Cure Kinetics and Thermal Properties of Octa(aminophenyl)-POSS/Bromobisphenol A Epoxy Resin Nanocomposites

The tetrabromobisphenol A epoxy resin (TBBPAER) was synthesized and Octa(aminophenyl) polyhedral oligomeric silsesquioxane (OAP-POSS) was used as a curing reagent of TBBPAER. The cure kinetics, the glass transition temperature, and the flame resistance of OAP-POSS/TBBPAER nanocomposites were investigated. The results show that the curing reaction could be described by the autocatalytic ?esták-Berggren (S-B) model. The average activation energy E _a is 129.59 KJ/mol, the maximal mechanical loss temperature (T _p) is 166°C, when the molar ratio (N _s) of amino group to epoxy group is 0.5. The oxygen index for fire resistance is 46 ～ 49 for different amounts of OAP-POSS.     

Curing Kinetics and Thermal Properties Characterization of o-Cresol-formaldehyde Epoxy Resin and MeTHPA System

The kinetics of the cure reaction for a system of o-cresol-formaldehyde epoxy resin (o-CFER) with 3-methyl-tetrahydrophthalic anhydride (MeTHPA) as a curing agent and N,N-dimethyl-benzylamine as an accelerator was investigated by means of differential scanning calorimetry (DSC). Analysis of DSC data indicated that an autocatalytic behavior showed in the first stages of the cure for the system, which could be well described by the model proposed by Kamal, which includes two rate constants, k₁ and k₂, and two reaction orders, m and n. The activation energy E₁ and E₂ are 195.84 and 116.54 kJmol^?1, respectively. In the later stages, the reaction is mainly controlled by diffusion, and a diffusion, factor, f(α), was introduced into Kamal's equation. In this way, the curing kinetics were predicted well over the entire range of conversion. Molecular mechanism for the curing reaction was discussed. The glass transition temperature T_g was determined by means of torsional braid analysis (TBA). The results showed that T_gs increased with curing temperature and conversion up to a constant value about 367.1 K. The thermal degradation kinetics of the system was investigated by thermogravimetric analysis (TGA), which revealed two decomposition steps.     

Curing and Morphology of BPA Epoxy Resin/LC Epoxy Resin PEPEB Composites

Liquid crystalline epoxy resin (LC epoxy resin) – p-phenylene di{4-[2-(2,3-epoxypropyl)ethoxy]benzoate} (PEPEB) was synthesized. The mixture of PEPEB with bisphenol-A epoxy resin (BPAER) was cured with a curing agent 4,4-diamino-diphenylmethane (DDM). The curing process and thermal behavior of this system were investigated by differential scanning calorimeter (DSC) and torsional braid analysis (TBA). The morphological structure was measured by polarizing optical microscope (POM) and scanning electron microscope (SEM). The results show that the initial curing temperature Ticu (gel point) of this system is 68.1°C, curing peak temperature T _pcu is 102.5°C, and the disposal temperature T _fcu is 177.6°C. LC structure was fixed in the cured epoxy resin system. The curing kinetics was investigated by dynamic DSC. Results showed that the curing reaction activation energy of BEPEB/BPAER/DDM system is 22.413 kJ/mol. The impact strength is increased 2.3 times, and temperature of mechanical loss peak is increased to 23°C than the common bisphenol-A epoxy resin, when the weight ratio of BEPEB with BPAER is 6 100.     

