Low-temperature fast curable behavior and properties of bio-based carbon fiber composites based on resveratrol

Environmentally friendly materials are an integral part of sustainable chemistry, and bio-based polymer composites are an important class of materials. The manufacture of composites is expected to reduce or even eliminate the use of adjuvants, considering the importance of reducing energy consumption and avoiding health and environmental risks. In this study, a phenyl-containing, polyfunctional, bio-based epoxy resin (TGER) was synthesized, and carbon fiber-reinforced, bio-based epoxy resin composites were fabricated by vacuum-assisted resin infusion using two aromatic amine curing agents, 4,4′-diaminodiphenylmethane (DDM) and 3,3′-diethyl-4,4′-diaminodiphenylmethane (DEDDM). Curing reactions and rheological behavior studies showed that TGER had higher curing reactivity toward DDM and DEDDM than to diglycidyl ether of bisphenol A (DGEBA) and possessed good processability. The results indicated that the resveratrol-based epoxy resin displayed low-temperature fast curing properties. The evaluation of the mechanical properties of the carbon fiber composites showed that the flexural strengths of CF/TGER/DDM and CF/TGER/DEDDM were 520 and 628 MPa, respectively. The initial decomposition temperature of CF/TGER composites is above 200°C. Furthermore, the carbon fiber–reinforced biopolymers possess excellent heat resistance. Therefore, carbon fiber-reinforced, resveratrol-based epoxy resin composites are promising candidates as alternatives to petroleum-based high-performance carbon fiber composites.     

Synthesis of polysiloxane‐type multifunctional flame retardant and its application in epoxy systems

Polymethyl(3‐glycidyloxypropyl)siloxane (PMGS) was synthesized as a flame‐retardant additive, which were cocured with diglycidyl ether of bisphenol‐A (DGEBA) using 4,4′‐diaminodiphenylsulfone as a curing agent. The structure of PMGS was confirmed through Fourier transform infrared and ¹H‐NMR spectra. The cured products were characterized with dynamic mechanical thermal analysis, thermogravimetric analysis, and oxygen index analyzer. With PMGS incorporated, the cured epoxy resin showed better thermal stability, higher limited oxygen index, and higher char yield. At moderate loading of PMGS, the storage modulus and glass transition temperature of the cured epoxy resin based on neat DGEBA were obviously improved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation,curing kinetics,and thermal properties of bisphenol fluorene epoxy resin

Diglycidyl ether of 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) was synthesized to introduce more aromatic structures into an epoxy resin system. The structure of DGEBF was characterized with Fourier transform infrared and ¹H‐NMR. 4,4′‐Diaminodiphenylmethane (DDM) was used as the curing agent for DGEBF, and differential scanning calorimetry was applied to study the curing kinetics. The glass‐transition temperature of the cured DGEBF/DDM, determined by dynamic mechanical analysis, was 260°C, which was about 100°C higher than that of widely used diglycidyl ether of bisphenol A (DGEBA). Thermogravimetric analysis was used to study the thermal degradation behavior of the cured DGEBF/DDM system: its onset degradation temperature was 370°C, and at 700°C, its char yield was about 27%, whereas that of cured DGEBA/DDM was only 14%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Epoxy resin containing the poly(sily ether): Preparation,morphology, and mechanical properties

The poly(sily ether) with pendant chloromethyl groups (PSE) was synthesized by the polyaddition of dichloromethylsilane (DCM) and diglycidylether of bisphenol A (DGEBA) with tetrabutylammonium chloride (TBAC) as a catalyst. This polymer was miscible with diglycidyl ether of bisphenol A (DGEBA), the precursor of epoxy resin. The miscibility is considered to be due mainly to entropy contribution because the molecular weight of DGEBA is quite low. The blends of epoxy resin with PSE were prepared through in situ curing reaction of diglycidyl ether of bisphenol A (DGEBA) and 4,4′‐diaminodiphenylmethane (DDM) in the presence of PSE. The DDM‐cured epoxy resin/PSE blends with PSE content up to 40 wt % were obtained. The reaction started from the initial homogeneous ternary mixture of DGEBA/DDM/PSE. With curing proceeding, phase separation induced by polymerization occurred. PSE was immiscible with the 4,4′‐diaminodiphenylmethane‐cured epoxy resin (ER) because the blends exhibited two separate glass transition temperatures (T_gs) as revealed by the means of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). SEM showed that all the ER/PSE blends are heterogeneous. Depending on blend composition, the blends can display PSE‐ or epoxy‐dispersed morphologies, respectively. The mechanical test showed that the DDM‐cured ER/PSE blend containing 25 wt % PSE displayed a substantial improvement in Izod impact strength, i.e., epoxy resin was significantly toughened. The improvement in impact toughness corresponded to the formation of PSE‐dispersed phase structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 505–512, 2003     

