Cure behavior,morphology, and mechanical properties of the melt blends of epoxy with polyphenylene oxide

Cure behavior, miscibility, and phase separation have been studied in blends of polyphenylene oxide (PPO) with diglycidyl ether of bisphenol A (DGEBA) resin and cyanate ester hardener. An autocatalytic mechanism was observed for the epoxy/PPO blends and the neat epoxy. It was also found that the epoxy/PPO blends react faster than the neat epoxy. During cure, the epoxy resin is polymerized, and the reaction‐induced phase separation is accompanied by phase inversion upon the concentration of PPO greater than 50 phr. The dynamic mechanical measurements indicate that the two‐phase character and partial mixing existed in all the mixtures. However, the two‐phase particulate morphology was not uniform especially at a low PPO content. In order to improve the uniformity and miscibility, triallylisocyanurate (TAIC) was evaluated as an in situ compatibilizer for epoxy/PPO blends. TAIC is miscible in epoxy, and the PPO chains are bound to TAIC network. SEM observations show that adding TAIC improves the miscibility and solvent resistance of the epoxy/PPO blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 26–34, 2000     

Modification of epoxy resins by the addition of PVC plastisols

An epoxy resin based on bisphenol A has been modified by the addition of different amounts of a plastisol, based on poly(vinyl chloride) (PVC) and diethylhexyl phthalate (DOP). The fluid state of those materials makes their blending easier. After a curing process, some different materials, with properties ranging from the rigidity of a thermosetting resin to the flexibility of a plastisol, can be obtained. The variation of different parameters, such as tensile strength, Young's modulus, dielectric constant, and others, with the concentration of plastisol, has been studied. Some materials with properties similar to common thermoplastics (PP, ABS, or SB) can be processed, depending on the epoxy-to-plastisol ratio. The obtained results enable us the use of those materials in prototyping and other industrial processes. The obtained prototypes should have a similar mechanical behavior to thermoplastics. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1769–1777, 1998     

PPO/EP混合物耐热性和相分离的研究

利用差示扫描量热仪研究了聚苯醚／环氧树脂（PPO／EP）混合物的耐热性。结果表明，随着PPO含量的增加其耐热性提高,在PPO／EP混合物中加入苯乙烯-马来酸酐共聚物可有效地提高混合物的耐热性。用扫描电镜观察了PPO／EP混合物的相分离过程。结果表明,PPO和EP混合物的相分离是通过旋节线分离发生的，且PPO和EP之间缺乏明显的交联。     

Thermal properties and fire behaviour of materials produced from curing mixed epoxy and phenolic resins

Thermal stability and fire behaviour of materials obtained from curing mixed epoxy and phenolic resins have been studied, the decomposition processes being compared with those for the pure resins. Samples were cured by triethylenetetramine or p‐toluenesulphonic acid by isothermal pressing at 90^°C, and decompositions were carried out under nitrogen and air environment from 50 to 1000^°C. Only for mixtures with higher proportion of epoxy resin, the decomposition process goes through a unique step as for the pure resin. Results from fire tests indicated that mixtures are classified as M3 and F1. Copyright © 2008 John Wiley & Sons, Ltd.     

Cure kinetics of ternary blends of epoxy resins studied by nonisothermal DSC data

The curing kinetics of blends of diglycidyl ether of bisphenol A (DGEBA), cycloaliphatic epoxy resins, and carboxyl‐terminated butadiene‐acrylonitrile random copolymer (CTBN) in presence of 4,4′‐diamino diphenyl sulfone (DDS) as the curing agent was studied by nonisothermal differential scanning calorimetry (DSC) technique at different heating rates. The kinetic parameters of the curing process were determined by isoconversional method given by Malek for the kinetic analysis of the data obtained by the thermal treatment. A two‐parameter (m, n) autocatalytic model (Sestak‐Berggren equation) was found to be the most adequate selected to describe the cure kinetics of the studied epoxy resins. The values of E_a were found to be 88.6 kJ mol^?1 and 61.6 kJ mol^?1, respectively, for the studied two sample series. Nonisothermal DSC curves obtained using the experimental data show a good agreement with that theoretically calculated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Thermal and mechanical properties of epoxy composites reinforced by a natural hydrophobic sand