Curing Kinetics of Liquid Crystalline Epoxy Resins Based on Bisphenol-S Mesogen with DDE by Nonisothermal DSC Data

The curing kinetics for a system of Sulfonyl bis(4,1-phenylene)bis[4-(2,3-epoxypro pyloxy)benzoate] (p-SBPEPB) with 4,4′-diaminodiphenyl ether (DDE) were investigated by nonisothermal differential scanning calorimetry (DSC). The dependencies of the apparent activation energy Ea and the conversion α during overall curing reaction were revealed by Ozawa's method. The results shown the Ea decreased drastially from 107 to 75 KJ/mol with α in the initial stages (α = 0–20%), the average apparent activation energy Ea of p-SBPEPB/DDE is 82.81 KJ/mol and was relatively constant in the 0.5 to 0.9 conversion interval. Some parameters were evaluated using the two kinetic models of ?esták–Berggren (S-B) equation and JMA model. The liquid crystalline (LC) phase had formed and was fixed in the system during the curing process.     

DPP环氧树脂的固化反应研究

用红外光谱（IR）及测定环氢值法研究了双戊烯-苯酚环氧树脂（DPP环氧树脂）和两种胺（DDE，MDA）的固化反应，介绍了最佳反应条件。     

UV-Curable Coating of Unsaturated Polyester/Epoxy Resins Containing Polyhedral Oligomeric Silsesquioxanes

UV-curable coating of unsaturated polyester/epoxy resin (UP-ER) modified with methylacryloylpropyl polyhedral oligomeric silsesquioxanes (MAP-POSS) was prepared. The UV-cured process, kinetics, and some properties of coating were investigated. The results show that this coating has a better UV-curing property. The curing reaction can be described by a two-parameter autocatalytic ?esták-Berggren (S-B) model. The mechanical loss peak temperature T _p of curing coating nanocomposites increased with increasing MAP-POSS content and has a highest value when MAP-POSS content is 12%, which is 121.8°C, and higher, about 18.3°C, than a pure UP-ER system. The coating film has lower volume shrinkage than pure UP-ER.     

Curing kinetics of bio‐based epoxy resin based on epoxidized soybean oil and green curing agent

New thermoset with a high bio‐based content was synthesized by curing epoxidized soybean oil (ESO) with a green curing agent maleopimaric acid catalyzed by 2‐ethly‐4‐methylimidazole. Non‐isothermal differential scanning calorimetry and a relatively new integral isoconversional method were used to analyze the curing kinetic behaviors and determine the activation energy (E_a). The two‐parameter ?esták–Berggren autocatalytic model was applied in the mathematical modeling to obtain the reaction orders and the pro‐exponential factor. For anhydride/epoxy group molar ratio equal to 0.7, E_a decreased from 82.70 to 80.17 kJ/mol when increasing the amount of catalyst from 0.5 to 1.5 phr toward ESO. The reaction orders m and n were 0.4148 and 1.109, respectively. The predicted non‐isothermal curing rates of ?esták–Berggren model matched perfectly with the experimental data. © 2016 American Institute of Chemical Engineers AIChE J, 63: 147–153, 2017     

A novel imidazole derivative curing agent for epoxy resin: Synthesis,characterization, and cure kinetic

A novel imidazole derivative (named as EMI‐g‐BGE) was synthesized through the reaction of 2‐ethyl‐4‐methyl imidazole (EMI) and butyl glycidyl ether (BGE) and characterized by elemental analysis, FTIR spectroscopy, and ¹H NMR spectroscopy. The curing kinetic of diglycidyl ether of bisphenol A (DGEBA) epoxy resin with EMI‐g‐BGE as curing agent was studied by nonisothermal DSC technique at different heating rates. Dynamic DSC scans indicated that EMI‐g‐BGE was an effective curing agent of epoxy resin. The apparent activation energy E_a was 71.8 kJ mol^?1 calculated through Kissinger method, and the kinetic parameters were determined by Málek method for the kinetic analysis of the thermal treatment obtained by DSC measurement. A two‐parameter (m, n) autocatalytic model (?esták‐Berggren equation) was found to be the most adequate selected kinetic model. In addition, the predicted curves from the kinetic model fit well with the nonisothermal DSC thermogram. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Kinetics of Curing and Thermal Degradation of POSS Epoxy Resin/DDS System

