Diethyl ketone‐based imine as efficient latent hardener for epoxy resin

Several imines were synthesized and evaluated as water‐initiated hardener for epoxy resin. Imines with a lower electron density on the C=N carbon showed a faster hydrolysis rate. Diethyl ketone‐based imines were the most efficiently hydrolyzed among the imines examined, and the adhesive properties of epoxy resin with diimines used as the hardeners were evaluated. A novel diethyl ketone‐based diimine, N,N′‐di(1‐ethylpropylidene)‐m‐xylylenediamine (10), served as an efficient latent hardener of epoxy resin. Epikote 828 containing 10, filler, and dryer increased the adhesive strength faster than Epikote 828 containing filler and dryer with methyl isobutyl ketone‐based imine. The mixed system of epoxy resin and 10 showed good storage stability at room temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1744–1749, 2002     

Phosphaphenanthrene‐containing borate ester as a latent hardener and flame retardant for epoxy resin

Borate ester containing the phosphaphenanthrene group with N → B coordination structure (PBN) was synthesized by transesterification of tributyl borate, 2‐(6‐oxido‐6H‐dibenz?c,e??1,2?oxaphos‐phorin‐6‐yl) methanol and N,N‐dimethylethanolamine. A thermally latent curing utility for diglycidyl ether of bisphenol A epoxy resin (E51) was confirmed by differential scanning calorimetry. Additionally, its flame‐retarding function in the cured epoxy was demonstrated in terms of the limiting oxygen index (LOI) and vertical burning test. The cured epoxy with 100:20 mass ratio of E51 to PBN passed UL94 V‐0 rating with 34.3% of LOI. The flame retardation mode and thermal and mechanical properties of the cured epoxy were carefully evaluated. The results of this work suggest that application of PBN would permit the formulation of environmentally friendly one‐pot flame‐retardant epoxy resin. © 2015 Society of Chemical Industry     

Rheological and mechanical properties of DGEBA‐S epoxy copolymer initiated by N‐benzylquinoxalinium hexafluoroantimonate

The rheological and mechanical properties of the DGEBA‐S epoxy copolymer initiated by N‐benzylquinoxalinium hexafluoroantimonate (BQH) as a cationic latent thermal catalyst were investigated. The rheological properties of the DGEBA‐S/BQH system were investigated using a rheometer under isothermal conditions, and the mechanical properties of the casting specimens, involving flexure and impact tests, were also performed. The crosslinking activation energy and mechanical properties of the DGEBA‐S/BQH system were higher than those of the DGEBA/BQH system. This could be attributed to the introduction of sulfone groups with a polar nature to the main chain of the epoxy resins which led to a decrease of molecular motion and an improvement in the toughness of the cured epoxy copolymers. Copyright © 2005 Society of Chemical Industry     

羟基磷灰石增强环氧树脂结构胶的力学性能研究

采用羟基磷灰石(HA)对环氧树脂结构胶进行改性。对改性后结构胶的力学性能进行测试。实验表明:随着HA的掺量增加,环氧结构胶的压缩强度、冲击强度、粘钢剪切强度提高、拉伸强度略有降低;当羟基磷灰石的掺量为5％时。环氧树脂结构胶的压缩强度、冲击强度分别为92MPa、6．8kJ／m2,比纯环氧树脂基体提高28％和70％;当羟基磷灰石的掺量为7％时,环氧树脂结构胶的粘钢剪切强度为26．4MPa．比纯环氧树脂基体提高55％,羟基磷灰石对环氧树脂有较好的增强增韧作用。     

One‐pot curing system of epoxy resin imines initiated with water

The curing and adhesive properties of one‐component epoxy resins containing Epikote 828 and diimines, derived from N,N′‐di(1‐ethylpropylidene)‐m‐xylylenediamine, N,N′‐di(1‐ethylpropylidene)‐1,3‐diaminomethylcyclohexane (2), and N,N′‐di(1,3‐dimethylbutylidene)‐m‐xylylenediamine, which were used as water‐initiated hardeners, were examined. Diethyl ketone‐based imines with a lower electron density on the C?N carbon were efficiently hydrolyzed and showed curing activity. 2, a novel diethyl ketone‐based diimine, served as an efficient latent hardener of the epoxy resin. A paste of the epoxy resin with 2 showed good storage stability at room temperature and good adhesive properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 878–882, 2003     

Improvement of heat resistance and mechanical properties of epoxy resin with nano-Cu-Ni supported RGO

This study reports the synthesis and characterization of epoxy resin/redox graphene/nano-copper-nickel (EP/RGO/Cu-Ni) composites. The RGO/Cu-Ni was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Using dynamic thermodynamic analysis (DMA), the glass transition temperature (Tg) of the modified epoxy resin was increased by 21°C compared to EP. The addition of 1.3 wt% RGO/Cu-Ni to the epoxy matrix resulted in an increase of 79.6% and 161.3% respectively in the tensile strength and impact strength of the new material. Finally, the excellent mechanical properties of EP/RGO/Cu-Ni nanocomposites contribute to the research and development of new high-performance polymer materials.     