If a low weight percentage of crude fine fillers can improve properties of polymer materials directly without complicated chemical treatment process involved, it will be significant for many industrial applications. Our previous study indicated that a kind of Cancun natural sand could be an effective filler material for polymer composites. In this current work, the epoxy composites reinforced by this kind of natural sand particles were prepared and thermal and mechanical properties of the composites containing up to 5 wt % of the sand particles were characterized. Results showed that the highest flexural strength appears in the epoxy composite containing 1 wt % sand particles. A damage model was used to interpret the flexural properties, which showed an acceptable agreement with the experimental results. The glass transition temperature, high temperature storage modulus, and dimensional stability of the sand/epoxy composites monotonically increased with the addition of the sand particles. The sand particle/epoxy composites also displayed a noticeable enhancement in thermal conductivity. Theoretical analysis showed that in addition to conduction, other heat transport mechanisms played roles in the improved heat transmission through the composites. As a natural porous micron-scale material, Cancun sand has the potential for applications in cost-effective composites with enhanced mechanical and thermal properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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。     

Mechanical and morphological properties of epoxy resins modified by poly(phthalazinone ether sulfone ketone)

A series of blends have been prepared by adding a novel thermoplastic poly(phthalazinone ether sulfone ketone) (PPESK) in varying proportions to diglycidyl ether of bisphenol A epoxy resin (DGEBA) cured with p‐diaminodiphenylsulfone (DDS). All the blends showed two‐phase structures characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Addition of the PPESK resulted in great enhancement of glass transition temperatures (T_g) both in the epoxy‐rich phase and in the PPESK‐rich phase by reason of the special structure of PPESK. There was moderate increase in the fracture toughness as estimated by impact strength. Fracture mechanisms such as crack deflection and branches, ductile microcracks, ductile tearing of the thermoplastic, and local plastic deformation of the matrix were responsible for the increase in the fracture toughness of the blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

脂环族环氧树脂／双酚A环氧树脂共混改性研究

采用脂环族环氧树脂（EPL-4221）与双酚A型环氧树脂E-51共混,用酸酐固化剂和促进剂使其固化,研究脂环族环氧树脂的用量对共混树脂性能的影响及其规律性,包括冲击强度、弯曲强度、拉伸强度、维卡软化点温度、漆膜的粘附力、铅笔硬度、耐磨性以及拉伸剪切强度。结果表明,随脂环族环氧树脂用量的增加,共混树脂的综合性能先增加后降低,脂环族环氧树脂的质量分数为15％-20％时,具有最大值。     

Incorporation of hyperbranched polyamide‐functionalized graphene oxide into epoxy for improving interfacial and mechanical properties

The incorporation of hyperbranched polyamide‐functionalized graphene oxide (HPA‐GO) into epoxy was proposed to improve the interfacial and mechanical properties. Benefiting from improved dispersion and strengthened interfacial interaction, epoxy composites with HPA‐GO showed significant improvements in mechanical and thermomechanical properties at low GO loading. The interaction at the HPA‐GO/epoxy interface was investigated to confirm the occurrence of chemical bonding. Strong interfacial bonding improved the stress transfer and distribution of HPA‐GO/epoxy interface. Accordingly, the overall strength of epoxy composites was effectively improved on account of the uniform dispersion of HPA‐GO and interfacial chemical interaction between HPA‐GO and epoxy. Compared with neat epoxy resin, the inclusion of 0.10 wt% HPA‐GO led to 310.5 and 37.2% increase in impact strength and tensile strength, respectively. © 2019 Society of Chemical Industry     

Miscibility and mechanical properties of tetrafunctional epoxy resin/phenolphthalein poly(ether ether ketone) blends

Phenolphthalein poly(ether ether ketone) (PEK‐C) was found to be miscible with uncured tetraglycidyl 4,4′‐diaminodiphenylmethane (TGDDM), which is a type of tetrafunctional epoxy resin (ER), as shown by the existence of a single glass transition temperature (T_g) within the whole composition range. The miscibility between PEK‐C and TGDDM is considered to be due mainly to entropy contribution. Furthermore, blends of PEK‐C and TGDDM cured with 4,4′‐diaminodiphenylmethane (DDM) were studied using dynamic mechanical analysis (DMA), Fourier‐transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). DMA studies show that the DDM‐cured TGDDM/PEK‐C blends have only one T_g. SEM observation also confirmed that the blends were homogeneous. FTIR studies showed that the curing reaction is incomplete due to the high viscosity of PEK‐C. As the PEK‐C content increased, the tensile properties of the blends decreased slightly and the fracture toughness factor also showed a slight decreasing tendency, presumably due to the reduced crosslink density of the epoxy network. SEM observation of the fracture surfaces of fracture toughness test specimens showed the brittle nature of the fracture for the pure ER and its blends with PEK‐C. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 598–607, 2001     