Polyhedral oligomeric silsesquioxanes epoxy resin (POSSER) was prepared from 3-glycidypropyl-trimethoxysilane (GTMS) and tetramethylammonium hydroxide (TMAH) by hydrolytic condensation. POSSER was characterized using Fourier-transformed infrared spectroscopy (FTIR), ¹H-NMR, and liquid chromagraphy/mass spectrometry (LC/MS). The epoxy value of POSSER is 0.50 mol/100 g. The LC/MS analysis indicated that T₁₀ is the majority and contain some amount of T₈, besides, a trace T₉ also exists. The curing kinetics of POSSER with 4,4′-diaminodipheny sulfone (DDS) as a curing agent was investigated by means of differential scanning calorimetry (DSC). The curing reaction order n is 0.8841 and the activation energy Ea is 61.06 kJ/mol from dynamic DSC analysis. Thermal stability and kinetics of thermal degradation were also studied by thermal gravimetric analysis (TGA). TGA results indicated that the temperature of POSSE/DDS system 5% weight loss is approximately 377.0°C, which is higher by 12.6°C than that of pure POSSER, and the primary degradation reaction (300–465°C) followed first order kinetics; the activation energy of degradation reaction is 75.81 kJ/mol.     

Cure kinetics and catalyzed effect of hydroxyl group of LC diglycidyl ether of bisphenol‐S with aromatic diamines

The curing reactions of liquid crystalline 4,4′‐bis‐(2,3‐epoxypropyloxy)‐sulfonyl‐bis(1,4‐phenylene) (p‐BEPSBP) with 4,4′‐diaminodiphenylmethane (DDM) and 4,4′‐diaminodiphenylsulfone (DDS) were investigated by nonisothermal differential scanning calorimeter (DSC). The relationships of E_a with the conversion α in the curing process were determined. The catalyzed activation of hydroxyl group for curing reaction of epoxy resins with amine in DSC experiment was discussed. The results show that these curing reactions can be described by the autocatalytic ?esták‐Berggren model. The curing technical temperature and parameters were obtained, and the even reaction orders m, n, and ΔS for p‐BEPSBP/DDM and p‐BEPSBP/DDS are 0.35, 0.92, ?81.94 and 0.13, 1.32, ?24.45, respectively. The hydroxyl group has catalyzed activation for the epoxy–amine curing system in the DSC experiment. The average E_a of p‐BEPSBP/DDM is 67.19 kJ mol^?1 and is 105.55 kJ mol^?1 for the p‐BEPSBP/DDS system, but it is different for the two systems; when benzalcohol as hydroxyl group was added to the curing system, the average E_a of p‐BEPSBP/DDM decreases and increases for p‐BEPSBP/DDS. The crystalline phase had formed in the curing process and was fixed in the system. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Curing Characterization of the Bis-salicylaldehyde-triethylenetetramine Nickel (II)/Epoxy System

The curing reaction of epoxy resin and bis-salicylaldehyde-triethylenetetramine nickel (II) (Ni(sal)₂trien) was investigated using differential scanning calorimetry (DSC), UV-vis spectrometer and FT-IR. DSC measurement showed two distinct exothermic peaks on the curing curves, indicating that the reaction consisted of two reactive species. The first peak at low temperature corresponded to the amine-epoxy reaction with the activation energy of 46.85 kJ · mol^?1 and the second peak corresponded to the hydroxyl-epoxy reaction with the activation energy of 74.23 kJ · mol^?1. As the concentration of Ni(sal)₂trien increased, the amine–epoxy reaction was favored, and the temperature of the hydroxyl-epoxy reaction decreased at the same time.     

