Synthesis of epoxy resins from alcohol‐liquefied wood and the mechanical properties of the cured resins

New wood‐based epoxy resins were synthesized from alcohol‐liquefied wood. Wood was first liquefied by the reaction with polyethylene glycol and glycerin. The alcohol‐liquefied wood with plenty of hydroxyl groups were precursors for synthesizing the wood‐based epoxy resins. Namely, the alcoholic OH groups of the liquefied wood reacted with epichlorohydrin under alkali condition with a phase transfer catalyst, so that the epoxy groups were put in the liquefied wood. The wood‐based epoxy resins and the alcohol‐based epoxy resins as reference materials were cured with polyamide amine. The glass transition temperature (Tg), the tensile strength, and the modulus of elasticity of the wood‐based epoxy resin were higher than those of the alcohol‐based epoxy resin. Also, the shear adhesive strength of the wood‐based epoxy resin to steel plates was higher than those of the alcohol‐based epoxy resins, which was equivalent to the level of petroleum‐based bisphenol‐A type epoxy resins. The higher Tg of the wood‐based epoxy resin than that of the alcohol‐based epoxy resin is one of the evidences that the wood‐derived molecules were chemically incorporated into the network structures. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

环氧树脂改性有机硅聚合物的合成与应用性能研究

正硅酸乙酯水解可得有机硅聚合物,但产物分子量不高,成膜性差。用环氧树脂对其改性,制得物的涂膜成膜性优良,且大大缩短固化时间。研究了水解温度与时间,催化剂种类,溶剂用量和环氧树脂用量、反应温度与时间对改性物的影响。结果表明,水解温度50℃,时间3h,硫酸催化,乙醇用量35%,环氧树脂用量20%～50%,反应温度50℃,反应时间1h,涂膜性能优良。     

Synthesis of acid anhydride-modified flexible epoxy resins and enhancement of impact resistance in the epoxy composites

Epoxy resins are key materials used in various applications, including coatings, adhesives, and composites. Tougheners, such as nanoparticles, soft polymers, elastomeric polyurethanes, and core/shell particles, have been widely applied to compensate for the brittleness of the epoxy matrix and to enhance the impact resistance. Modifying epoxy resin by reacting it with a flexible component is one of the representative methods to overcome the weakness of cured epoxy polymers upon impact. For introducing flexible parts, we synthesized three types of epoxy-modified resins by reacting acid anhydride with glycidol, followed by reaction with bisphenol [F, S, or J] glycidyl ether to produce flexible modified epoxy resins. Mechanical tests, such as flexural strength and impact resistance tests, were performed by adding various amounts of the synthesized resin to the epoxy composites. The results of these tests suggest that the modified resins were effective in improving the toughness of the epoxy matrix.     

新型含磷环氧树脂的合成及其反应动力学研究

将9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)与邻甲酚醛环氧树脂进行加成反应制得了含磷环氧树脂,并用FT-IR和NMR对其结构进行了表征,确认了该含磷环氧树脂的结构。采用DSC分析方法研究了DOPO与邻甲酚醛环氧树脂的反应动力学,得到两者反应的表观活化能Eα为53.457kJ/mol,反应级数n为0.93。     

Multifunctional epoxy resins: Synthesis and characterization

The tetrafunctional epoxy resins were prepared starting from diaminodiphenylmethane, diaminodiphenylether, and diaminobibenzyl. The obtained resins were characterized by IR and ¹H‐NMR spectroscopy, rheological and thermal techniques. The polymerization reaction was investigated by viscosimetry. The flow activation energy and the polymerization activation energy were evaluated from the rheological data and from the critical parameters (critical time and critical viscosity at gel point). The viscosity measurements and gel time determination showed slight differences between the synthesized resins. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2430–2436, 2000     

聚磷酸盐有机官能团化杂化树脂的合成

采用水-溶剂低热合成方法,通过分子设计合成了一种三聚磷酸钠(STPP)的环氧官能团化杂化树脂(PEHRs),通过分离与提纯,采用薄层色谱法(TLC)、FT-IR、DSC等对杂化材料的结构和热性能进行了初步的表征研究。结果发现,产物是一类结构中既有Me-O-P键构成的线性骨架,又有以P-O-C共价键形式结合的网络结构的新型杂化树脂。其物性特征为透明凝胶状,可溶于N,N-二甲基甲酰胺,软化点为75￣85℃,加热可以熔融,拉伸可以发生取向,并采用甲基纳迪克酸酐(MNA)等固化剂对PEHRs进行固化,杂化树脂的合成和固化的实现表明其具有很高的研究价值和应用前景。     

Synthesis and properties of trifluoromethyl groups containing epoxy resins cured with amine for low Dk materials

