the whole-cell biocatalyst showed an outstanding efficiency in the bioconversion of l-lysine to cadaverine at high substrate concentration and successfully achieved a cadaverine titer, molar yield and productivity of 1.419 M, 94.6 % and 709.5 mM/h, respectively and the productivity is higher compared to other previous reports. The biocatalyst can be recycled and reused at least three times with over 71.8 % of its original bioconversion efficiency.

Sodium sulfite as an oxygen scavenger for the corrosion control of mild steel in petroleum refinery wastewater: optimization, mathematical modeling, surface morphology and reaction kinetics studies

Corrosion protection of mild steel in simulated refinery wastewater solution (2 wt% MgCl2) by sodium sulfite, as oxygen scavenger inhibitor type, was studied at different temperatures, inhibitor concentrations, rotational velocities and exposure times using weight loss and electrochemical techniques. Oxygen concentrations were also monitored at initial and final conditions. The corrosion inhibition process was optimized by 24 full factorial experimental designs. Optimum conditions of minimum corrosion rate were 40 °C, 40 ppm, 1250 rpm, and 6 h for temperature, inhibitor concentration, rotational velocity, and exposure time. Oxygen levels were reduced by the addition of the scavenger. The amount of oxygen reacted and removed during the corrosion process was evaluated and mathematical relationships were obtained. Electrochemical measurements showed that the corrosion potential shifted to the more active direction and corrosion current decreased with the addition of scavenger. Surface morphology investigations proved that the addition of SS prevents the steel surface damages.

Reaction kinetic study of nonthermal plasma continuous degradation of acetone in a closed-loop reactor

Nonthermal plasma (NTP) degradation has been shown to be a promising method for volatile organic compounds (VOCs) removal from air. However, there have been few studies on the degradation of indoor VOCs using NTP, and even less on their reaction kinetics. In this study, NTP degradation of acetone, a representative of oxygenated VOCs, in a closed-loop reactor operating in recirculation mode was investigated. Acetone and organic by-products were characterized in real-time by proton transfer reaction time-of-flight mass spectrometry. The results showed that approximately 85.7% of the acetone degraded within 7.5 h with dielectric barrier discharge treatment at 4.3 W. Methanol, acetaldehyde, formic acid, and acetic acid were observed to be the main organic byproducts with concentrations time-dependent on the order of ppb/ppm. The concentrations of the inorganic by-products O3 and NO2 are also time-dependent and can decrease to nearly 0 after a sufficient degradation time. Based on the concentration measurement in real-time, several rate laws were used to fit the concentration variations of acetone and the organic by-products, and it was observed that they strictly followed the simple kinetic reaction rate laws: acetone followed the first-order rate law, and formic acid formation followed the one-half-order rate law, etc. This study provides a good example of characterizing NTP removal of VOCs in airtight spaces and has important theoretical and practical significance in designing a better NTP device, predicting NTP degradation reaction rate, and accelerating the practical application of NTP technology for indoor air treatment.

Potential of model cakes to study reaction kinetics through the dynamic on-line extraction of volatile markers and TD-GC-MS analysis

This study presents a novel strategy for the dynamic analysis of volatile compounds extracted from baking vapors using a fit-for-purpose model cake. This model imitates a real sponge cake in terms of structure and processing but it is not reactive towards Maillard and caramelization reactions. When implemented with precursors (glucose (G) or glucose + leucine (G + L)), the reactions are activated and volatile markers can be monitored dynamically during baking. A method for the on-line sampling of vapors during baking using sorbent tubes coupled to thermal desorption (TD-GC-MS) has been developed and proven to be an appropriate and rapid technique to analyze a large number of volatile compounds within a broad range of physical and chemical characteristics. Volatile markers such as acetic acid, furfural, furfuryl alcohol and 5-hydroxymethylfurfual were identified using both models: glucose (G) and glucose + leucine (G + L) because they arise from both caramelization and the Maillard reaction. On the other hand, 3-methylbutanal and 2,5-dimethylpyrazine were only identified in the (G + L) model cake as they arise from the Strecker degradation pathway induced by the presence of leucine. Moreover, the relative abundance of all markers of reactions covers a broad range. On-line sampling coupled to TD-GC-MS enabled the collection of kinetic data on these markers throughout the baking operation and discrimination of the two formulas (G vs G + L) and two baking temperatures (170 °C and 200 °C) used. These results offer promise for the further use of this approach to study reaction kinetics in model cakes.

The synthesis of polymeric dyes based on waterborne polyurethane: a reaction kinetics study using UV absorption spectroscopy

The preparation of waterborne polyurethane based polymeric dyes (DWPU) with anthraquinone chromophores was monitored by using UV absorption spectroscopy for the first time.