Novel Epoxy Curing Agents from Epoxy Resin Based Dialdehyde Derivative

Abstract

A series of epoxy based curing agents were synthesised by the reaction of dialdehyde derivative 1, 1′-(1 -methylethylidene) di[4-{ 1-(1-imino-4-benzaldehyde)-2-propanolyloxy}] benzene of epoxy resin with a different aromatic diamines. The dialdehyde derivative was synthesised by the reaction of epoxy resin (DGEBA) with 4-amino benzaldehyde (4-ABA) in presence of triethyl amine (1% by wt. Of resin) as a catalyst. All this curing agents were characterised by their number average molecular weight (Mn), elemental analyses and infrared spectrophotometry (IR). As produced, polymers may act as a epoxy curing agent, the thermal characteristics of the synthesised PK-epoxy resin system were investigated by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).     

Influence of Nano-Inorganic Particles on Properties of Epoxy Nanocomposites

Solution polymerization of Bisphenol-A and Epichlorohydrine gives epoxy resin. Spray pyrolysis technique was found to be promising method for synthesis of nanomaterials like CaCO₃ of different sizes (10, 15, and 18 nm). The nanomaterial (2 to 10 mass % loading) was added at the time of resin formation. Mechanical stirring as well as an ultrasonication technique were used for uniform distribution of nanomaterials inside the resin. The effect of nanomaterials on thermal behaviors like curing time and glass transition temperature (Tg) were studied. Addition of nanomaterials accelerates the rate of curing of epoxy resin during composite formation. Moreover, addition of nanomaterial doesn't show any consequent change in Tg of epoxy composite but cross-linking density changes linearly. The rheological parameters like viscosity and torque were recorded on a Brookfield viscometer and correlated with M = CS^α and τ = κ(γ)ⁿ.     

Ortho-Substituted Ortho-Cresol Novolac Resins as an Epoxy Resin Curing Agent

A series of ortho-substituted ortho-cresol novolac resins were synthesized and used as curing agents for epoxy resins. The chemical structures of different ortho-substituted ortho-cresol novolac resins were investigated by many measurements, such as FT-IR, ¹H NMR, and ¹³C NMR. The results indicated that the ortho-cresol novolac resin with the needed proportion of ortho-substitution was synthesized through the adjustment of the reaction conditions. The studies on the curing kinetics of ortho-cresol novolac epoxy resin cured by different ortho-cresol novolac resins showed that the activation energy was reduced with an increase in the proportion of ortho-ortho methylene bridges.     

Preparation and Characterization of Cured Epoxy Resin with Hexachloro-Cyclo-Triphosphazene

Epoxy resins can exhibit some excellent properties. The basic principle of curing epoxy resins with a curing agent containing multiple amino groups is the crosslinking reaction between active hydrogen atoms from the curing agent and the oxirane groups in the epoxy resin structure. This study deals with the synthesis of derivative of hexachloro-cyclo-triphosphazene (HCCTP) using curing of epoxy resins. The study of our interest is nucleophilic substitution of HCCTP using N-[3-(trimethoxysilyl)propyl]ethylene diamine. The prepared derivative offers two potential advantages over conventional curing systems, namely improving properties during burning.     

Curing behavior of epoxy resins in two‐stage curing process by non‐isothermal differential scanning calorimetry kinetics method

In this research, a new thermal curing system, with two‐stage curing characteristics, has been designed. And the reaction behaviors of two different curing processes have been systematically studied. The non‐isothermal differential scanning calorimetry (DSC) test is used to discuss the curing reaction of two stages curing, and the data obtained from the curves are used to calculate the kinetic parameters. Kissinger‐Akahira‐Sunose (KAS) method is applied to determine activation energy (E_a) and investigate it as the change of conversion (α). Málek method is used to unravel the curing reaction mechanism. The results indicate that the curing behaviors of two different curing stages can be implemented successfully, and curing behavior is accorded with ?esták‐Berggren mode. The non‐isothermal DSC and Fourier transform infrared spectroscopy test results reveal that two different curing stages can be implemented successfully. Furthermore, the double x fitting method is used to determine the pre‐exponential factor (A), reaction order (m, n), and establish the kinetic equation. The fitting results between experiment curves and simulative curves prove that the kinetic equation can commendably describe the two different curing reaction processes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40711.     

