Grafting and phosphonic acid functionalization of hyperbranched polyamidoamine polymer onto ultrafine silica

In this study, grafting of hyperbranched polyamidoamine (PAMAM) polymer onto ultrafine silica followed by functionalization via the introduction of phosphonic acid groups into the branch ends was performed. First, an initiating site was incorporated into the silica surface by reacting the silica silanol group with 3‐aminopropyltriethoxysilane, producing amino‐functionalized silica. The free amine group content was altered by varying the ratio of methanol to water in the hydrolysis step of the silanization reaction. Grafting of PAMAM was attained by three rounds of sequential Michael addition of silica amino groups to methyl acrylate and amidation of the resulting terminal methyl ester groups with ethylenediamine. Completion of the grafting reaction in each step was clearly confirmed using FTIR analysis. Excessive ethylenediamine and unattached hyperbranched PAMAM present in the reaction product were removed by dialysis with a molecular weight cutoff of 6000–7000 Daltons. However, the amino group content determined in each step was found to be significantly lower than theoretically expected, perhaps indicative of side reactions and, in later stages, steric hindrance. The resultant hyperbranched PAMAM‐grafted onto silica was functionalized by phosphorylation of the terminal amino groups by a Mannich type reaction, producing the phosphorylated hyperbranched PAMAM‐grafted silica. Then its application on cotton fabric to produce fire‐retardant cellulose was tentatively investigated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Comparison of the curing kinetic behavior for two epoxy resin systems containing EPIKOTE 828–EPIKURE 3090 and DURATEK KLM 606A–DURATEK KLM 606B

The aim of the study is to determine the optimum cure temperatures and kinetics for two different epoxy resin systems without using solvent. Two resin systems consist of EPIKOTE 828® epoxy resin–EPIKURE® 3090 polyamidoamine curing agent and DURATEK® KLM 606A epoxy resin–DURATEK® KLM 606B polyamide curing agent. The ratio of resin to curing agent was kept as 1:1 for both the systems. Curing temperatures of both the systems were determined and kinetic parameters were calculated with respect to the experimental results following nth‐order kinetics. Then, a series of isothermal temperatures was applied to the resin systems in order to assess the cure process in terms of conversion, time, and temperature by using differential scanning calorimeter (DSC). The test results of both systems show that the rate of degree of cure for EPIKOTE 828® epoxy resin–EPIKURE® 3090 polyamidoamine curing agent system is approximately 10 times higher than that of DURATEK® KLM 606A epoxy resin–DURATEK® KLM 606B polyamide curing agent system at 230°C. POLYM. COMPOS., 28:762–770, 2007. © 2007 Society of Plastics Engineers     

Dendritic polyamidoamine-grafted halloysite nanotubes for fabricating toughened epoxy composites

Well-dispersed epoxy resin/halloysite nanotubes composites were prepared by functionalization of the HNTs surfaces using polyamidoamine generation-3 (HNTs-G3.0). A series of modified halloysite nanotubes with different generations of dendritic polyamidoamine (PAMAM) were prepared via a divergent synthetic process by repeating the Michael addition of methyl acrylate to superficial amino groups and the amidation of the resulting esters with ethylenediamine. The products were then characterized by means of FTIR, XPS, XRD and TGA. The results showed that PAMAM polymers are successfully grafted on the surface of HNTs and the grafting percentage of HNTs grafted with polyamidoamine generation-3 (HNTs-G3.0) is 27.21 %. The grafted PAMAM has no effect on the crystalline structure of HNTs. The morphology, interfacial interaction and mechanical properties of epoxy composites were investigated and correlated with the surface functionalization of HNTs. The observations of scanning electronic microscopy and transmission electron microscopy images showed that HNTs-G3.0 exhibited better dispersion than the p-HNTs. The interfacial interaction of the epoxy composites was studied by FTIR and DMA. It was found that dendritic polyamidoamine graft can effectively improve the interfacial interaction of the epoxy composites. With the improvement in particle dispersion and interfacial interaction through polyamidoamine generation-3 grafting, an increase of impact strength and fracture toughness was achieved, accompanied by enhancements of flexural strength and modulus. In particular, the impact strength and fracture toughness (K _IC) of composites with polyamidoamine generation-3 grafted HNTs were about 160 and 20 % higher than the values of functionalization halloysite nanotube system.     

