DMA应用于增韧环氧树脂的研究

本文主要应用DMA来研究增韧环氧树脂(CTCPE/DGEBA 24EMI)体系.讨论了CTCPE与DGEBA,24EMI与DGEBA之间的化学反应,还讨论了CTCPE不同分子量和不同用量对体系的动态力学性能的影响.     

Epoxy resin containing the poly(sily ether): Preparation,morphology, and mechanical properties

The poly(sily ether) with pendant chloromethyl groups (PSE) was synthesized by the polyaddition of dichloromethylsilane (DCM) and diglycidylether of bisphenol A (DGEBA) with tetrabutylammonium chloride (TBAC) as a catalyst. This polymer was miscible with diglycidyl ether of bisphenol A (DGEBA), the precursor of epoxy resin. The miscibility is considered to be due mainly to entropy contribution because the molecular weight of DGEBA is quite low. The blends of epoxy resin with PSE were prepared through in situ curing reaction of diglycidyl ether of bisphenol A (DGEBA) and 4,4′‐diaminodiphenylmethane (DDM) in the presence of PSE. The DDM‐cured epoxy resin/PSE blends with PSE content up to 40 wt % were obtained. The reaction started from the initial homogeneous ternary mixture of DGEBA/DDM/PSE. With curing proceeding, phase separation induced by polymerization occurred. PSE was immiscible with the 4,4′‐diaminodiphenylmethane‐cured epoxy resin (ER) because the blends exhibited two separate glass transition temperatures (T_gs) as revealed by the means of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). SEM showed that all the ER/PSE blends are heterogeneous. Depending on blend composition, the blends can display PSE‐ or epoxy‐dispersed morphologies, respectively. The mechanical test showed that the DDM‐cured ER/PSE blend containing 25 wt % PSE displayed a substantial improvement in Izod impact strength, i.e., epoxy resin was significantly toughened. The improvement in impact toughness corresponded to the formation of PSE‐dispersed phase structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 505–512, 2003     

Toughness and reinforcement of diglycidyl ether of bisphenol-A by hyperbranched poly(trimellitic anhydride-butanediol glycol) ester epoxy resin

Hyperbranched epoxy resin shows best comprehensive performance in epoxy resin system and is considered as a kind of toughness and reinforcement additive. This article reports on the use of novel hyperbranched poly(trimellitic anhydride-butanediol glycol) ester epoxy resin (HTBE) prepared by us as a functional additive to an epoxy amine resin system. The effect of molecular weight and content of the HTBE on the performance of the diglycidyl ether of bisphenol-A (DGEBA)/HTBE hybrid resin are discussed in detail, and their performance has maximum with the increase of content and molecular weight of HTBE. The impact strength and fracture toughness of the hybrid resin containing 9 wt% second generation of HTBE are 48.2 kJ/m² and 2.71 MPa m^1/2, and which almost are 2.77 and 1.5 times of DGEBA performance respectively. Furthermore, the tensile and flexural strength can also be enhanced about 17%. The fracture surface micrograph of hybrid resin shows no microphase separation of the HTBE/DGEBA blends that facilitates an enhanced interaction to achieve excellent toughness and strength enhancement of the cured systems by scanning electron microscope (SEM). A novel situ reinforcing and toughening mechanism and model are discovered and confirmed by SEM, molecular simulation, and dynamic mechanical thermal analysis technology. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Strengthening and toughening effects of layered double hydroxide and hyperbranched polymer on epoxy resin

The effects of organically modified layered double hydroxide (O-LDH) and epoxy functionalized hyperbranched aliphatic polyester (E1), on the mechanical strength, thermal property and toughness of diglycidyl ether of bisphenol A (DGEBA) epoxy resin were studied in detail. The crystalline structure and morphology of the nanocomposites composed of DGEBA/O-LDH and DGEBA/E1/O-LDH were investigated by wide angle X-ray diffraction analysis and transmission electron microscopy observation. Both results showed that the LDH nanosheets were sufficiently exfoliated and randomly dispersed in the epoxy matrix. The thermal and mechanical properties were compared with the corresponding neat polymer matrix. The enhancement in strength and toughness was achieved by the addition of O-LDH and E1, respectively, and confirmed in terms of fracture surface analysis by scanning electron microscopy.     