Total Iron Measurement in Human Serum With a Novel Smartphone-Based Assay.

Background: Abnormally low or high blood iron levels are common health conditions worldwide and can seriously affect an individual’s overall well-being. A low-cost point-of-care technology that measures blood iron markers with a goal of both preventing and treating iron-related disorders represents a significant advancement in medical care delivery systems. Methods: A novel assay equipped with an accurate, storable, and robust dry sensor strip, as well as a smartphone mount and (iPhone) app is used to measure total iron in human serum. The sensor strip has a vertical flow design and is based on an optimized chemical reaction. The reaction strips iron ions from blood-transport proteins, reduces Fe(III) to Fe(II), and chelates Fe(II) with ferene, with the change indicated by a blue color on the strip. The smartphone mount is robust and controls the light source of the color reading App, which is calibrated to obtain output iron concentration results. The real serum samples are then used to assess iron concentrations from the new assay, and validated through intra-laboratory and inter-laboratory experiments. The intra-laboratory validation uses an optimized iron detection assay with multi-well plate spectrophotometry. The inter-laboratory validation method is performed in a commercial testing facility (LabCorp). Results: The novel assay with the dry sensor strip and smartphone mount, and App is seen to be sensitive to iron detection with a dynamic range of 50 – n}{}300~mu text{g}n/dL, sensitivity of 0.00049 a.u/n}{}mu text{g}n/dL, coefficient of variation (CV) of 10.5%, and an estimated detection limit of n}{}sim 15~mu text{g}n/dL These analytical specifications are useful for predicting iron deficiency and overloads. The optimized reference method has a sensitivity of 0.00093 a.u/n}{}mu text{g}n/dL and CV of 2.2%. The correlation of serum iron concentrations (N = 20) between the optimized reference method and the novel assay renders a slope of 0.95, and a regression coefficient of 0.98, suggesting that the new assay is accurate. Last, a spectrophotometric study of the iron detection reaction kinetics is seen to reveal the reaction order for iron and chelating agent. Conclusion: The new assay is able to provide accurate results in intra- and inter- laboraty validations, and has promising features of both mobility and low-cost manufacturing suitable for global healthcare settings.

Reaction pathways and kinetics study on a syngas combustion system: CO + HO2 in an H2O environment.

The reaction between CO and HO2 plays a significant role in syngas combustion. In this work, the catalytic effect of single-molecule water on this reaction is theoretically investigated at the CCSD(T)/aug-cc-pV(D,T,Q)Z and CCSD(T)-F12a/jun-cc-pVTZ levels in combination with the M062X/aug-cc-pVTZ level. Firstly, the potential energy surface (PES) of CO + HO2 (water-free) is revisited. The major products CO2 + OH are formed via a cis- or a trans-transition state (TS) channel and the formation of HCO + O2 is minor. In the presence of water, the title reaction has three different pre-reactive complexes (i.e., RC2: COHO2 + H2O, RC3: COH2O + HO2, and RC4: HO2H2O + CO), depending on the initial hydrogen bond formation. Compared to the water-free process, the reaction barriers of the water-assisted process are reduced considerably, due to more stable cyclic TSs and complexes. The rate constants for the bimolecular reaction pathways CO + HO2, RC2, RC3, and RC4 are further calculated using conventional transition state theory (TST) with Eckart asymmetric tunneling correction. For reaction CO + HO2, our calculations are in good agreement with the literature. In addition, the effective rate constants for the water-assisted process decrease by 1-2 orders of magnitude compared to the water-free one at a temperature below 600 K. In particular, the effective rate constants for the water-assisted and water-free processes are 1.55 × 10-28 and 3.86 × 10-26 cm3 molecule-1 s-1 at 300 K, respectively. This implies that the contribution of a single molecule water-assisted process is small and cannot accelerate the title reaction.

Benchmark Quantum Kinetics at Low Temperatures toward Absolute Zero and Role of Entrance Channel Wells on Tunneling, Virtual States, and Resonances: The F + HD Reaction

This paper reports a study of the quantum reaction dynamics and kinetics of the F + HD reaction at low and ultralow temperatures, focusing on the range from the Wigner limit up to 50 K. Close coupling time-independent quantum reactive scattering calculations for the production of HF and DF molecules have been carried out on two potential energy surfaces differing in the description of the reaction entrance channel. This case is computationally more demanding than the cases of F with H2 and D2 ( De Fazio et al. Frontiers in Chemistry 2019 , 7 , 328 ) but offers a wider phenomenology regarding the roles of quantum mechanical effects of tunneling, of virtual states, and of resonances. The results show that at the temperatures in the cold and ultracold regimes small changes in the entrance channel long-range interaction induce surprising near threshold features. The presence of a virtual state close to the reactive threshold gives rise to a marked anti-Arrhenius behavior of the rate constants below 100 mK. This effect enhances reaction rates by about 2 orders of magnitude, making them of the same order as those at room temperature and confining the onset of the Wigner regime in the microkelvin region.