Acetone—Formaldehyde—Phenol based IPNs for Glass Fibre Reinforced Composite Applications

Abstract

Three component IPNs Glass fibre reinforced composites (GRC) have been prepared from acetone-formaldehyde-phenol (AF-P) resin, Diglycedyl ether of bisphenol-A (DGEBA) (a commercial epoxy resin) and methyl methacrylate (MMA) (a vinyl monomer). The curing catalyst hexamethylene tetramine (HMTA) for AF-P, radical initiators 2,2′-azobisisobutyronitrile (AIBN) for MMA and curing catalyst 4,4′-diamino diphenyl methane (DDM) for epoxy resin were employed. All the IPN GRCs were characterized in terms of their resistance to chemical reagents, thermal behaviour (DSC, TGA) and mechanical properties.     

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).     

Cure kinetics and thermal stability of micro and nanostructured thermosetting blends of epoxy resin and epoxidized styrene‐block‐butadiene‐block‐styrene triblock copolymer systems

The compatibility of styrene‐block‐butadiene‐block‐styrene (SBS) triblockcopolymer in epoxy resin is increased by the epoxidation of butadiene segment, using hydrogen peroxide in the presence of an in situ prepared catalyst in water/dichloroethane biphasic system. Highly epoxidized SBS (epoxy content SBS >26 mol%) give rise to nanostructured blends with epoxy resin. The cure kinetics of micro and nanostructured blends of epoxy resin [diglycidyl ether of bisphenol A; (DGEBA)]/amine curing agent [4,4′‐diaminodiphenylmethane (DDM)] with epoxidized styrene‐block‐butadiene‐block‐styrene (eSBS 47 mol%) triblock copolymer has been studied for the first time using differential scanning calorimetry under isothermal conditions to determine the reaction kinetic parameters such as kinetic constants and activation energy. The cure reaction rate is decreased with increasing the concentration of eSBS in the blends and also with the lowering of cure temperature. The compatibility of eSBS in epoxy resin is investigated in detailed by Fourier transform infrared spectroscopy, optical and transmition electron microscopic analysis. The experimental data of the cure behavior for the systems, epoxy/DDM and epoxy/eSBS(47 mol%)/DDM show an autocatalytic behavior regardless of the presence of eSBS in agreement with Kamal's model. The thermal stability of cured resins is also evaluated using thermogravimetry in nitrogen atmosphere. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Properties of Epon 828 resin cured by cyclic phosphine oxide tetra acid

A new phosphorylated epoxy polymer was obtained using Epon 828 resin cured with a phosphorus-containing curing agent, 10-phenylphenoxaphosphine-2,3,7,8-tetracarboxylic acid-10-oxide (PDAC). In addition, compositions of Epon 828 with common curing agents, for example, 4,4′-diaminodiphenylmethane (DDM) and 4,4′-diaminodiphenylsulfone (DDS), were used for making a comparison of its curing reactivity, heat, and flame retardation with that of PDAC. The reactivites of the three curing agents toward Epon 828, as measured by differential scanning calorimetry (DSC), was in the following order: DDM > PDAC > DDS. Through thermal gravimetric analysis evaluation (TGA), the thermal and flame resistance of epoxy polymers were confirmed in this study as capable of being improved through introduction of the cyclic phosphine oxide group into the carboxyl curing agent structure. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1877–1885, 1998     

Synthesis and characterization of diphenylsilanediol modified epoxy resin and curing agent