Synthesis and curing kinetics of colored epoxy resin containing azo moiety

Colored epoxy resin containing azo moiety was synthesized by reaction between epichlorohydrin and bis-azodiol, which was synthesized by coupling bisphenol-A with aromatic amine. Colored epoxy resin was characterized by epoxy equivalent weight, IR spectra, Viscosity and UV visible spectroscopy. The curing of colored epoxy resin and DGEBA were characterized by differential scanning calorimetry (DSC). The thermal stability of cured products was characterized by thermogr avimetric analysis (TGA). The cured products have good thermal stability. Several glass fiber epoxy composites were fabricated and their mechanical properties, electrical properties and chemical resistance were studied.     

Preparation and Application of a New Curing Agent for Epoxy Resin

A new curing agent based on palmitoleic acid methyl ester modified amine (PAMEA) for epoxy resin was synthesized and characterized. Diglycidyl ether of bisphenol A (DGEBA) epoxy resins cured with different content of PAMEA along with diethylenetriamine (DETA) were prepared. The mechanical properties, dynamic mechanical properties, thermal properties, and morphology were investigated. The results indicated that the PAMEA curing agent can improve the impact strength of the cured epoxy resins considerably in comparison with the DETA curing agent, while the modulus and strength of the cured resin can also be improved slightly. When the PAMEA/epoxy resin weight ratio is 30/100, the comprehensive mechanical properties of the cured epoxy resin are optimal; at the same time, the crosslinking density and glass transition temperature of the cured epoxy resin are maximal.     

Study on the Performance of Diglycidyl Ether of Bisphenol-A/Hyperbranched Aromatic Polyester Epoxy Resin (HTME) System and Their Toughness Mechanism

This paper reports on the use of liquid hyperbranched aromatic polyester epoxy resin (HTME) as an additive to an epoxy resin/amine system. Four kinds of different molecular weight and epoxy equivalent weight HTME as modifiers in the diglycidyl ether of bisphenol-A (DGEBA) amine systems are discussed in detail. It was shown that the content and molecular weight of HTME have important effect on the performance of the cured system, and the performance of the HTME/DGEBA blends has maximum with the increase of content and molecular weight or generation of HTME. The impact strength and fracture toughness of the cured system with 9 wt.% second or three generation of HTME are almost 2.77 and 1.71 times, respectively, DGEBA performance; furthermore, the tensile and flexural strength can be enhanced about 17% and 20%, respectively. The glass transition temperature and Vicat temperature, however, are found to decrease to some extent. The scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), and molecular simulation technology are used to study the situ reinforcing and toughening mechanism. The three-dimensional size and structure shape of HTME-2 are displayed by molecular simulation technology.     

Hyperbranched polysiloxane‐based diglycidyl ether of bisphenol a epoxy composite for low k dielectric application

A new type of diglycidyl ether of bisphenol A (DGEBA) epoxy‐based hybrids has been developed by the incorporation of varying percentages of glycidyl‐terminated hyperbranched polysiloxane (HPSiE) into DGEBA resin and are characterized for their physicochemical, thermal, mechanical, and dielectric behaviors by modern analytical techniques. Data resulted from different studies indicate that the incorporation of HPSiE into DGEBA epoxy resin significantly improved the impact strength, thermal, and dielectric properties with an increase in the HPSiE loading. The contact angle [water and diiodomethane (DI)] increase with increases according to the weight percentages of HPSiE, which indicates the HPSiE‐modified DGEBA shows hydrophobic in nature. The resulting epoxy‐based hybrid composites can be used effectively for different industrial and engineering applications for better performance with improved longevity. POLYM. COMPOS., 34:904–911, 2013. © 2013 Society of Plastics Engineers     

Modification of novel bio‐based resin‐epoxidized soybean oil by conventional epoxy resin