The study synthesized a trifluoromethyl (CF₃) groups with a modified epoxy resin, diglycidyl ether of bisphenol F (DGEBF), using environmental friendly methods. The epoxy resin was cured with 4,4′‐diaminodiphenyl‐methane (DDM). For comparison, this study also investigated curing of commercially available diglycidyl ether of bisphenol A (DGEBA) with the same curing agent by varying the ratios of DGEBF. The structure and physical properties of the epoxy resins were characterized to investigate the effect of injecting fluorinated groups into epoxy resin structures. Regarding the thermal behaviors of the specimens, the glass transition temperatures (T_g) of 50–160°C and the thermal decomposition temperatures of 200–350 °C at 5% weight loss (T_d5%) in nitrogen decreased as amount of DGEBF increased. The different ratios of cured epoxy resins showed reduced dielectric constants (D_k) (2.03–3.80 at 1 MHz) that were lower than those of pure DGEBA epoxy resins. Reduced dielectric constant is related to high electrronegativity and large free volume of fluorine atoms. In the presence of hydrophobic CF₃ groups, the epoxy resins exhibited low moisture absorption and higher contact angles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of wood‐based epoxy resins and their mechanical and adhesive properties

Wood‐based epoxy resins were synthesized from resorcinol‐liquefied wood. Wood was first liquefied in the presence of resorcinol with or without a sulfuric acid catalyst at high temperature. Because of the hydroxyl groups, the resorcinol‐liquefied wood was considered as a precursor for synthesizing wood‐based epoxy resin. Namely, the phenolic OH groups of the liquefied wood reacted with epichlorohydrin under alkali condition. By the glycidyl etherification, epoxy functionality was introduced to the liquefied wood. The epoxy functionality of the resins was controlled by the concentration of phenolic OH groups in the liquefied wood, which would be a dominant factor for crosslink density and properties of the cured epoxy resins. The flexural strength (150–180 MPa) and the modulus of elasticity (3.2 GPa) of the highly crosslinked wood‐based epoxy resin were equivalent to those of the commercially available epoxy resin, diglycidyl ether of bisphenol A (DGEBA). Also, the shear adhesive strength of the wood‐based epoxy resin was higher than that of DGEBA when plywood was used as the adhesive substrates. The mechanical and adhesive properties suggested that the wood‐based epoxy resins would be well suited for matrix resins of natural plant‐fiber reinforced composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2285–2292, 2006     

A novel intumescent flame‐retardant epoxy resins system

Pentaerythritol diphosphonate melamine–dicyandiamide–formaldehyde resin salt, a novel macromolecular intumescent flame retardants (IFR), was synthesized, and its structure was a caged bicyclic macromolecule containing phosphorus characterized by IR, NMR and element analysis. The flame retardancy and thermal behavior of a new IFR system for epoxy resin were investigated by LOI, UL‐94 test, TG, and IR. Activation energy for the decomposition of samples was obtained using Kissinger equation. 25% of weight of IFR were doped into epoxy resin to get 27.5 of LOI and UL 94 V‐0. The TG curves and IR spectra show that IFR decreases the initial decomposition temperature and the maximum weight loss rate of epoxy resin, and enhances the thermal stability of epoxy resin at high temperatures and char yield. The activation energy for epoxy resin containing IFR was decreased by 44.8 kJ/mol, which shows that IFR can catalyze decomposition of epoxy resin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

玉米秸秆纤维/环氧树脂复合材料的制备与性能研究

以缩二脲改性的环氧树脂为粘胶剂,玉米秸秆纤维为增强材料,多异氰酸酯为相容剂,丁基缩水甘油醚为稀释剂制备玉米秸秆纤维/环氧树脂复合材料。利用FTIR对其进行结构分析,万能试验机进行力学分析,并研究了玉米秸秆纤维用量对复合材料力学性能和耐水性的影响。结果表明,当粘胶剂质量分数为15%,相容剂与秸秆纤维质量比为1∶3时所制备的复合材料具有良好的力学性能,厚度溶胀率和吸水率较低,是一种性能较为优良的新型环保型复合材料。     

Core-shell particles designed for toughening the epoxy resins. II. Core-shell-particle-toughened epoxy resins

The diglycidyl ether of bisphenol A–m-phenylene diamine (DGEBA–MPDA) epoxy resin was toughened with various sizes and amounts of reactive core-shell particles (CSP) with butyl acrylate (BA) as a core and methyl methacrylate (MMA) copolymerized with various concentration of glycidyl methacrylate (GMA) as a shell. Ethylene glycol dimethacrylate (EGDMA) was used to crosslink either core or shell. Among the variables of incorporated CSP indicated above, the optimal design was to obtain the maximum plastic flow of epoxy matrix surrounding the cavitated CSP during the fracture test. It could be achieved by maximizing the content of GMA in a shell-crosslinked CSP, the particle size, and the content of CSP in the epoxy resin without causing the large-scale coagulations. The incorporation of reactive CSP could also accelerate the curing reaction of epoxy resins. Besides, it was able to increase the glass transition temperature of epoxy resins if the particle size ≤0.25 μm and the dispersion was globally uniform. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2313–2322, 1998     

Synthesis and thermal properties of ester‐type crosslinked epoxy resins derived from lignosulfonate and glycerol