液体聚硫聚脲增韧环氧树脂胶粘剂的合成与力学性能

利用异佛尔酮异氰酸酯扩链液体聚硫橡胶，合成了不同硬段含量的液体聚硫聚脲齐聚物，表征了该齐聚物增韧环氧树脂前后巯基含量、环氧含量、粘度及玻璃化温度等变化，并用来增韧环氧树脂-聚酰胺固化体系，研究了增韧环氧树脂的应力应变和粘合强度变化。     

聚氨酯改性环氧树脂胶粘剂的制备及性能研究

由端-NCO基聚氨酯(PU)预聚物与环氧树脂反应,制备了PU接枝改性环氧树脂。着重探讨了PU预聚物的含量、活性稀释剂的含量和异氰酸酯结构等因素,对改性环氧树脂的粘度和粘接性能的影响。实验结果表明,该改性环氧树脂的粘度随着PU预聚物含量的增加而逐渐增大,随着活性稀释剂含量的增加而逐渐降低,而且在相同的条件下,用不同的二异氰酸酯改性环氧树脂的粘度大小次序为:IPDI型>MDI型>TDI型;该改性环氧树脂在PU预聚物含量为20%时,对铝片/铝片的剪切强度最大(7.82 MPa);在PU预聚物含量为10%时,对铁片/铁片的剪切强度最大(11.70 MPa),而且TDI型和IPDI型改性环氧树脂的粘接性能明显好于MDI型改性环氧树脂。     

Morphology and thermomechanical properties of epoxy thermosets modified with polysulfone‐block‐polydimethylsiloxane multiblock copolymer

Polysulfone‐block‐polydimethylsiloxane (PSF‐b‐PDMS) multiblock copolymer was synthesized via the Mannich polycondensation between phenolic hydroxyl‐terminated polysulfone and aminopropyl‐terminated polydimethylsiloxane in the presence of formaldehyde. The multiblock copolymer was characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC) and used as a modifier to improve the thermomechanical properties of epoxy thermosets. Transmission electron microscopy (TEM) showed that the epoxy thermosets containing PSF‐b‐PDMS multiblock copolymer possesses the microphase‐separated morphological structures. Depending on the content of the PSF‐b‐PDMS multiblock copolymer, the spherical particles with the size of 50–200 nm in diameter were dispersed into the continuous epoxy matrices. The measurement of static contact angles showed that with the inclusion of PSF‐b‐PDMS multiblock copolymer, the epoxy thermosets displayed the improved surface hydrophobicity. It is noted that the epoxy resin was significantly toughened in terms of the measurement of critical stress field intensity factor (K_1C). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

ToF‐SIMS investigation of epoxy resin curing reaction at different resin to hardener ratios

Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and principal components analysis (PCA) were used to analyze diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of bisphenol F (DGEBF) epoxy resin blend cured with isophorone diamine (IPD) hardener at different resin to hardener ratios. The aim was to establish correlations between the hardener concentration and the nature and progress of the crosslinking reaction. Insights into the cured resin structure revealed using ToF‐SIMS are discussed. Three sets of significant secondary ions have been identified by PCA. Secondary ions such as C₁₄H₇O⁺, CHO⁺, CH₃O⁺, and C₂₁H₂₄O₄⁺ showed variance related to the completion of the curing reaction. Relative intensities of C_xH_yN_z⁺ ions in the cured resin samples are indicative of the un‐reacted and partially reacted hardener molecules, and are found to be proportional to the resin to hardener mixing ratio. The relative ion intensities of the aliphatic hydrocarbon ions are shown to relate to the cured resin crosslinking density. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Long‐term development of thermophysical and mechanical properties of cold‐curing structural adhesives due to post‐curing