Conventional epoxy resin (DGEBA), in varying proportion, was used to modify epoxidized soybean oil (ESO) based systems, crosslinked by phthalic anhydride. The properties of DGEBA modified ESO systems were investigated by dynamic mechanical analysis, impact testing, tensile and flexural testing, scanning electron microscopy, and thermogravimetric analysis. Single loss factor tan δ peak was obtained for all of the modified systems. The results show the improvement in mechanical properties from their high crosslinking densities through the introduction of DGEBA with increase in initial degradation temperature, as obtained from thermogravimetric analysis. Results approaches to an ideal composition which gives the optimum property. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

香草醇基环氧树脂的合成、固化动力学及性能

以可再生香草醇为原料,合成了一种生物基环氧树脂（DGEVA）。通过使用甲基六氢苯酐（MeHHPA）作为固化剂,制备了一种新型的生物基环氧树脂交联网络（DGEVA/MeHHPA）。对其非等温固化动力学、热性能、热机械性能、机械性能和微观形貌结构进行了系统的研究,并用商用的石油基双酚A型环氧树脂组成的石油基环氧树脂体系（DGEBA/MeHHPA）进行对比。结果表明：DGEVA/MeHHPA和DGEBA/MeHHPA具有相似的固化反应活性。DGEVA/MeHHPA具有可以与DGEBA/MeHHPA相媲美的综合性能：玻璃化转变温度为82.2℃;拉伸强度和拉伸模量分别是 (66.7±6)MPa和 (2.8±0.1)GPa;T_d5%、T_d10%和T_dmax分别是242.4℃、284.9℃和392.4℃。此外,DGEVA/MeHHPA在形变过程中发生了塑性变形而吸收了更多的断裂能。DGEVA刚性骨架和低分子量带来的潜在高交联密度赋予了DGEVA优异性能,具有在实际应用中替代石油基环氧树脂的应用潜力。     

Curing kinetics and properties of epoxy resin-fluorenyl diamine systems

Diglycidyl ether of bisphenol fluorene (DGEBF), 9,9-bis-(4-aminophenyl)-fluorene (BPF) and 9,9-bis-(3-methyl-4-aminophenyl)-fluorene (BMAPF) were synthesized to introduce more aromatic structures into the epoxy systems, and their chemical structures were characterized with FTIR, NMR and MS analyses. The curing kinetics of fluorenyl diamines with different epoxy resins including DGEBF, cycloaliphatic epoxy resin (TDE-85) and diglycidyl ether of bisphenol A (DGEBA) was investigated using non-isothermal differential scanning calorimetry (DSC), and determined by Kissinger, Ozawa and Crane methods. The thermal properties of obtained polymers were evaluated with dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The results show that the values of activation energy (E_a) are strongly dependent on the structures of epoxy resin and curing agent. The curing reactivity of epoxy system is restrained by the introduction of rigid fluorene into chain backbone and flexible methyl into side groups. The cured DGEBF/fluorenyl diamine systems exhibit remarkably higher glass transition temperature, better thermal stability and lower moisture absorption compared to those of DGEBA/fluorenyl diamine systems, and display approximate heat resistance and much better moisture resistance relative to those of TDE-85/fluorenyl diamine systems.     

Synthesis of polysiloxane‐type multifunctional flame retardant and its application in epoxy systems

Polymethyl(3‐glycidyloxypropyl)siloxane (PMGS) was synthesized as a flame‐retardant additive, which were cocured with diglycidyl ether of bisphenol‐A (DGEBA) using 4,4′‐diaminodiphenylsulfone as a curing agent. The structure of PMGS was confirmed through Fourier transform infrared and ¹H‐NMR spectra. The cured products were characterized with dynamic mechanical thermal analysis, thermogravimetric analysis, and oxygen index analyzer. With PMGS incorporated, the cured epoxy resin showed better thermal stability, higher limited oxygen index, and higher char yield. At moderate loading of PMGS, the storage modulus and glass transition temperature of the cured epoxy resin based on neat DGEBA were obviously improved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

