低熔点芳香胺环氧固化剂的研究I,DEDDM,MEDDM,DDM的共混物

本文通过苯胺和邻乙基苯胺的混和物加入甲醛缩合得到常温下为液体的３，３＇－二乙基－４，４＇－二氨基二苯甲烷（ＤＥＭＭＤ），３－乙基－４，４＇－二氨基二苯甲烷（ＭＥＤＤＭ）和４，４＇－二氨基二苯甲烷（ＤＤＭ）的三元共混物。紫外光谱，红外光谱，色质联用谱仪均证实了这一结果。并用ＪＳＲ固化仪和热分析仪（ＤＳＣ）对该共混物固化Ｅ－５１环氧树脂的过程进行了跟踪，得到了等温和等速升温反应活化能。最后采用ＴＭＡ及     

低熔点芳香胺环氧固化剂的研究──m－PDA、DDM、MOCA的三元低共熔物作为环氧固化剂的研究

本文通过热分析仪（ＤＳＣ）对４，４＇—二氨基二苯甲烷（ＤＤＭ）、间苯二胺（ｍ—ＰＤＡ）和３，３’—二氯—４，４’—二氨基二苯甲烷（ＭＯＣＡ）按７：１０：３组成共混物的等速升温熔融曲线作了研究，发现它具有最低共熔温度。研究了该低熔共混物固化Ｅ—５１环氧树脂的最佳配比。采用ＪＳＲ固化仪和ＤＳＣ对该低共熔混合物固化Ｅ—５１环氧的过程分别作了恒温和等速升温的观察，得到了二者的反应活化能。最后用ＴＭＡ和ＴＧ法对固化物的耐热性进行了评估。     

MDA的乙酰化改性及其对合成聚脲性能的影响

以4,4＇-二氨基二苯甲烷（MDA）为原料,在冰乙酸和磷酸条件下一步合成得到新型位阻型扩链剂4,4＇-二乙酰胺基二苯甲烷（MMDA）,利用红外光谱和1H-NMR对其结构进行了表征,确定了合成产物的化学结构。将它和端氨基聚醚及4,4＇-二苯甲烷二异氰酸酯（MDI）合成新型聚脲,考察了MDA扩链剂改性对聚脲性能的影响。当MMDA代替MDA合成聚脲时,其凝胶时间由45 s增加到143 s。     

PP/PP-g-GMA/EP共混物的制备与性能!

采用熔融共混的方法,制备了聚丙烯(PP)/甲基丙烯酸缩水甘油酯接枝聚丙烯(PP-g-GMA)/环氧树脂(EP)共混物,研究了固化剂4,4二氨基二苯甲烷(DDM)和相容剂PP-g-GMA对共混过程扭矩的影响,探讨了共混物的力学性能,讨论了EP固化与相容剂对共混物热稳定性与结晶性能的影响。结果表明,加入固化剂和相容剂提高了共混扭矩,加入相容剂提高了共混物的拉伸强度与模量,但降低了断裂伸长率,环氧固化与相容剂提高了共混物的最大分解速率温度和PP的结晶温度。     

含羟基聚酰亚胺改性环氧胶的制备及性能研究

将3,3'-二氨基-4,4'-二羟基联苯(DADHBP)、2,2-双(3-氨基-4-羟基苯基)六氟丙烷(BAH-PFP)和3,3',4,4'-四羧酸二苯醚二酐(ODPA)、3,3',4,4'-四羧酸二苯甲酮二酐(BTDA)单体聚合,再经亚胺化得到含羟基聚酰亚胺(HPI)粉末,采用傅里叶红外光谱对其进行了表征。由HPI、烯丙基双酚A、双马来酰亚胺、2-乙基-4-甲基咪唑与N,N,N',N'-四缩水甘油基-4,4'-二氨基二苯甲烷(TGDDM)共聚反应制得胶粘剂,并对胶粘剂的热性能、力学性能及吸水性进行了研究,结果表明:该胶拉伸剪切强度为21.1 MPa,固化后吸水率为0.49%。通过凝胶化时间法计算胶粘剂的表观活化能为64.5 kJ/mol。     