The long‐term changes in the thermophysical and mechanical properties of a cold‐curing structural epoxy adhesive were investigated by accelerating the curing reaction by post‐curing at elevated temperatures. Experimental data concerning the glass transition temperature for periods of up to 7 years and tensile strength and stiffness measurements could be extrapolated for a period of up to 17 years. An existing model for the long‐term development of concrete properties was modified for the prediction of the long‐term mechanical properties of adhesives. The applicability of the acceleration procedure and the new model was confirmed by several verification procedures. Structural adhesives exhibit significant increases in glass transition temperature, strength and stiffness over the long term provided that joints are adequately sealed and protected from humidity and UV radiation. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Curing of DGEBA epoxy resin by low generation amino‐group‐terminated dendrimers

Low generation amino‐group‐terminated poly(ester‐amine) dendrimers PEA1.0 (NH₂)₃ and PEA1.5 (NH₂)₈, and poly(amido‐amine) dendrimer PAMAM1.0 (NH₂)₄ were used as diglycidyl ether of bisphenol A (DGEBA) epoxy resin hardeners. Thermal behavior and curing kinetics of dendrimer/DGEBA systems were investigated by means of differential scanning calorimetry (DSC). Compared with ethylene diamine (EDA)/DGEBA system, the dendrimer/DGEBA systems gradually liberated heat in two stages during the curing process, and the total heat liberated was less. Apparent activation energy and curing reaction rate constants for dendrimer and EDA/DGEBA systems were estimated. Thermal stabilities and mechanical properties of cured thermosetting systems were examined as well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3902–3906, 2006     

Two‐component acrylic structural adhesive initiated by tributylborane for untreated PET adhesion

In order to improve the adhesion strength of acrylic adhesive to untreated poly(ethylene terephthalate) (PET) substrate, two‐component acrylic structural adhesives initiated by tributylborane were prepared. The effects of acrylic monomers, elastomers, decomplexers, and oligomers on the adhesion properties of two‐component acrylic structural adhesive were investigated in sequence. It is found that the shear strength on PET of adhesives toughened by acrylonitrile–butadiene–styrene copolymer and carboxyl‐terminated butadiene–acrylonitrile copolymer is higher than that of commercial adhesives Dp8010NS and Loctite 3030. A tailored oligomer was synthesized from hydroxyl propyl–terminated polydimethylsiloxane and 3‐isopropenyl‐α,α‐dimethylbenzyl isocyanate. It is also noticed that premature failure usually takes place in the lap shear test samples due to the brittleness of the acrylic adhesive, except in the sample of adhesive modified by tailored oligomer. Excellent adhesion to the PET substrate is achieved by this adhesive modified by tailored oligomer, with a lap shear strength above 11 MPa and T‐peel strength up to 5.34 N/mm. Additionally, the resulting adhesive is qualified for the structural bonding of PET materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46612.     

Laboratory investigation of the properties of asphalt modified with epoxy resin

Epoxy asphalts were prepared by mixing styrene–butadiene–styrene (SBS) modified asphalt with epoxy resin. The curing process and morphology of epoxy asphalts were characterized by infrared spectroscopy and fluorescent microscope, respectively. The effects of epoxy resin contents, ratio of curing agent to epoxy resin and curing temperature on properties of epoxy asphalt were investigated. Results indicated that epoxy resin and epoxy asphalt showed similar curing efficiency. Epoxy asphalts can be cured at 120 or 60°C and its viscosity at 120°C can meet the demands of asphalt mixture mixing and paving. The chemical reaction of epoxy resin in epoxy asphalt is slow and reaction occurs not only with the curing agent but also carboxylic acid in epoxy asphalt. The microstructure of epoxy asphalt transforms from the dispersed structure to networks structure with epoxy resin content increasing and phase transition starts when 30 wt % epoxy resin present in asphalt. The softening point and tensile strength of epoxy asphalt increased with epoxy resin contents increasing. The softening point and tensile strength of epoxy asphalt were markedly improved when epoxy resin content was more than 30 wt %, which is attributed to formation of continuous structure of epoxy resin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Anticorrosive properties of epoxy resin coatings cured by aniline/p‐phenylenediamine copolymer

Aniline/p‐phenylenediamine copolymer [poly(ANI‐co‐p‐PDA)] was prepared by chemical oxidative polymerization. FTIR and ¹H‐NMR analysis indicate that the poly(ANI‐co‐p‐PDA) is oligomer with end‐capped amino groups, which can cure epoxy resin. The anticorrosion performance of carbon steel (CS) samples coated by epoxy resin coating cured with poly(ANI‐co‐p‐PDA) and epoxy resin coating cured with triethylenetetramine exposed to 5 wt % NaCl and 0.1 mol/L HCl aqueous solution is studied by the potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that the CS coated by epoxy resin coating cured with poly (ANI‐co‐p‐PDA) has more excellent corrosion protection than that of epoxy resin coating cured with triethylenetetramine. Raman spectroscopy analysis indicates that the surface of CS coated by epoxy resin coating cured with poly(ANI‐co‐p‐PDA) forms passive layer, which is composed of α‐Fe₂O₃. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical properties of poly(styrene‐co‐acrylonitrile)‐modified epoxy resin/glass fiber composites