Thermal and mechanical properties of poly(butylene terephthalate)/epoxy blends

In this study, melt blends of poly(butylene terephthalate) (PBT) with epoxy resin were characterized by dynamic mechanical analysis, differential scanning calorimetry, tensile testing, Fourier transform infrared spectroscopy, and wide‐angle X‐ray diffraction. The results indicate that the presence of epoxy resin influenced either the mechanical properties of the PBT/epoxy blends or the crystallization of PBT. The epoxy resin was completely miscible with the PBT matrix. This was beneficial to the improvement of the impact performance of the PBT/epoxy blends. The modification of the PBT/epoxy blends were achieved at epoxy resin contents from 1 to 7%. The maximum increase of the notched Izod impact strength (≈ 20%) of the PBT/epoxy blends was obtained at 1 wt % epoxy resin content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Ionic liquid modified graphene oxide for enhanced flame retardancy and mechanical properties of epoxy resin

In this work, to improve its dispersion and flame retardancy, graphene oxide (GO) was functionalized by silane coupling agent KH550 and 1-butyl-3-methylimidazole hexafluorophosphate (PF₆-ILs), and characteristics of the PF₆-ILs@GO was obtained by transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Then, the synergistic flame retardant of GO or PF₆-ILs@GO and melamine pyrophosphate (MPP) were applied for epoxy resin (EP) materials. Specifically, the limiting oxygen index (LOI) value of EP with 0.1 wt% PF₆-ILs@GO was increased to 29.2% from 27.5% of EP/MPP composites, and the UL-94 test reached the V-0 rating. The CCT results showed that the total heat release (THR) and total smoke release (TSP) of EP/MPP/PF₆-ILs@GO composites were significantly 24.4% and 53.4% lower than that of EP/MPP composites. Besides, the thermal behavior investigated by TGA indicated that the char-forming effect of GO and PF₆-ILs@GO was great, the residual char of EP/MPP/PF₆-ILs@GO composites was as high as 19.5% at 700°C, and its thermal stability was higher than that of EP/MPP composites. On the other hand, the tensile strength of EP/MPP/GO and EP/MPP/PF₆-ILs@GO composites were increased by 15.6% and 28.3% compared with EP/MPP composites. According to SEM analysis, the EP/MPP/GO composites formed a good protective char layer, which can effectively improve flame retardancy of EP. This research represents a new method of flame retardant modified GO to improve the flame retardancy and mechanical properties of polymers.     

Influence of cyanate content on the morphology and properties of epoxy resins with phenolphthalein poly(ether ketone)

Phenolphthalein poly(ether ketone) (PEK‐C) was blended with the diglycidyl ether of bisphenol A epoxy resin and bisphenol A dicyanate ester. The effect of cyanate content on cure behaviors, thermal and mechanical properties of PEK‐C/epoxy/cyanate mixtures was investigated. As results, the increase of cyanate content slightly hindered the cure reaction of the mixtures. Fourier transform infrared results indicated that the curing reaction of the cured mixtures was complete. When the cyanate ester content increased, the flexural properties and T_g values were enhanced, and the initial thermal decomposition temperature was reduced. A significant improvement in fracture toughness was obtained when the cyanate group in the mixtures was excessive. The fracture toughness can be well explained by SEM observations. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal and mechanical characterization of epoxy resins toughened using preformed particles