Poly(ester‐amine) hyperbranched polymer as toughening and co‐curing agent for epoxy/clay nanocomposites

The marriage between hardness and flexibility of epoxy resins (improved toughness) is a desired feature, which broads their application in various industrial fields, especially for high impact resistance purposes. Accordingly, this work aims to improve toughness properties of epoxy resin (Epon‐828)/Ancamine (curing agent) system using amino‐terminated hyperbranched poly(ester‐amine) [Poly(PEODA‐NPA)] (HP) as toughening and/or co‐curing agent, in presence of organo‐modified Montmorillonite clay (OMMT) as a reinforcing filler. HP was synthesized via Michael addition reaction of poly(ethylene glycol) diacrylate (PEODA) to N‐methyl‐1,3‐propanediamine (NPA). Chemical structure and molecular weight of HP were elucidated using infrared (FTIR) spectroscopy and gel permeation chromatography (GPC) techniques, respectively. Epoxy/OMMT nanocomposites toughened with HP (at different concentrations) showed remarkable improvement in their toughness without any adverse effect on the other physico‐mechanical properties. The optimum concentration of HP and OMMT was found to be 20 wt % and 1–3 wt% of the epoxy resin, respectively. The extent of exfoliation and dispersion of OMMT platelets within the epoxy cured films was assessed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. In addition, thermal gravimetric analyses (TGA‐DTA) of epoxy/OMMT nanocomposites toughened with HP showed a slight increase in their decomposition temperature, particularly at low OMMT loading. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

环氧树脂/改性纳米Y2O3复合材料的固化动力学

利用缩聚反应,通过"一步法"在经过偶联剂处理的纳米氧化钇(Y2O3)粒子表面接枝超支化聚酯,得到超支化聚酯接枝改性纳米氧化钇(Y2O3-g-HBPE)。研究了Y2O3-g-HBPE对环氧树脂非等温固化行为的影响,利用Kissinger和Crane方程研究了固化动力学参数。结果表明,Y2O3-g-HBPE降低了环氧树脂固化反应的活化能,但没有改变环氧树脂的固化机理。     

Preparation of epoxy resin/silica hybrid composites for epoxy molding compounds

Phenolic novolac/silica and cresol novolac epoxy/silica hybrids were prepared through in situ sol‐gel reaction of tetraethoxysilane (TEOS). The formed hybrids were utilized as a curing agent and an epoxy resin in epoxy curing compositions, respectively. Via the two‐step preparation route, the resulting epoxy resin/silica hybrid nanocomposites exhibited good thermal stability, high glass transition temperatures, and low coefficients of thermal expansion. High condensation degree of the condensed silica was observed with a high content of siloxane bridges, p > 85%, measured by ²⁹Si NMR. The two‐step route also provides feasibility of preparation of epoxy resin/silica hybrid nanocomposites compatible with the current processes of manufacturing of epoxy molding compounds. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4047–4053, 2003     

Synthesis of core–shell particles based on hyperbranced polyester and zirconium slag nanoparticles and its influence on the impact resistance of epoxy resin thermosets