A series of diphenylsilanediol modified epoxy resins and novel curing agents were synthesized. The modified epoxy resins were cured with regular curing agent diethylenetriamine (DETA); the curing agents were applied to cure unmodified diglycidyl ether of bisphenol A epoxy resin (DGEBA). The heat resistance, mechanical property, and toughness of all the curing products were investigated. The results showed that the application of modified resin and newly synthesized curing agents leads to curing products with lower thermal decomposition rate and only slightly decreased glass transition temperature (T_g), as well as improved tensile modulus and tensile strength. In particular, products cured with newly synthesized curing agents showed higher corresponding temperature to the maximum thermal decomposition rate, comparing with products of DGEBA cured by DETA. Scanning electron microscopy micro images proved that a ductile fracture happened on the cross sections of curing products obtained from modified epoxy resins and newly synthesized curing agents, indicating an effective toughening effect of silicon–oxygen bond.     

Preparation and characterization of 3,3′‐bis (maleimidophenyl)phenylphosphine oxide (BMI)/polysulfone modified epoxy intercrosslinked matrices

An intercrosslinked network of polysulfone (PSF)—bismaleimide (BMI) modified epoxy matrix system was made by using diglycidyl ether of bisphenol A (DGEBA) epoxy resin, hydroxyl terminated polysulfone and bismaleimide (3,3′‐bis(maleimidophenyl) phenylphosphine oxide) with diaminodiphenylmethane (DDM) as curing agent. BMI–PSF–epoxy matrices were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and heat deflection temperature (HDT) analysis. The matrices, in the form of castings, were characterized for their mechanical properties such as tensile strength, flexural strength, and unnotched Izod impact test as per ASTM methods. Mechanical studies indicated that the introduction of polysulfone into epoxy resin improves the toughness to an appreciable extent with insignificant increase in stress–strain properties. DSC studies indicated that the introduction of polysulfone decreases the glass transition temperature, whereas the incorporation of bismaleimide into epoxy resin influences the mechanical and thermal properties according to its percentage content. DSC thermograms of polysulfone as well as BMI modified epoxy resin show a unimodal reaction exotherm. The thermal stability and flame retardant properties of cured epoxy resins were improved with the introduction of bismaleimide and polysulfone. Water absorption characteristics were studied as per ASTM method and the morphology of the BMI modified epoxy and PSF‐epoxy systems were studied by scanning electron microscope. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Structure characterization,reactivity, and thermal properties of new cyclic phosphine oxide epoxy resin containing tetra-oxirane rings

A new type of epoxy resin, which contained cyclic phosphine oxide and tetra-oxirane rings in the main chain, was synthesized. The structure of the new type of epoxy resin was confirmed by elemental analyses (EA), infrared (IR) spectroscopy, and ¹H nuclear magnetic resonance (NMR) and ¹³C-NMR spectroscopies. In addition, compositions of the new synthesized cyclic phosphine oxide epoxy resin (TGCAO) with three curing agents, for example, bis(3-aminophenyl)ethylphosphine oxide (BEMP), 4,4′-diaminodiphenylmethane (DDM), and 4,4′-diaminodiphenylsulfone (DDS) were used for making a comparison of its curing reactivity, heat, and flame retardancy with those of Epon 828 and DEN438. The reactivities were measured by differential scanning calorimetry. Through the evaluation of thermal gravimetric analysis, those polymers, which were obtained through the curing reactions between the new epoxy resin and three curing agents (BEMP, DDM, and DDS), also demonstrated adequate thermal propeties, as well as a high char yield. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1397–1409, 1998     

Biobased epoxy resin derived from eugenol with excellent integrated performance and high renewable carbon content

Developing biobased epoxy resin with high renewable carbon content and outstanding integrated performance is beneficial for both sustainable development and applications in cutting‐edge fields. Herein, a biobased epoxy monomer (TEUP‐EP) with high renewable carbon content (100%) was synthesized from renewable eugenol with a sustainable process; TEUP‐EP was then blended with 4,4′‐diaminodiphenylmethane (DDM) to develop a new biobased epoxy resin (TEUP‐EP/DDM). The integrated performance of TEUP‐EP/DDM resin was studied and compared with that of petroleum‐based diglycidyl ether of bisphenol A (DGEBA)/DDM resin. Compared with DGEBA/DDM resin, TEUP‐EP/DDM resin has much better integrated performance and not only exhibits a glass transition temperature about 26 °C higher and a 24.4% or 57% increased flexural strength or modulus, but also shows outstanding flame retardancy. Specifically, the limiting oxygen index increases from 26.5% to 31.4% and the UL‐94 grade improves from no rating to the V‐0 level; moreover, the peak heat release rate and total heat release decreased by 63.1% and 57.4%, respectively. All these results fully prove that TEUP‐EP/DDM is a novel biobased high performance epoxy resin. The mechanism behind these attractive integrated performances is discussed intensively. © 2018 Society of Chemical Industry     