4,4＇-二氟二苯甲烷的合成研究进展

介绍了4,4＇-二氟二苯甲烷的理化性质、光谱性质及应用。综述了4,4＇-二氟二苯甲烷国内外的合成研究情况。     

4,4′-二氨基二苯甲烷合成的正交试验法研究

以苯胺、甲醛为原料在盐酸催化下合成4,4′-二氨基二苯甲烷。利用正交实验法考察了反应物投料比、转位温度、转位时间对4,4′-二氨基二苯甲烷收率的影响。确定了优化条件为:n(苯胺)∶n(甲醛)=4∶1,转位温度85℃,转位时间30 min。优化条件下所得目标产物收率为90.42%。     

新型环氧树脂固化剂的合成及其环氧胶粘剂

以4,4’-二氨基二苯甲烷为原料,经乙酰化、硝化、酸解、还原、中和5步反应合成得到了一种新型环氧树脂固化剂,即3,3’,4,4’-四氨基二苯甲烷,并通过FT—IR分析及熔点测定对其进行了表征。此外,对改性环氧树脂／3,3’,4,4’-四氨基二苯甲烷体系也作了性能研究。     

混合芳香胺固化环氧树脂的研究

用4,4'-二氨基二苯甲烷(DDM)、4,4'-二氨基二苯砜(DDS)和4,4'-二氨基二苯醚(DDE)三种芳香胺混合固化双酚A型环氧树脂,研究了固化网络的机械性能和热性能,当DDM∶DDS∶DDE质量比为5∶2.5∶1时,可使固化网络的冲击强度得到一定的提高。SEM对固化网络冲击断面的微观结构分析表明,树脂呈韧性断裂。     

德国禁用芳香族氨基化合物及其偶氮染料

1994年7月,德国颁布法令,自1995年起,禁止用联苯胺、4-氨基联苯、4-氯-2-甲基苯胺、2-萘胺、4-氨基-3、2′-二甲基偶氮苯、2-氨基-4-硝基甲苯、对氯苯胺、2,4-二氨基苯甲醚、4,4′-二_氨基二苯甲烷、3,3′-双氯联苯胺、3,3′-二甲氧基联苯胺、3,3′-二甲基联苯胺、3,3′-二甲基-4,4′-二氨基二苯甲烷、3-甲基-6-甲氧基苯胺、4,4′-二氨基-3,3′-二氯二苯甲烷、4,4′-二氨基二苯醚、4,4′-     

硫醇固化剂的合成和应用

硫醇固化剂与环氧树脂的配合物可低温快速固化,广泛应用于胶粘剂领域,目前尚依赖进口。为促进硫醇固化剂的国产化,对硫醇固化剂的制备方法和应用进行了研究。实验表明,选用β-巯基丙酸与季戊四醇在酸性催化剂存在下酯化,然后再与环氧树脂进行扩链反应,可以制得黏度和使用配比均适用的硫醇固化剂,总产率为95%以上。用此固化剂与环氧树脂及叔胺混合后,能在5℃以下数分钟内固化。该合成方法工艺简单,易于控制,制得的硫醇固化剂黏度适中,与环氧树脂相溶性好,低温固化快,固化物无色透明等超过了进口产品。     

环氧固化剂硫脲改性四乙烯五胺的合成及性能研究

用硫脲改性四乙烯五胺合成了环氧树脂固化剂。通过测量初凝时间和接触角,讨论了反应时间、合成温度和单体投料比对固化剂性能的影响。通过热效应法考查了固化剂与环氧树脂的最佳配比。实验结果表明,反应时间为3 h,反应温度为130℃,四乙烯五胺与硫脲的质量比为1.4∶1时,合成的固化剂较好。当m固化剂∶m环氧=1∶4时,胶粘剂能在-5℃/8 d内固化,有效提高固化体系在低温下的固化能力。     