High performance modification of hyperbranched polyborate on diglycidyl ether of bisphenol‐a resin

High performance epoxy resin was obtained by introducing hyperbranched polyborate (HBPB) into diglycidyl ether of bisphenol A (DGEBA) resin to overcome the defects such as low char yield and poor toughness of DGEBA resin. By virtue of the massive functional end groups, hyperbranched and rigid boron‐containing structures of HBPB, the thermal resistance of DGEBA resin cured with diamino diphenyl sulfone (DDS) can be greatly improved. Moreover, with the toughening effect of hyperbranched structures of HBPB, the mechanical properties such as flexural strength and interlaminar shear strength of the carbon fiber reinforced DGEBA‐DDS composite could be greatly increased by HBPB without a decrease on modulus and glass transition temperature of DGEBA‐DDS resin. POLYM. COMPOS. 36:424–432, 2015. © 2014 Society of Plastics Engineers     

Preparation of a light color cardanol-based curing agent and epoxy resin composite: Cure-induced phase separation and its effect on properties

A light color cardanol-based epoxy curing agent (MBCBE) was synthesized from cardanol butyl ether, formaldehyde and diethylenetriamine. In comparison, a phenalkamine with a similar structure was also prepared. The chemical structures were confirmed by GC–MS and FTIR. The cure behaviors of diglycidyl ether of bisphenol A (DGEBA) with these two curing agents was studied by differential scanning calorimetry (DSC). The morphology, mechanical properties, thermal properties of the cured epoxies were also investigated. The DSC results indicated that MBCBE is less reactive than the phenalkamine. The morphology of the cured MBCBE/DGEBA consisted of cavities dispersed within a continuous epoxy matrix. The cavities markedly improved the lap shear strength and impact strength of the cured resin. Both the two cured resins indicated a two-stage decomposition mechanism. Compared with PKA/DGEBA, the weight loss of MBCBE/DGEBA at the first stage was mainly resulted from the dispersed phase in the epoxy matrix.     

Mechanical and dynamic mechanical properties of jute fibers–Novolac–epoxy composite laminates

A study was done of jute composite using a polymer matrix of epoxidized Novolac resin (ENR), diglycidyl ether of bisphenol A (DGEBA)–based epoxy, and their blends with different weight percentages of the resins. It was found that on blending ENR with DGEBA, the storage modulii at room temperature are enhanced by about 100% or more in the case of 30 and 40% ENR‐containing matrices, whereas the enhancement in the case of 20 and 12% ENR‐containing matrices is only 50% that of the pure matrix. It was also observed that the tan δ peak heights of the composites containing 30 and 40% ENR are closer to that of 20% ENR‐containing composite. The probable explanation drawn on the basis of experimental findings of DMA and mechanical analysis is that by blending ENR with DGEBA epoxy it is possible to manufacture jute composites with increased stiffness without sacrificing their ductility. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2800–2807, 2002     

核壳聚合物粒子对环氧树脂热膨胀系数的影响

采用核壳聚合物(Core-Shell Polymer,CSP)粒子改性环氧树脂,通过红外光谱、热力学分析和扫描电镜研究了CSP粒子对环氧树脂基体热膨胀系数(CTE)的影响。结果表明:CSP粒子壳材料分子链中的羰基在环氧树脂固化过程中可与环氧分子侧链上的羟基形成氢键作用,从而加强了核壳聚合物粒子与环氧树脂的界面作用。随着CSP粒子质量分数的增加,改性环氧树脂基体的玻璃化转变温度呈下降趋势;相对于纯环氧树脂,改性环氧树脂在玻璃化转变温度下的CTE呈现先下降后上升的趋势,添加质量分数为0.5%的CSP后,其CTE值降低了12.88%。但在玻璃化转变温度上的热膨胀系数均高于纯环氧树脂。     