Synthesis of three-dimensional nitrogen doped meso/macroporous carbon beads for heterogeneous catalytic solvent-free oxidation of ethylbenzene

A series of nitrogen doped 3D hierarchically porous carbon beads with size of 0.6–0.9 mm are successfully prepared by one-step pyrolysis of dicyandiamide and macroporous resin under different ratio. Dosage of dicyandiamide can effectively control shrinkage of resins during pyrolysis, and favor to create 3D interconnected pore channels and abundant nitrogen doped sites as a self-sacrificing dopant and activating-like agent. The beads display excellent conversion for ethylbenzene to acetophenone as opposed to only calcinating pristine IRA resins (83.5% vs 12.1%), when the ratio reach 1:1. At initial reaction period, linear relationships between concentration of reactants and products are established to evaluate whether the beads are provided with diffusion limitation in mentioned reaction. Structural characterization and reaction kinetic studies indicate that the larger mesoporous pore volume and more meso/macro-pore structure of the beads can expose more accessible active sites and lower diffusion limitation, significantly affecting the initial rates, thereby improving the catalytic performance. In addition, macro-beads in size of millimeter scale can effectively exert the advantages of easy separation and recovery. A new strategy is provided which can keep the diversity of pore scale in porous carbonous precursors during pyrolysis, thereby more effectively applying in heterogeneous catalysis.

How to Measure the Reaction Performance of Heterogeneous Catalytic Reactions Reliably

Ding Ma is a professor of Peking University. He is an advisory member for various journals, has been Associate Editor for the catalysis journal of RSC, Catalysis Science & Technology, since 2014, and was elected as a Fellow of the Royal Society of Chemistry in 2016. His research interests are heterogeneous catalysis, especially those related with energy issues, including C1 chemistry (methane, CO2, and syngas conversion), new reaction routes for sustainable chemistry, and the development of an in situ spectroscopic method that can be operated at working reaction conditions to study reaction mechanisms. Bingjun Xu is an Associate Professor in the Department of Chemical and Biomolecular Engineering at University of Delaware. He received his PhD in Physical Chemistry, advised by Prof. Friend, from Harvard University in 2011 and worked with Prof. Davis at Caltech as a postdoctoral researcher. The overarching goal of Xu research group is to develop innovative strategies to produce renewable electricity, fuels, and chemicals by the rational design of efficient thermo- and electro-catalytic processes. A special focus is placed on the mechanistic understanding of surface-mediated reactions by employing and developing state-of-the-art spectroscopic and kinetic techniques. Meng Wang is a Research Scientist in the College of Chemistry and Molecular Engineering at Peking University. He received his PhD in Chemistry from Technical University of Munich, advised by Prof. Lercher, in 2018 and worked in Pacific Northwest National Laboratory as a Research Associate from 2015 to 2019. Wang’s principal research task focuses on deciphering the kinetic and mechanistic pathways for catalytic reactions by combining reaction kinetics, isotopic experiments, and various in situ characterization methods. Mengtao Zhang is a PhD student in the College of Chemistry and Molecular Engineering at Peking University (Prof. Ding Ma). He received his BS (Chemistry) from Nanjing University in 2015. His research interests include water activation and hydrogen production, CO2 and other greenhouse gas conversion into desirable chemicals, design and development of new catalysts, and operando reaction mechanism and kinetics study.

Rapid Hydrolysis of Organophosphates Induced by U(IV) Nanoparticles: A Kinetic and Mechanistic Study using Spectroscopic Analysis

The heterogeneous interactions of colloidal U particles with organophosphates, leading to the formation of U-phosphate minerals, can retard the migration of U in contaminated sites. Here, we studied the hydrolytic mechanism of p-nitrophenyl phosphate (NPP) on the surfaces of tetravalent uranium nanoparticles (U(IV)NPs), resulting in the formation of U-phosphate precipitates. Our study shows that the reaction rate of NPP hydrolysis is significantly enhanced by U(IV)NPs through a multi-step heterogeneous reaction on the particle surfaces. The end products of the reaction were identified as U(IV)NPs-aggregates with surface-bound phosphates. Colloidal properties, such as high positive values of the zeta-potential (>+30 mV) and large surface areas of U(IV)NPs due to their unique cluster structures consisting of relatively small primary UO2(cr)-particles, are correlated with their reactivity towards hydrolysis reaction. Reaction kinetic modeling studies using spectrophotometric data indicated the presence of two distinct reaction intermediates as the surface complexes of NPP on U(IV)NPs. We suggest the involvement of the NPP inner-sphere complexes in the rate-determining step based on the results obtained by analyzing the ATR-FTIR spectra and the surface-enhanced infrared absorption of NPP bound to substrate surfaces.