The synthesis and properties of new epoxy resin containing phosphorus and nitrogen groups for flame retardancy

A new type of epoxy resin, which contained phosphorus oxide and nitrogen groups in the main chain, was synthesized. The structure of the new type of epoxy resin was confirmed by infrared (IR) spectroscopy, ¹H nuclear magnetic resonance (¹H‐NMR), and ¹³C‐NMR spectroscopic techniques. In addition, compositions of the new synthesized epoxy resin (TGDMO) with three curing agents, for example, bis(3‐aminophenyl) methylphosphine oxide (BAMP), 4,4′‐diaminodiphenylmethane (DDM), and 4,4′‐diaminodiphenylsulfone (DDS), were used for making a comparison of its curing reactivity, heat, and flame retardancy with that of Epon 828 and DEN 438. The reactivities were measured by differential scanning calorimetry (DSC). Through the evaluation of thermal gravimetric analysis (TGA), those polymers which were obtained through the curing reactions between the new epoxy resin and three curing agents (BAMP, DDM, and DDS) also demonstrated excellent thermal properties as well as a high char yield. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 413–421, 1999     

Preparation and Application of a New Curing Agent for Epoxy Resin

A new curing agent based on palmitoleic acid methyl ester modified amine (PAMEA) for epoxy resin was synthesized and characterized. Diglycidyl ether of bisphenol A (DGEBA) epoxy resins cured with different content of PAMEA along with diethylenetriamine (DETA) were prepared. The mechanical properties, dynamic mechanical properties, thermal properties, and morphology were investigated. The results indicated that the PAMEA curing agent can improve the impact strength of the cured epoxy resins considerably in comparison with the DETA curing agent, while the modulus and strength of the cured resin can also be improved slightly. When the PAMEA/epoxy resin weight ratio is 30/100, the comprehensive mechanical properties of the cured epoxy resin are optimal; at the same time, the crosslinking density and glass transition temperature of the cured epoxy resin are maximal.     

EP/改性DDM体系的固化反应动力学及性能研究

采用非等温DSC(差示扫描量热)法对EP(环氧树脂)/改性DDM(4,4′-二氨基二苯基甲烷)体系的固化反应过程进行了跟踪。采用Kissinger、Ozawa、Crane和T-β(温度-升温速率)外推法等得到该固化体系的动力学参数和固化工艺条件,并对其力学性能和热变形温度进行了测定。结果表明:EP/改性DDM体系的表观活化能为49.43 kJ/mol,反应级数为0.869,固化条件为"85℃/2 h→125℃/2 h",热变形温度为130℃;与EP/DDM体系相比,该固化体系的表观活化能降低了7.0%,热变形温度下降了16.1%,拉伸强度和压缩强度提高了20%以上,而弯曲强度和弯曲模量基本上保持不变。     

A simple imide compound as a curing agent for epoxy resin. I. Synthesis and properties

A simple imide compound, 4‐amino‐phthalimide (APH), was synthesized as a curing agent for epoxy resin. APH was prepared from the hydration of 4‐nitro‐phthalimide, which was prepared from the nitration of phthalimide. The chemical structure of APH was verified by IR and ¹H‐NMR spectra. The thermal properties and dielectric constant (ε) of a phosphorus‐containing novolac epoxy resin cured by APH were determined and compared with those of epoxy resins cured by either 4,4′‐diamino diphenyl methane (DDM) or 4,4′‐diamino diphenyl sulfone (DDS). The results indicate that the epoxy resin cured by APH showed better thermal stability and a lower ε than the polymer cured by either DDM or DDS. This was due to the introduction of the imide group of APH into the polymer structure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