Core–shell particles (CSPs) were prepared by hyperbranched polyesters (HBPs), which synthesized by the polycondensation of succinic anhydride and diethanolamine, grafted on zirconium slag nanoparticles (ZSN), a kind of solid waste in zirconium industry. The CSPs were characterized by attenuated total internal reflectance infrared spectroscopy (ATR‐IR), nuclear magnetic resonance spectroscopy (NMR), high resolution transmission electron micrographs (HRTEM), and thermogravimetric analysis (TGA). Then the effect of CSPs on impact enhancement of epoxy resin thermosets modified by HBP with different kinds of functional terminal groups, such as hydroxyl group, epoxide group, and amino group, was studied. The results indicated that the addition of CSPs resulted to a strong interfacial adhesion and thus improve the impact resistance of epoxy resin thermosets. POLYM. COMPOS., 38:441–451, 2017. © 2015 Society of Plastics Engineers     

超支化聚合物在环氧树脂中的应用

综述了超支化聚合物在环氧树脂中的应用,简述了超支化环氧树脂、超支化环氧树脂固化剂和超支化环氧树脂添加剂的合成及应用进展,展望了其研究前景。     

Toughening of an epoxy anhydride resin system using an epoxidized hyperbranched polymer

This paper reports on the use of an epoxidized hyperbranched polymer (HBP) as an additive to an epoxy anhydride resin system. The hyperbranched polymer used was an aliphatic polyester with a molecular weight of around 10 500 g mol^?1. The epoxy resin mixture used was a combination of a difunctional diglycidyl ether of bisphenol A (DGEBA) epoxy and an epoxy novolac, and was cured with a catalysed anhydride curing agent. It has been shown that, at a concentration range of 0 to 20 wt% addition, the HBP is able to almost double the fracture toughness, with little evidence of any deleterious effects upon processing and the durability of the cured resin system. The flexural modulus and stress, however, were found to both decrease by about 30% as a result of HBP addition while the T_g was found to decrease by about 10%. The processability of the uncured resin systems has been investigated by using rheological and calorimetric techniques and it was found that the processability window, as determined by the gel time and viscosity changes, was relatively unaffected by HBP addition. The fracture surfaces were evaluated by using scanning electron microscopy which showed that the unique structure of the HBP facilitates an enhanced interaction with the polymer matrix to achieve excellent toughness enhancement of the polymer matrix. The durability of the epoxy network has been investigated via thermogravimetric analysis (TGA) and solvent uptake, and the HBP has been shown to have little systematic deleterious effect upon the degradation temperatures and the total amount of solvent absorbed. Copyright © 2003 Society of Chemical Industry     

一种侧链型液晶聚合物与环氧树脂共混改性研究

设计并合成了一种侧链型液晶聚合物（SLCP），用红外光谱（FTIR），差示扫描量热分析（DSC）和偏光显微镜（POM）对聚合物结构和液晶性能进行表征，探讨其对环氧树脂共混物力学性能的影响，并分析共混物的微相分离结构，结果表明，用T31作固化剂时SLCP对环氧树脂有较好的增强增韧效果，在强度和玻璃化温度不降低的情况下断裂伸长度比未改性固化物最大提高2．6倍，但用三乙醇胺作固化剂时SLCP对环氧树脂改性效果不明显。     

Improving the interfacial and flexural properties of carbon fiber–epoxy composites via the grafting of a hyperbranched aromatic polyamide onto a carbon fiber surface on the basis of solution polymerization

Hyperbranched aromatic polyamide (HBP) was grafted successfully onto carbon fibers (CFs) on the basis of solution polymerization to enhance the interfacial adhesion strength of CF-reinforced epoxy resin composites. The microstructure and interfacial properties of the CFs before and after decoration were researched. The results indicate that HBP was deposited uniformly onto the CFs with γ-aminopropyl triethoxysilane as the bridging agent. The active groups, roughness, and surface energy of the modified fiber [hyperbranched aromatic polyamide grafted carbon fiber (CF–HBP)] increased visibly in comparison with those of the untreated CFs. The CF–HBP composites revealed simultaneous remarkable enhancements (65.3, 34.3, and 84.8%) in their interfacial shear strength, flexural strength, and modulus, respectively; this was attributed to the improvement in the fiber–epoxy interface through enhanced chemical interactions, mechanical interlocking, and wettability. These agreed with the scanning electron microscopy observations from the fracture surface morphologies of the composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47232.     