Poly(styrene‐co‐acylonitrile) was used to modify diglycedyl ether of bisphenol‐A type epoxy resin cured with diamino diphenyl sulfone and the modified epoxy resin was used as the matrix for fiber‐reinforced composites (FRPs) to get improved mechanical properties. E‐glass fiber was used as fiber reinforcement. The tensile, flexural, and impact properties of the blends and composites were investigated. The blends exhibited considerable improvement in mechanical properties. The scanning electron micrographs of the fractured surfaces of the blends and tensile fractured surfaces of the composites were also analyzed. The micrographs showed the influence of morphology on the properties of blends. Results showed that the mechanical properties of glass FRPs increased gradually upon fiber loading. Predictive models were applied using various equations to compare the mechanical data obtained theoretically and experimentally. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

新型脂环族环氧树脂的制备与性能

制备了脂环族环氧树脂——1,2-环己二醇二缩水甘油醚,用傅里叶红外光谱对其结构进行表征,测试了其固化物的热性能、力学性能、电性能。结果表明,1,2-环己二醇二缩水甘油醚具有良好的力学性能和电性能,在电工材料、电子封装领域有广泛的应用前景。     

Influence of aliphatic amine epoxy hardener on the adhesive properties of blends of mono‐carboxyl‐terminated poly(2‐ethylhexyl acrylate‐co‐methyl methacrylate) with epoxy resin

The adhesive properties have been investigated in blends of mono‐carboxyl‐terminated poly(2‐ethylhexyl acrylate‐co‐methyl methacrylate) with diglycidyl ether of bisphenol A and three different aliphatic amine epoxy hardener. The adhesives properties are evaluated in steel alloy substrate using single‐lap shear test. The copolymers are initially miscible in the stoichiometric blends of epoxy resin and hardener at room temperature. Phase separation is noted in the course of the polymerization reaction. Different morphologies are obtained according to the amine epoxy hardener. The most effective adhesive for steel–steel joints in single‐lap shear test is the blends using 1‐(2‐aminoethyl)piperazine (AEP) as hardener. This system shows the biggest lap shear strength. However, the modified adhesives show a reduction in the mechanical resistance. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Control of morphologies and mechanical properties of thermoplastic‐modified epoxy matrices by addition of a second thermoplastic

Ternary mixtures based on stoichiometric mixtures of the diglycidyl ether of bisphenol‐A (DGEBA) and 4,4′‐diaminodiphenyl sulfone (DDS) and two miscible thermoplastics, poly(methyl methacrylate) (PMMA) and the poly(hydroxy ether of bisphenol‐A) (phenoxy), were investigated by optical microscopy (OM), atomic force microscopy (AFM) and dynamic mechanical analysis (DMA). Mechanical testing was used to study the ultimate behavior. All the modified epoxy mixtures were heterogeneous. DMA has been shown to be an excellent technique for detecting the morphologies generated after curing when the loss modulus is used for analysis. Morphology varied with the thermoplastic content on the mixtures. The addition of a second thermoplastic in small amounts changed the morphological features from particulated to co‐continuous and from that to phase‐inverted morphologies. A significant increase in fracture toughness was observed above all for the mixtures with some level of co‐continuity within the epoxy‐rich matrix. Phase inversion led to poor strength and also fracture toughness. Copyright © 2003 Society of Chemical Industry     

Ultraviolet‐curing behavior and mechanical properties of a polyester acrylate resin

Ultraviolet (UV) curing technology has been widely used in many applications because it has several distinct advantages compared to solvent‐based processes or thermal‐curing technology. The effects of photoinitiator types and their contents as well as reactive diluent types and their contents on the UV‐curing behavior and mechanical properties of a UV‐curable polyester acrylate resin were investigated in this study. Three photoinitiators, Irgacure 184, Darocur 1173, and benzophenone, were used in this study. Hexanediol diacrylate, tripropylene glycol diacrylate, and trimethylol propane triacrylate were used as reactive diluents to modify the properties of the acrylate resin. The change of chemical structure during UV curing was monitored by FTIR. A universal testing machine was used to measure the tensile properties of various UV‐cured acrylate films of different compositions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3921–3928, 2004