双(4-胺基苯基)-苯基磷酸酯的合成及其性能研究

以对硝基苯酚和苯基二氯磷酸酯为原料,采用两步法合成了双(4-胺基苯基)-苯基磷酸酯(BAPP)含磷二胺固化剂,用红外光谱法对合成产物进行了分析和表征。固化反应动力学分析表明,BAPP与环氧树脂的反应活性较DDM的反应活性略高。BAPP与环氧树脂的固化产物热失重分析表明,在低温区主要是有机磷化合物的分解,在高温区主要是基体主链的断裂;与DDM的环氧固化产物相比较,BAPP与环氧树脂的固化产物有较高的成炭率,极限氧指数(LOI)为34,BAPP对固化产物的玻璃化温度影响不大。     

Epoxy resin based on 4,4′-dihydroxydiphenysulfone. I. Synthesis and reaction kinetics with 4,4′-diaminodiphenylmethane and 4,4′-diaminodiphenylsulfone

Epoxy resins based on 4,4′-dihydroxydiphenylsulfone (DGEBS) and diglycidyl ether of bisphenol A (DGEBA) were prepared by alkaline condensation of 4,4′-dihydroxydiphenylsulfone (bisphenol S) with epichlorohydrin and by recrystallization of liquid, commercial bisphenol A-type epoxy resin, respectively. Curing kinetics of the two epoxy compounds with 4,4′-diaminodiphenylmethane (DDM) and with 4,4′-diaminodiphenylsulfone (DDS) as well as T_g values of the cured materials were determined by the DSC method. It was found that the ? SO₂? group both in the epoxy resin and in the harener increases T_g values of the cured materials. DGEBS reacts with the used hardeners faster than does DGEBA and the curing reaction of DGEBS begins at lower temperature than does the curing reaction of DGEBA when the same amine is used. © 1994 John Wiley & Sons, Inc.     

Curing kinetics and properties of epoxy resin-fluorenyl diamine systems

Diglycidyl ether of bisphenol fluorene (DGEBF), 9,9-bis-(4-aminophenyl)-fluorene (BPF) and 9,9-bis-(3-methyl-4-aminophenyl)-fluorene (BMAPF) were synthesized to introduce more aromatic structures into the epoxy systems, and their chemical structures were characterized with FTIR, NMR and MS analyses. The curing kinetics of fluorenyl diamines with different epoxy resins including DGEBF, cycloaliphatic epoxy resin (TDE-85) and diglycidyl ether of bisphenol A (DGEBA) was investigated using non-isothermal differential scanning calorimetry (DSC), and determined by Kissinger, Ozawa and Crane methods. The thermal properties of obtained polymers were evaluated with dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The results show that the values of activation energy (E_a) are strongly dependent on the structures of epoxy resin and curing agent. The curing reactivity of epoxy system is restrained by the introduction of rigid fluorene into chain backbone and flexible methyl into side groups. The cured DGEBF/fluorenyl diamine systems exhibit remarkably higher glass transition temperature, better thermal stability and lower moisture absorption compared to those of DGEBA/fluorenyl diamine systems, and display approximate heat resistance and much better moisture resistance relative to those of TDE-85/fluorenyl diamine systems.     

香草醇基环氧树脂的合成、固化动力学及性能

以可再生香草醇为原料,合成了一种生物基环氧树脂（DGEVA）。通过使用甲基六氢苯酐（MeHHPA）作为固化剂,制备了一种新型的生物基环氧树脂交联网络（DGEVA/MeHHPA）。对其非等温固化动力学、热性能、热机械性能、机械性能和微观形貌结构进行了系统的研究,并用商用的石油基双酚A型环氧树脂组成的石油基环氧树脂体系（DGEBA/MeHHPA）进行对比。结果表明：DGEVA/MeHHPA和DGEBA/MeHHPA具有相似的固化反应活性。DGEVA/MeHHPA具有可以与DGEBA/MeHHPA相媲美的综合性能：玻璃化转变温度为82.2℃;拉伸强度和拉伸模量分别是 (66.7±6)MPa和 (2.8±0.1)GPa;T_d5%、T_d10%和T_dmax分别是242.4℃、284.9℃和392.4℃。此外,DGEVA/MeHHPA在形变过程中发生了塑性变形而吸收了更多的断裂能。DGEVA刚性骨架和低分子量带来的潜在高交联密度赋予了DGEVA优异性能,具有在实际应用中替代石油基环氧树脂的应用潜力。