几种胺类固化剂对环氧树脂固化行为及固化物性能的影响

固化剂结构对环氧树脂的固化行为和固化物性能具有重要影响,本文研究了聚醚胺(D-230)、异佛尔酮二胺(IPDA)和3,3'-二甲基-4,4'-二氨基-二环己基甲烷(DMDC) 3种胺类固化剂与实验室自制的低翻度环氧树脂A进行固化反应.通过薪度分析、红外(FTIR)光谱分析、DSC分析等手段研究了环氧树脂与固化剂反应程度...     

Fully biobased epoxy from isosorbide diglycidyl ether cured by biobased curing agents with enhanced properties

This research focuses on fabricating a one-step nano-generator based on electrospun nanofibrous materials for wearable electronics textiles applications. A nanofibrous structure from Poly (vinylidene fluoride), PVDF, was produced using electrospinning technique. Performances of these structures were evaluated by using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM). Piezoelectric properties of fabricated composites also were evaluated on a self-made system as a function of frequency. Results showed that not only electrospinning process can effectively improve piezoelectric properties of nanofiber mats by changing the crystalline structure (e.g. create the β-phase) compared to PVDF film samples, but also the fibrous structure of these materials interestingly can be used in the wearable electronic textiles. By using a novel approach to fabricate the nanofiber layer along with incorporating the electrodes within the structure of the device, the electrical output was improved as high as 1 volt. These results imply promising applications for various wearable self-powered electrical devices and systems.     

钝化2-乙基-4-甲基咪唑/环氧树脂低温固化体系研究

测定了三种α-甲基丙烯酸钝化2-乙基-4-甲基咪唑固化环氧树脂(EP)体系的凝胶时间及固化反应放热曲线,制定了EP固化体系的固化工艺条件,并对这三种EP固化体系的室温(20℃)储存特性及其浇铸体的综合性能进行了比较。结果表明:这三种EP固化体系均可在80℃时快速固化,浇铸体的固化工艺条件为80℃/4 h;当m(E-51)∶m(Eg-031)∶m(固化剂)=25∶25∶2时,EP固化体系预浸料具有最长的储存期(15 d),是综合性能优良的低成本复合材料制造用基体树脂,其弯曲强度、弯曲模量、冲击强度和热变形温度分别为109.3 MPa、3.0 GPa、7.76 kJ/m2和125℃。     

A comparison of some imidazole catalysts as epoxy curing agents

Some physical properties of epoxy resins cured with 2-substituted imidazoles, e.g., 2-ethyl-4-methylimidazole (EMI-24), and 1-substituted imidazoles, e.g., 1-methylimidazole (MI-1), were studied in order to determine the effect of additional crosslinking that has been proposed to occur with EMI-24. While these catalysts were found to yield identical physical properties in that system, they were found to behave differently when the epoxy resin was flexibilized with a polysulfide rubber. Evidence from infrared (IR) and nuclear magnetic resonance (NMR) spectra proved that imidazoles unsubstituted in the 2-position were being deactivated through their conversion to a dihydroimidazole compound in a proportion related to the amount of polysulfide rubber present. Hence, only imidazoles substituted in the 2-position will cure epoxy–polysulfide rubber systems.     

Study of the isothermal curing of an epoxy prepreg by near‐infrared spectroscopy

The commercial epoxy prepreg SPX 8800, containing diglycidyl ether of bisphenol A, dicyanodiamide, diuron, and reinforcing glass fibers, was isothermally cured at different temperatures from 75 to 110°C and monitored via in situ near‐infrared Fourier transform spectroscopy. Two cure conditions were investigated: curing the epoxy prepreg directly (condition 1) and curing the epoxy prepreg between two glass plates (condition 2). Under both curing conditions, the epoxy group could not reach 100% conversion with curing at low temperatures (75–80°C) for 24 h. A comparison of the changes in the epoxy, primary amine, and hydroxyl groups during the curing showed that the samples cured under condition 2 had lower initial epoxy conversion rates than those cured under condition 1 and that more primary amine–epoxy addition occurred under condition 2. In addition, the activation energy under cure condition 2 (104–97 kJ/mol) was higher than that under condition 1 (93–86 kJ/mol), but a lower glass‐transition temperature of the cured samples was observed via differential scanning calorimetry. The moisture in the prepreg was assumed to account for the different reaction kinetics observed and to have led to different reaction mechanisms. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2295–2305, 2003     

Synthesis of epoxy curing agents containing different ring structures and properties investigation of the cured resins

Two kinds of aliphatic epoxy curing agents containing ring structures were synthesized from rosin acid and isosorbide, respectively. They were cured with diglycidyl ether bisphenol A (DER331) and the ultimate propertied of the cured resins were investigated. For comparison, the petroleum‐based curing agent containing planar benzene ring was synthesized from terephthalic acid. The chemical structures of the synthesized curing agents were identified by Fourier transform‐infrared and H‐nuclear magnetic resonance. The ultimate properties of the cured epoxy resins were investigated by thermogravimetric analysis and dynamic mechanical analysis. Especially, the effects of ring structure on their shape memory properties were studied in terms of shape fixity, shape recovery, and shape recovery time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44219.     