Curing behavior of epoxy resin having hydroxymethyl group

A new type of epoxy resin having hydroxymethyl group was synthesized. This epoxy resin was mixed with commercial epoxy resin in various ratios. The mixed epoxy resins were cured with a mixture of 4,4′-diaminodiphenylmethane and m-phenylenediamine (molar ratio, 6 : 4) as a hardener. Curing behavior of the epoxy resin systems with the hardener was examined by DSC and TG-DSC, and parameters of cure reaction were obtained. Viscoelastic properties of cured resin were studied by dynamic mechanical analyzer. It was found that the higher the amount of epoxy resin having hydroxymethyl group, the lower the activation energy (Ea) and the higher the rate constant (k) were. It was also found that the higher the amount of the epoxy resin having hydroxymethyl group, the better heat resistance the fully-cured resin had. These results were explained as follows: Hydroxymethyl group accelerated an epoxideamine reaction. The crosslinking density of the cured resin was increased because in the hydroxymethyl group occurred a condensation reaction above 200°C.     

Gelcasting of SiC using epoxy resin as gel former

Epoxy resin was used as gel former in SiC gelcasting. A hardener as cross-linker causes a nucleophilic addition reaction of epoxy resin instead of free radical reaction of the acrylamide-based gel former system to avoid oxygen and mould materials (plastic and rubber) inhibition. The gelling behavior of premix solution and slurry was investigated by the change of elastic modulus (G′) changing during gelling. Data show 3.4 wt% hardener in 15 wt% epoxy resin solution to be the optimized content to obtain gel with high-G′. Both the polymerization process and the gelation process depend greatly on temperature, which is beneficial for mixing and casting. Green bodies fabricated with epoxy resin show that rubber do not inhibit in the process.     

Thermal properties of epoxy resins crosslinked by an aminated lignin

Aminated lignin possessing significant amount of reactive amino groups was studied as a curing agent of epoxy resin. Fourier transform infrared spectroscopy results proved the reactivity of the aminated lignin with the epoxy resin. Both appearance features and scanning electron microscopy images indicated that the transparent and homogeneous epoxy resin films could be formed with the aminated lignin less than 40% in the hardener mixture. In addition, thermogravimetric analysis and dynamic thermomechanical analysis results revealed that the epoxy resin cured by aminated lignin had better thermal stability compared with ones cured by a common hardener. The mass loss of the epoxy resin cured by the aminated lignin before 300°C was small around only 2.5%. The T_g (the glass transition temperature) of epoxy resin sample after cured by mixed hardener increased from 79°C to 93°C. The obvious difference (70–84°C) of T_d (the thermal deformation temperature) was also observed from the samples with and without the aminated lignin after cured at a high temperature. POLYM. ENG. SCI., 55:924–932, 2015. © 2014 Society of Plastics Engineers     

MONITORING THE SURFACE TENSION OF REACTIVE EPOXY-AMINE SYSTEMS UNDER DIFFERENT ENVIRONMENTAL CONDITIONS

Two commercially available amine-cured epoxy resin formulations were studied under different environmental conditions with regard to the surface tension evolution using axisymmetric drop shape analysis (ADSA). By employing a new strategy, ADSA was used to monitor simultaneously the surface tension and the density of these reactive mixtures from sessile drops. The kinetics of the bulk reactions were quantified by Fourier transform infrared (FTIR) spectroscopy, and the changes in the molecular composition of the surface region were studied by X-ray photoelectron spectroscopy (XPS).

In both formulations, the surface tension values of the amine hardeners were lower than those of the epoxy resins. For one system, the surface tension of the mixture was similar to the surface tension of the hardener. In this case, the hardener migrates to the surface and determines the surface tension of the mixture, as could be proved by XPS measurements. In the other case, the surface region contained only a very small amount of nitrogen, indicating that the nitrogen-containing groups of the hardener were not enriched in the surface region of this mixture. Its surface tension was similar to that of the pure epoxy resin.

In a controlled argon atmosphere, the surface tension of the reactive epoxy-amine systems considered here changed very little as the curing reaction proceeded. The time-dependent changes of the surface tension of the mixtures were caused by environmental factors, particularly the presence of carbon dioxide and water. Such factors can produce complicated surface tension responses due to surface reactions with the amine hardener. The extent of these changes can be controlled by the migration of the hardener to the surface region.     