Study on Novel Epoxy Based Poly (Schiff Reagent)s

Abstract

Novel poly(schiff reagent)s from diketo derivative of epoxy resin were synthesised and characterised. A series of epoxy resin based poly(schiff reagent)s were synthesised by reacting an epoxy resin, diglycidyl ether of bisphenol-A (DGEBA) with 4-amino acetophenone (4-AAP) in a 1:2 mole ratio to afford the corresponding diketo derivative, and subsequent reaction with various aliphatic diamines in a presence of a triethyl amino as a catalyst. The resultant poly(schiff reagent)s were characterised by infrared spectroscopy (IR) and number average molecular weight (Mn) of PSs were estimated by non-aqueous conductometric titration. As produced, PSs having amine groups may act for curing of epoxy resins. Differential scanning calorimetric (DSC) curing kinetics of the epoxy resins viz. diglycidyl ether of bisphenol-A(DGEBA) and triglytidyl-p-amino phenol (TGPAP) have been investigated using PSs as a curing agent and triethyl amine as a catalyst. Thermal stability of the cured epoxy systems were studied by thermogravimetric analysis (TGA). The glass fiber reinforced composites of the produced PSs-epoxy system have been fabricated and were characterised by their mechanical properties and chemical resistance.     

Effects of reactive compatibilizer on the core-shell structured modifiers toughening of poly(trimethylene terephthalate)

Poly(trimethylene terephthalate)/polybutadiene grafted polymetyl methacrylate (PB-g-PMMA, MB) blends were prepared by melt processing with varying weight ratios (0-5 wt%) of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin as a reactive compatibilizer. DMA result showed PTT was partially miscible with MB particles in the presence of the compatibilizer. Fourier transform infrared (FTIR) and rheological measurements further identified the reactions between PTT and DGEBA epoxy resin. Scanning electron microscopy (SEM) displayed that the core-shell structured modifiers exhibit a smaller dispersed domain size with the addition of DGEBA epoxy resin. Mechanical tests showed the impact and tensile properties of PTT blends are improved by the introduction of DGEBA epoxy resin to the blends. SEM and TEM results showed shear yielding of PTT matrix and cavitation of rubber particles were the major toughening mechanisms.     

Synthesis and properties of epoxy resin modified with epoxy-terminated liquid polybutadiene

Epoxy resin networks have been modified with block copolymer of polybutadiene and bisphenol A diglycidyl ether (DGEBA)-based epoxy resin. Block copolymers prepared from isocyanate-terminated polybutadiene (NCOPBER) resulted in cured transparent epoxy networks with no discernible phase-separated morphology, as indicated by scanning electron microscopy. Epoxy resin modified with block copolymer derived from carboxyl-terminated polybutadiene (CPBER) presented an opaque aspect with dispersed rubber particle diameters in the range of 0.5-3μm. This value is substantially smaller than that found in epoxy matrix modified with hydroxyl-terminated polybutadiene. The different morphological characteristics observed in these modified systems were attributed to the different times to achieve the gelation (gel time) and also to the different structures of the block copolymers. The visual homogeneity of the NCOPBER block copolymer-modified network cannot be attributed to the presence of dissolved rubber, since the glass transition temperature of the epoxy matrix (determined from dynamic mechanical analysis) has not been substantially influenced by the presence of this block copolymer. The epoxy resin modified with the different block copolymers presented an improved impact resistance. The best mechanical performance in terms of flexural and tensile properties was achieved with the block copolymer derived from carboxyl-terminated polybutadiene, whereas a more flexible material has been obtained with NCOPBER block copolymer-modified network.     

Modified Cyclohexanone-Formaldehyde Resin as an Epoxy Resin Curing Agent

Cyclohexanone-formaldehyde (CHF) resin was brominated and the brominated CHF (BCHF) was then reacted with excess aromatic diamines. The aminated CHF resins designated as ACHFs (modified ketone resin) were characterized and then applied as epoxy resin curing agents. Thus, the curing of the commercial epoxy resin diglycidil ether of bisphenol-A (DGEBA) by ACHFs was monitored by differential scanning calorimetric (DSC), based on the the DSC scans, the glass fiber-reinforced composites of DGEBA-ACHF systems were prepared and characterized by chemical resistivity and mechanical properties.