Effect of the structure of curing agents modified by epoxidized oleic esters on the toughness of cured epoxy resins

The aim of this study was to determine the effect of the ester carbon chain length of curing agents modified by epoxidized oleic esters on the toughness of cured epoxy resins. An amine‐terminated prepolymer (i.e., curing agent G) was synthesized from a bisphenol A type liquid epoxy resin and triethylene tetramine. The toughening curing agents (G1 and G2) were prepared by reactions of epoxidized oleic methyl ester and epoxidized oleic capryl ester, respectively, with curing agent G. Fourier transform infrared spectrometry was used to characterize the chemical structure of the curing agents. The effects of the carbon chain length of the oleic ester group in the curing agents on the toughness and other performances of the curing epoxy resins were investigated by analysis of the Izod impact strength, tensile strength, elongation at break, thermal properties, and morphology of the fracture surfaces of the samples. The results denote that the toughness of the cured epoxy resins increased with the introduction of oleic esters into the curing agents without a loss of mechanical properties and that the toughness and thermal stability of the materials increased with increasing ester carbon chain length. The toughness enhancement was attributed to the flexibility of the end carbon chains and ester carbon chains of the oleic esters in the toughening curing agents. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Characteristics of epoxy resin cured with in situ polymerized curing agent

In order to improve the heat resistance of a cured epoxy resin together with reducing the viscosity of the resin composition, an epoxy resin was cured with a curing agent formed from the radical copolymerization of vinyl monomers during the cure process of the epoxy resin. N-phenylmaleimide and p-acetoxystyrene were used as vinyl monomers of the curing agent. The epoxy resin was cured by the insertion reaction of the ester group of the in situ polymerized curing agent and the epoxy group of the epoxy resin. In the cure system of the epoxy and the phenol resins, reduction of the viscosity of the resin composition was achieved by replacing some or all of the phenol resin with these monomers. When all phenol resins were replaced by these monomers, the viscosity of resin composition (0.01 Pa s at 70 °C) decreased by about 1/2000 compared with that of the system with only phenol resin (21 Pa s at 70 °C). The glass transition temperature (T_g) of the cured resin with no phenols was 174 °C, an improvement of 17 °C compared with that of the system cured with only phenol resin. The flexural strength of the new resins remained unchanged.     

端脂肪氨基聚醚/环氧树脂胶粘剂的固化工艺研究

以端脂肪氨基聚醚(AATPE)作为环氧树脂(EP)的固化剂,制备出一种高强度、高韧性的EP胶粘剂。采用动态差示扫描量热(DSC)法和凝胶化理论模型研究了AATPE/EP胶粘剂体系的固化反应特点,并对其固化工艺进行了优化。结果表明:AATPE/EP体系的最佳固化工艺条件为"50℃/6 h→100℃/2 h";在最佳固化工艺条件下制备的固化产物,其固化度为97.14%,并且其力学性能优异。     

红外光谱法鉴定爆炸物

依据爆炸物的种类,介绍了烟火药剂、硝酸钾类爆炸物、硝酸铵类炸药的分离方法。根据化学分离方法进行分离定量,利用红外光谱技术对各爆炸物分离组分进行定性,鉴定爆炸物的种类。     

Effect of microencapsulated curing agents on the curing behavior for diglycidyl ether of bisphenol A epoxy resin systems

Microcapsules containing a curing agent, 2‐phenyl imidazole (2PZ), for a diglycidyl ether of bisphenol A (DGEBA) epoxy resin were prepared by a solid‐in‐oil‐in‐water emulsion solvent evaporation technique with poly(methyl methacrylate) (PMMA) as a polymeric wall. The mean particle size of the microcapsules and the concentration of 2PZ were about 10 μm and nearly 10 wt %, respectively. The onset cure temperature and peak temperature of the DGEBA/2PZ–PMMA microcapsule system appeared to increase by nearly 30 and 10°C, respectively, versus those of the DGEBA/2PZ system because of the increased reaction energy of curing. The former could take more than 3 months at room temperature, whereas the latter was cured after only a week. The values of the reaction order (a curing kinetic parameter) for DGEBA/2PZ and DGEBA/2PZ–PMMA microcapsules were quite close, and this showed that the curing reactions of the two samples proceeded conformably. The curing mechanism was investigated, and a two‐step initiation mechanism was considered: the first was assigned to adduct formation, whereas the second was due to alkoxide‐initiated polymerization. The glass‐transition temperature of DGEBA/2PZ was 165.2°C, nearly 20°C higher than the glass‐transition temperatures of DGEBA/2PZ–PMMA microcapsules and DGEBA/2PZ/PMMA microspheres, as determined by differential scanning calorimetry measurements. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal curing of glass‐epoxy prepregs by luminescence spectroscopy