Among various biomass‐based components, both lignin and glycerol are important, since they are abundantly produced as by‐products in industrial processes. Accordingly, in the present study, new types of crosslinked epoxy resins were synthesized from lignin and glycerol. Polymers derived from two types of lignin‐based crosslinked epoxy resins were prepared through two‐step reactions, ester‐carboxylic acid derivative preparation followed by crosslinked epoxy resin preparation, in order to establish a crosslinked epoxy resin system in which glycerol units were included. The resins obtained were labeled as follows: series 1, lignosulfonate‐glycerol polyacid (Ser1LSGLYPA); and series 2, glycerol diglycidyl ether (Ser2GLYDGE). The functional groups of the resins were analyzed using Fourier transform infrared spectrometry. The thermal properties of the resins were analyzed using differential scanning calorimetry and thermogravimetry. The glass transition temperature of the crosslinked epoxy resins increased with increasing LSGLYPA and GLYDGE contents for Ser1LSGLYPA and Ser2GLYDGE, respectively. The thermal degradation temperature for Ser1LSGLYPA and Ser2GLYDGE did not show significant change, suggesting that the crosslinked epoxy resins were thermally stable. The mass residue at 500 °C was not affected by the changes of LSGLYPA and GLYDGE contents. Copyright © 2009 Society of Chemical Industry     

Synthesis and properties of phosphorus containing advanced epoxy resins

A series of advanced epoxy resins with various epoxy equivalent weights were synthesized from a reactive phosphorus‐containing diol, 2‐(6‐oxido‐6H‐dibenz[c,e][1,2]oxaphosphorin‐6‐yl)‐1,4‐dihydroxy phenylene and diglycidyl ether of bisphenol A and then cured with 4,4′‐diaminodiphenyl sulfone, phenol novolac, or dicyandiamide. The parameters of the polymerization reaction (such as reaction time, catalyst) are discussed in this article. Thermal properties of cured epoxy resins were studied using differential scanning calorimetry, dynamic mechanical analysis, and thermal gravimetric analysis. The flame retardancy of cured epoxy resins was tested by limiting oxygen index. The relations between thermal properties, flame retardancy, and epoxy equivalent weights were also studied. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 429–436, 2000     

紫外光固化EA树脂的研制

环氧树脂和丙烯酸在适宜条件下合成EA树脂。讨论了各种反应条件对EA树脂性能的影响。确定了最佳工艺条件 :催化剂A用量 1% ,阻聚剂B用量 1‰～ 3‰ ,在 10 0℃滴加丙烯酸 1 0h～ 1.5h ,滴加完后在 110℃反应约 0 5h ,丙烯酸与环氧树脂的摩尔比为 1 0 4∶1。     

环氧树脂改性超支化聚酯的合成及性能

以偏苯三酸酐、环氧氯丙烷及甲基丙烯酸缩水甘油酯为原料合成了超支化聚酯(HBP),再通过超支化聚合物的羧基与环氧树脂环氧基的反应得到环氧改性超支化聚合物;用GPC1、H-NMR、DSC、TGA表征了环氧改性超支化聚合物的结构和热性能;比较了不同环氧树脂用量改性前后树脂的光反应活性以及光固化涂层的耐擦洗性和硬度,测定了凝胶率-曝光时间曲线;以环氧改性超支化聚合物配制了光刻胶,在混合光源以及接触曝光的条件下,分辨率达到2~3μm,且图像十分清晰,断面整齐。环氧树脂用量为HBP羧基物质量的70%左右时,改性的超支化聚酯的光固化活性有明显提高,力学性能得到明显改进。     

无机纳米粒子填充改性环氧树脂研究进展

介绍了无机纳米粒子的结构,复合机理,用其填充改性环氧树脂复合材料的制备方法,作用机理及研究进展。     

Synthesis,characterization and end-use evaluation of epoxy resins prepared from diallyl and dipropyl bisphenol A

We have synthesized 2,2'(6')-diallyl-4,4'-isopropylidenediphenol (diallyl bisphenol A), 2,2'(6')-dipropyl-4,4'-isopropylidenediphenol (dipropyl bisphenol A), and epoxy resins (glycidyl ether oligomers) of different average molecular weights. The acrylic and methacrylic esters were prepared by reacting the epoxy resin with acrylic and methacrylic acids, respectively. The amine-cured epoxy resins showed promise as general-purpose adhesives, while the epoxy acrylates were found to be useful as reactive oligomers in ultraviolet (UV) radiation curable coatings, and the epoxy methacrylates as anaerobic adhesives.     

Relationship between gelation and morphology of rubber-modified epoxy resins

The addition of both a solid and a liquid rubber to an epoxy resin has been shown to strongly increase the toughness of the material. Moreover, it is well known that toughening depends on the morphology of the system, which, in turn, depends on the cure conditions. In the present work the morphologies of epoxy resins modified with mixtures of solid and liquid rubbers have been studied through transmission electron microscopy. An investigation of the influence of the elastomers and of the gel time on the morphology of the hardened material was carried out. Gel times were evaluated, through rheological measurements, at different cure temperatures.     

新型含氮环氧树脂研究进展

氮系阻燃剂具有高效、低毒(包括其分解产物)等优点,故已成为当今阻燃剂的发展方向。综述了氮系阻燃剂的特点及其阻燃机理,以及目前国内外对含氮环氧树脂(EP)和含氮阻燃固化剂的最新研究进展,并对其发展前景作了展望。