Immobilization of flame-retardant onto silica nanoparticle surface and properties of epoxy resin filled with the flame-retardant-immobilized silica (2)

To prepare silica nanoparticle having flame-retardant activity, immobilization of flame-retardant onto the surface was investigated. The immobilization of phosphorous flame-retardant was achieved by two-step reactions: (1) introduction of cyclotriphosphazene (PH) groups onto silica nanoparticle by the reaction of terminal amino groups of the surface with hexachlorocyclotriphosphazene and (2) immobilization of bis(4-aminophenoxy)phenyl phosphine oxide (BAPPO) onto silica having PH groups by the reaction of PH groups on the surface with BAPPO. The immobilization of BAPPO was confirmed by FT-IR and thermal decomposition GC–MS. The composite of epoxy resin filled with BAPPO-immobilized silica (Silica–PH–BAPPO) was successfully prepared by heating in the presence of curing agents. Thermal decomposition temperature and glass transition temperature of the epoxy resin filled with Silica–PH–BAPPO was higher than that of epoxy resin filled with untreated silica, free HCTP and BAPPO. Moreover, flame-retardant property of epoxy resin filled with Silica–PH–BAPPO was estimated by limiting oxygen index (LOI). The LOI value of epoxy resin filled with Silica–PH–BAPPO was higher than that of epoxy resin filled with untreated silica, free HCTP and BAPPO. This may be due the fact that char yield of the epoxy resin filled with Silica–PH–BAPPO was higher than that filled with free flame-retardant.     

Viscoelasticity of epoxy resin/silica hybrid materials with an acid anhydride curing agent

The viscoelasticity of epoxy resin/silica hybrid materials manufactured by the sol–gel process with an acid anhydride curing agent was investigated in terms of morphology. Transmission microscopy observations demonstrated that all the prepared hybrid samples had a two‐phased structure consisting of an epoxy phase and a silica phase. The formed silica had either nanosized particles or coarse domains, depending on the catalyst for the sol–gel process. Raman spectroscopy analysis showed that the formed silica had features typical of sol–gel derived silica glass and that the ring‐opening reactions of the epoxy groups developed in the hybrid samples and in the neat epoxy samples. In dynamic mechanical thermal analysis, there were two transition temperatures due to epoxy chain mobility and epoxy network relaxation, through which the moduli changed by nearly 3 orders of magnitude. The hybridization disturbed epoxy network formation but also reinforced the epoxy network with the formed silica, which was characterized by the activation energy of the network relaxation; therefore, the modulus of the rubbery state was correlated to the activation energy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Rheological characterization of UV‐curable epoxy systems: Effects of o‐Boehmite nanofillers and a hyperbranched polymeric modifier

An organo‐modified Boehmite (o‐Boehmite) was used to prepare nanocomposite UV‐curing coatings, based on a cycloaliphatic epoxy resin (3,4‐epoxycyclohexylmethyl‐3′,4′‐epoxycyclohexane carboxylate). A hyperbranched polymer (HBP) based on highly branched polyester, was also added to the resin, with the aim to modify its reactivity, such as a possible route to increase the toughness of the resin. Different amounts of the nanofiller and the HBP, ranging from 5 up to 20 wt % of resin, were dispersed into the resin in the presence of triarylsulfonium hexafluoroantimonate, as a photoinitiator for the UV curing of the resin. The rheological behavior of the formulations produced was studied as function of the shear rate and of the content of each filler using a cone and plate rheometer. A general increase in viscosity was observed with increasing the volume fraction of each filler and a moderate pseudoplastic behavior was observed when o‐Boehmite filler was added. A non‐Newtonian behavior was observed with the incorporation of the HBP. The viscosity of the epoxy/boehmite resin mixtures was analyzed as function of the nanofiller volume fraction. In the case of epoxy/hyperbranched resin mixtures, the Cross equation was used to predict the viscosity of each formulation as a function of the shear rate and an appropriate relationship to predict the viscosity of each formulation as a function of the filler volume fraction, was determined. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