In this study, we investigated the application of the luminescence spectroscopy technique in steady‐state conditions to study glass fiber‐epoxy F161 prepregs. We conducted this study by comparing the results obtained from the intrinsic fluorescence with Fourier transform near infrared spectroscopy. The extrinsic fluorescence of 9‐anthroic acid (9‐AA) was also used. Fourier transform infrared spectroscopy was also used to characterize the epoxide resin. The prepregs containing 9‐AA and those that did not were heat‐treated at 177°C (F161) for 1100 min at a 2°C/min heating rate. The results obtained by both methods indicated that the crosslinking reaction could be monitored by analysis of the spectral changes of the emission bands of the prepreg and 9‐AA. The intrinsic emission at 320 nm was attributed to the fluorophore group containing the epoxy ring and was used to calculate the conversion degree. The photophysical behavior of the 9‐AA probe indicated a reduction of free volume of the polymeric matrix with curing process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

环氧树脂固化剂研究进展

介绍了近年来环氧树脂固化剂研究的一些最新趋势。     

含BPO/PMDA双固化剂体系聚丁二烯环氧树脂胶粘剂的研究

采用均苯四甲酸酐(PMDA)和过氧化二苯甲酰(BPO)双固化剂固化聚丁二烯环氧树脂(ELPB),制备了ELPB/PMDA/BPO耐高温胶粘剂。研究结果表明,BPO对PMDA固化ELPB体系中环氧基团的固化反应没有影响,但对ELPB体系中双键的固化反应影响显著,并进一步促进了胶粘剂中互穿聚合物网络(IPN)的形成;由于交联密度的提高,ELPB/PMDA/BPO胶粘剂的耐热性能增加(耐热温度提高8℃左右),但固化物的脆性也随之增大,导致对铝/铝合金的剪切强度从15MPa左右降低至13MPa左右。     

生物质环氧树脂固化剂的研究进展

综述了近年来生物质环氧树脂固化剂(BEPCA)的研究进展,主要包括以腰果酚、香兰素、松香、木质素和植物油等作为原料制备的生物质胺类固化剂、生物质酸酐类固化剂和多元酚、羧酸及酯类生物质固化剂等;详细介绍了上述BEPCA的结构、制备方法、合成路线以及其固化产物的性能;最后,总结并展望了BEPCA未来的发展趋势.     

Synthesis of rosin‐based flexible anhydride‐type curing agents and properties of the cured epoxy

BACKGROUND: Although rosin acid derivatives have received attention in polymer synthesis in recent years, to the best of our knowledge, they have rarely been employed as epoxy curing agents. The objective of the study reported here was to synthesize rosin‐based flexible anhydride‐type curing agents and demonstrate that the flexibility of a cured epoxy resin can be manipulated by selection of rosin‐based anhydride‐type curing agents with appropriate molecular rigidity/flexibility. RESULTS: Maleopimarate‐terminated low molecular weight polycaprolactones (PCLs) were synthesized and studied as anhydride‐type curing agents for epoxy curing. The chemical structures of the products were confirmed using ¹H NMR spectroscopy and Fourier transform infrared spectroscopy. Mechanical and thermal properties of the cured epoxy resins were studied. The results indicate that both the epoxy/anhydride equivalent ratio and the molecular weight of PCL diol play important roles in the properties of cured resins. CONCLUSION: Rosin‐based anhydride‐terminated polyesters could be used as bio‐based epoxy curing agents. A broad spectrum of mechanical and thermal properties of the cured epoxy resins can be obtained by varying the molecular length of the polyester segment and the epoxy/curing agent ratio. Copyright © 2009 Society of Chemical Industry     

Molecular orientation in novolac cured epoxy resins as studied by rheo-optical FTIR spectroscopy

The molecular orientation and relaxation behavior was studied by rheooptical FTIR spectroscopy during the uniaxial deformation of epoxy resins prepared from the diglycidyl ether of butanediol and novolacs on the basis of bisphenol A. The investigation of orientation phenomena was performed in both the rubbery and the glassy state of the epoxies. Results are discussed with regard to the respective mechanism of deformation. Moreover, the effect of temperature, strain rate, and the molecular weight of the novolacs used on the orientation behavior and the mechanical properties was studied. A significant influence of these parameters on the molecular deformation behavior was observed. The reversibility of the orientation at temperatures above and below the glass transition temperature was examined. Epoxy films were subjected to successive loading–unloading cycles including elongation, relaxation, and annealing. The investigations show that the orientation is completely reversible in the rubbery state, but it is only partly reversible below the glass temperature. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 247–259, 1998     

腰果酚缩醛胺与环氧树脂的固化反应动力学的研究

在不同升温速率下,用差示扫描量热分析(DSC)研究了腰果酚缩醛胺固化剂(PCD)与环氧树脂的固化反应动力学。通过Kissinger、Crane方程和等转化率的方法求得了其表观活化能E=39.89kJ/mol,固化反应级数n=0.906。     

Behavior of polyamidoamine dendrimers as curing agents in bis‐phenol A epoxy resin systems

Polyamidoamine (PAMAM) dendrimers with different generations (0–5) were investigated as curing agents in epoxy resin systems. Flory's gelation theory and the Avrami equation were used to predict the cure behavior of epoxy resin/PAMAM/imidazole at various temperatures and PAMAM concentrations. The theoretical prediction is in good agreement with the experimental results obtained from the dynamic torsional vibration method. Copyright © 2004 Society of Chemical Industry