New insights of butadiene production from ethanol: Elucidation of concurrent reaction pathways and kinetic study

• Experimental butadiene production overTa 2 O 5 -SiO 2 . • Development of a kinetic model for the conversion of ethanol into butadiene. • Elaboration of two routes to explain butadiene formation. • Elaboration of a reaction scheme for butadiene and side-products. • Very good agreement between experimental and simulated values for most components. While most papers focuses on catalysts improvement, this paper is about a kinetic model based on a new reaction scheme to explain the transformation of ethanol/acetaldehyde to butadiene and side products. The reaction scheme presented here is more complex than the route usually presented in the literature, i.e. Gorin-Jones route. In order to develop this kinetic model, the reaction scheme is studied by means of fixed bed type catalytic tests using Ta 2 O 5 -SiO 2 catalysts with a temperature range from 320 °C to 370 °C and a constant pressure. The reactor (gas/solid, isothermal and isobaric) is modelled in steady state. It is concluded that the model that includes two different routes of butadiene production is in good agreement with the productions of major products and is necessary to explain the formation of some side products, highlighting a brand new reaction scheme for ethanol-to-butadiene transformation.

An in-depth analysis of some methodical aspects of applying pseudo-adiabatic calorimetry

The Accelerating Rate Calorimeter (ARC) - the first representative of the family of pseudo-adiabatic calorimeters - was designed for assessing reactive hazards of chemical processes. Over time the ARC and similar instruments have found much wider applications such as testing of reactive substances, study of reaction kinetics, design of the emergency relief systems. In all these cases precise knowledge about the current state of the sample is required. There are numerous publications regarding the methodical aspects of pseudo-adiabatic calorimetry but many problems are still waiting for the solution.The aim of this paper is to consider in detail the following serious problems: non-uniformity of the system "sample + bomb"; absence of equilibrium between sample and bomb; variability of thermal inertia; uncertainty of the state of reacting system at the onset.The results presented here demonstrate that in many cases the basic assumptions used for interpretation of adiabatic data can be violated and due attention should be paid to the conditions of an experiment that allow it to remain within the applicability limits of the method.

Influence of Filler Content and Filler Size on the Curing Kinetics of an Epoxy Resin.

In this research, the influences of filler content and filler particle size on the flow-hardening behavior were investigated by a measuring mixer. In order to more reliably assess the observed rheological behavior, isothermal differential scanning calorimetry (DSC) measurements were employed to study the curing kinetics of the compounds. The measured data can be fitted well with Kamal-Sourour’s model modified by the diffusion correlation according to Chern and Poehlein. After that, the influence of filler content and size on the kinetic parameters are presented discussed. The results show that the ultimate glass transition temperature is significantly lower for pure epoxy resin (EP) than for compounds filled with surface-treated glass beads, which have an essential effect on the diffusion-controlled reaction at different curing temperatures. For the surface-treated glass beads used in this study, the reaction speed in the early curing stage is accelerated by increasing filler content or decreasing of filler size. In the later curing stage, the reaction speeds of compounds with higher filler content or smaller fillers reduce more quickly. The study of reaction kinetics indicates that the activation energy Ea1, Ea2, the reaction order m, and n are affected differently by varying filler content and size.

Synthesis and characterization of isophorondiamine-based oligoamides: catalytic effect of amides during the curing of epoxy resins

The aminolysis products of PET could be applied in several fields. The purpose of this study was to explore their use as a dual-purpose component as cross-linkers and catalysts in epoxy curing. PET aminolysis was carried out with 1:1.5 and 1:2 PET/amine ratios to produce amides with different molecular weights. The reaction products were characterized with functional group analysis, NMR, FTIR, MALDI-TOF, and solution viscosimetry. The terephthalamides were dissolved in isophorondiamine and used as cross-linkers. Reaction kinetics studies with DSC, viscosimetry, and quantum chemical computational methods were used to characterize their accelerative effects. Our studies have shown that terephthalamides are active catalyst and their efficiency can be tuned with their molecular weight. The quantum chemical simulations suggested that the terephthalamides are in the same order of magnitude in effectiveness as phenolic accelerators. Consequently, terephthalamides are valued materials that can serve as double-purpose components in epoxy curing.