十二胺改性环氧树脂的研究

通过冲击试验机、热变性仪、硬度计和热重分析仪等仪器,研究了十二胺和固化剂(MTHPA)对改性环氧树脂性能的影响。实验结果表明,十二胺可以提高固化物的耐冲击性能,而固化物的硬度和耐热稳定性变化不大。当加入7份十二胺、约70份固化剂时,固化物的冲击强度由纯环氧体系的5.7 kJ/m~2增加到11.4 kJ/m~2,提高幅度超过100%,而耐热性却变化较小。     

端脂肪氨基聚醚改性环氧树脂的性能研究

用自制的一种既含聚醚柔性链段又含苯脂肪氨基刚性链段的端脂肪氨基聚醚(APPEG)作为固化剂对环氧树脂进行增韧改性。扫描电子显微镜和力学性能测试结果表明,固化剂对环氧树脂具有明显的增强、增韧效果,且改性的环氧树脂胶粘剂具有很好的填充性能,填充比高达50%。与羰基铁粉组成的涂层材料具有优异的力学性能和热稳定性能。     

Novel epoxy-silica hybrid coatings by using ethoxysilyl-modified hyperbranched poly(ethyleneimine) with improved scratch resistance

A new hyperbranched poly(ethyleneimine) with ethoxysilyl groups at the chain ends has been synthesized and characterized and then used in epoxy formulations to generate new organic/inorganic hybrid materials. Formulations of different proportions of diglycidylether of bisphenol A and the prepared ethoxysilylated hyperbranched poly(ethyleneimine) were maintained in a thermostatized controlled humidity chamber to form the inorganic silica network by a sol–gel process and then the epoxy resin was cured at higher temperature using 1-methylimidazole as anionic initiator.     

催化剂对环氧树脂/酚类固化剂体系反应性的影响

采用三氟甲磺酸铒和三氟甲磺酸镱作为环氧树脂/酚类固化剂的催化剂,筛选了固化剂的最佳用量,采用胶化时间研究了催化剂的催化活性,并采用差热分析法对环氧树脂/酚类固化剂/三氟甲磺酸铒动力学参数进行了研究。结果表明,酚类固化剂的最佳质量分数为9%(以环氧树脂计),三氟甲磺酸铒的催化活性最强,环氧树脂/酚类固化剂/三氟甲磺酸铒体系的活化能为79.53 kJ/mol,反应级数为0.95。     

球形二氧化硅/环氧树脂复合材料制备与性能表征

以普通角形二氧化硅为原料,采用氧-乙炔火焰法制备出球形二氧化硅。将环氧树脂(E-51)、固化剂(906)、固化促进剂(DMP-30)和球形化前后二氧化硅按照不同的比例经机械搅拌混合、超声分散和升温固化(100℃、2h和150℃、2h)后制备出二氧化硅/环氧树脂复合材料。研究对比球形化前后二氧化硅对环氧树脂浇注体系热学和力学性能的影响。结果表明:球形二氧化硅的加入,提高了环氧树脂的热稳定性,添加量30%时热分解温度达到最大值340℃,球形化后二氧化硅/环氧树脂复合材料热膨胀系数和初始黏度较球形化前明显降低,力学性能得到提高。     

水性环氧树脂固化剂的研究进展

从水性环氧树脂固化剂的改性原理出发,介绍了现有制备胺类水性环氧树脂固化剂技术的三种改性方法,比较了酰胺化多胺、聚酰胺、多胺-环氧加成物等用作水性环氧树脂固化剂的优势与不足之处,并简单地归纳了水性环氧树脂固化剂研究与发展进程。