Non-isothermal curing kinetics of epoxy/mechanochemical devulcanized ground rubber tire (GRT) composites

The curing behavior of diglycidyl ether of bisphenol A (DGEBA) epoxy and specially ground mechanochemical devulcanized ground rubber tire system (GRT) in the presence of polyoxyalkyleneamine curing agent was investigated by non-isothermal differential scanning calorimetry technique at different heating rates. Scanning electron microscopic-energy dispersive X-ray spectroscopy, and attenuated total reflection infrared spectroscopy were used to characterize the GRT particles. The kinetic parameters of curing process were determined by isoconversional method given by Málek. The average activation energy E _a was found to be 52.3–60.7 and 45–59.2 kJ/mol for neat epoxy amine (Epo am 31) and epoxy/amine with GRT (5 Epo am 31) systems, respectively. It was observed that the presence of GRT in epoxy/amine promotes the curing. A two parameter (m, n) autocatalytic model (SB equation) was found to be the most adequate to describe the cure kinetics of the studied epoxy/GRT system. A dominant catalyzing effect of GRT on the curing reaction was observed which is attributed to the complexity of the reaction at later stages of curing, therefore, it was not possible to model the reaction over the whole range of degree of conversion.     

Nonisothermal cure kinetics and diffusion effect of liquid-crystalline epoxy sulfonyl bis(1,4-phenylene)bis[4-(2,3-epoxypropyloxy)benzoate] resin with aromatic diamine

The curing kinetics of the liquid-crystalline epoxy resin sulfonyl bis(1,4-phenylene)bis[4-(2,3-epoxypropyloxy)benzoate] with 4,4′-diaminodiphenylsulfone was investigated by nonisothermal differential scanning calorimetry. The relationship between the apparent activation energy (E_a) and the conversion was determined, and the effects of the molecular structure and the order of liquid crystallinity on E_a are discussed in detail. Some parameters were evaluated with the autocatalytic kinetic model of the Šesták–Berggren (S–B) equation. The results show that there were some deviations of these simulation curves from the experimental curves at high heating rates and in the late stage of the curing reaction. The diffusion effect in the nonisothermal curing reaction is discussed, and a diffusion factor was proposed and introduced into the S–B equation. Then, a modified S–B equation was created, as follows: , where α is the conversion, t is the time, m and n are reaction orders, K is rate constant, C is the diffusion coefficient, and α_c is the critical conversion. The theoretical simulation curves agreed very well with the experimental data as determined with the modified S–B equation, which may be more useful for describing and predicting the nonisothermal curing reaction kinetics of epoxy resin. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The Preparation and PhysicoChemical Study of Glass,Jute and Hybrid Glass-Jute Bisphenol-C-Based Epoxy Resin Composites

Glass-PA (EC-G-PA), Jute-PA (EC-J-PA), Glass-Jute-Glass (EC-GJG-PA), Jute-Glass-Jute (EC-JGJ-PA) composites of epoxy resin of bisphenol-C (EBC) have been prepared using a hand lay-up technique at 150°C under 27.58 MPa pressure for 6 h by using phthalic anhydride as a curing agent. EC-G-PA, EC-J-PA EC-GJG-PA and EC-JGJ-PA Possess 34, 41, 27 and 21 MPa tensile strength; 34, 27, 19 and 22 MPa flexural strength; 1.9, 1.0, 1.6 and 1.3 kV/mm electric strength and 4.2 × 10¹³, 1.2 × 10⁹, 8.7 × 10¹¹ and 4.0 × 10¹¹ ohm.cm volume resistivity. Hydrolytic stability of the composites was tested against water, 10% aq. HCl and NaCl solutions at 35°C and also in boiling water. The percent water uptake, equilibrium time and diffusivity of the composites have been determined and discussed their possible applications.