Mechanical properties and morphology of epoxidized soyabean‐oil‐modified epoxy resin

Epoxidized soyabean oil (ESO) has been used to toughen epoxy resin cured with an ambient temperature hardener. The ESO was prepolymerized before blending with epoxy resin to obtain modified networks having various concentrations of ESO. The modified networks were also made by blending the ESO with epoxy resin by a one‐stage process. All the modified networks were characterized for their thermal, flexural and impact properties, and compared to the parent epoxy network. The optimum properties were obtained at 20 parts per hundred grams of resin (phr) of ESO. The impact behaviour is explained in terms of morphology observed by scanning electron microscopy. © 2001 Society of Chemical Industry     

Increased flexural modulus and strength in SWNT/epoxy composites by a new fabrication method

A new method for preparing SWNT/epoxy nanocomposites has been developed which involves high shear mixing of the epoxy resin and SWNT and heat treating the mixture prior to introducing the hardener. The glass transition temperature of the epoxy resin is unaffected by the presence of nanotubes. An improvement of 17% in flexural modulus and 10% in flexural strength has been achieved at 0.05 wt% of nanotubes. These improvements in flexural modulus and strength are attributed to good dispersion of the nanotubes and grafting of epoxy resin to SWNT by an esterification reaction.     

Preparation of epoxy resin using n-hexadecane based shape stabilized PCM for applying wood-based flooring

Epoxy resin has excellent characteristics of moisture, low toughness, solvent and chemical resistance, low shrinkage on cure, superior electrical and mechanical resistance properties, and good adhesion to many substrates. In this experiment, we prepared epoxy resin with shape stabilized phase change material (SSPCM) to enhance the thermal properties of epoxy resin. The SSPCM was prepared through the vacuum impregnation method, and the SSPCM/epoxy resin composites were prepared through the shear stirring process and curing process. In the preparation process, the epoxy resin and hardener were mixed in a beaker at a one-to-one ratio. Then, 5, 10, 15, and 20 wt.% of the SSPCM was added to the mixture. The thermal properties and chemical properties of epoxy resin with SSPCM were analyzed from scanning electron microscopy, differential scanning calorimetry, thermal gravimetric analysis, and universal testing machine analyzer. From the analysis, we determined that the prepared epoxy resin with SSPCM has heat storage capacity and high thermal conductivity, compared with the epoxy resin.     

Epoxidized natural rubber/epoxy blends: Phase morphology and thermomechanical properties

Epoxidized natural rubbers (ENRs) were prepared. ENRs with different concentrations of up to 20 wt % were used as modifiers for epoxy resin. The epoxy monomer was cured with nadic methyl anhydride as a hardener in the presence of N,N‐dimethyl benzyl amine as an accelerator. The addition of ENR to an anhydride hardener/epoxy monomer mixture gave rise to the formation of a phase‐separated structure consisting of rubber domains dispersed in the epoxy‐rich phase. The particle size increased with increasing ENR content. The phase separation was investigated by scanning electron microscopy and dynamic mechanical analysis. The viscoelastic behavior of the liquid‐rubber‐modified epoxy resin was also evaluated with dynamic mechanical analysis. The storage moduli, loss moduli, and tan δ values were determined for the blends of the epoxy resin with ENR. The effect of the addition of rubber on the glass‐transition temperature of the epoxy matrix was followed. The thermal stability of the ENR‐modified epoxy resin was studied with thermogravimetric analysis. Parameters such as the onset of degradation, maximum degradation temperature, and final degradation were not affected by the addition of ENR. The mechanical properties of the liquid‐natural‐rubber‐modified epoxy resin were measured in terms of the fracture toughness and impact strength. The maximum impact strength and fracture toughness were observed with 10 wt % ENR modified epoxy blends. Various toughening mechanisms responsible for the enhancement in toughness of the diglycidyl ether of the bisphenol A/ENR blends were investigated. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39906.