Preformed, multilayer particles have been used to toughen an epoxy resin. The particles were formed by emulsion polymerization and consist of alternate glassy and rubbery layers, the outer layer having glycidyl groups to give the possibility of chemical bonding of the particles in the cured resin. Two variants of this type of particle were used, termed GM(47/15) and GM(47/37); both types have an overall diameter of 0.5 µm, but the former have a thicker rubbery layer. For comparison, acrylic toughening particles (ATP) with no surface functionality and a liquid carboxyl‐terminated butadiene–acrylonitrile (CTBN) rubber were used as toughening agents. The epoxy resin system consisted of a commercial diglycidyl ether of bisphenol A (Shell Epon 828) with diamino‐3,5‐diethyl toluene as hardener, two commercial sources of which were used, namely Ethacure‐100 (Albemarle SA) and DX6509 (Shell Chemicals). These hardeners contain a mixture of two isomers, namely 2,6‐diamino‐3,5‐diethyltoluene and 2,4‐diamino‐3,5‐diethyltoluene Thermogravimetry in nitrogen shows that the preformed toughening particles begin to degrade at 230 °C, whereas the cured resin begins to degrade rapidly at 350 °C. Thus, even though the particles are less thermally stable than the cured resin, their degradation temperature is well above the glass transition temperature of the resin, and their use does not affect the thermal stability of the toughened materials at normal use temperatures. The performance of the toughening agents was compared using Ethacure‐100 as the hardener. The GM(47/15) and GM(47/37) toughening particles gave rise to a greater toughening effect than the ATP and the CTBN. For example, the fracture energies were: 0.26 kJ m^?2 for the unmodified resin; 0.60 kJ m^?2 for the resin toughened with CTBN; and 0.69 kJ m^?2 for the resin toughened with the GM(47/15) particles. The ultimate tensile stress of the unmodified epoxy resin was 43 MPa, which increased to 55 MPa when 20 wt% of GM(47/15) toughening particles were added. The toughness of resins cured with the DX6509 hardener were superior to those obtained with the Ethacure‐100 hardener, most probably due to DX6509 producing a less‐highly‐crosslinked network. This highlights the sensitivity of the toughening process to the hardener used, even for hardeners of a similar nature. © 2001 Society of Chemical Industry     

Synthesis and thermal properties of combined liquid crystalline epoxy resins

Liquid crystalline epoxy resins were prepared by the curing reaction of epoxy and amine compounds with a mesogenic group in the mesomorphic temperature range. Some epoxy resins exhibited a typical liquid crystalline phase. Curing reaction of a mesogenic epoxy compound with an aliphatic amine compound containing cyano biphenyl group was faster than that of another epoxy resins confirmed by thermally controlled Fourier transform infrared measurements. The glass transition temperature of the liquid crystalline epoxy resin containing cyano biphenyl group increased with increasing curing reaction time. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1979–1990, 1998     

Study on epoxy resins modified by polycarbonate polyurethanes

In this article, the structure and properties of the epoxy resin (EP) modified by polyurethane (PU) prepolymers were studied. The three types of polyurethane prepolymers, namely, polycarbonate-type PU (TPC), polyether-type PU, and polycarbonate–polyether-type PU were employed. The samples were analyzed by means of an infrared spectrometer, a differential scanning calorimeter, a scanning electron microscope, a transmission electron microscope, a scanning tunnel microscope, and a thermal gravimeter. The results show that the EP modified by TPC is of excellent thermal resistance and mechanical properties. Specifically, when the ratio of PU to EP is 10/100 (wt/wt), optimal properties are achieved. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 887–893, 1998     

The effect of urea bond on structure and properties of toughened epoxy resins

In this article, modified poly(oxypropylene) diamines were synthesized and used as a new flexible curing agent for epoxy resins. The purpose of modification is to introduce urea group into epoxy resins. The reaction rate, mechanical properties, glass transition temperature (T_g), and fracture surface morphology of these toughened epoxy resins were investigated. Because of urea groups, the reactivity between poly(oxypropylene) diamines and epoxy resins was significantly enhanced. At the same time, the urea groups resulted in strong intersegmental hydrogen bonding between modified poly(oxypropylene) chain, which reduced the compatibility of poly(oxypropylene) with epoxy resins and resulted in higher T_g of toughened epoxy. The modified sample had tensile strength of 15.8 MPa and ultimate elongation of 118% at room temperature, whereas the unmodified sample only had 6.2 MPa and 70%. The scanning electron microscope analysis showed that the modified system displayed tough fracture feature, whereas the unmodified system showed typical brittle fracture. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

新型含磷环氧树脂的研究进展

有机和无机磷化物是新一代无卤、环保和绿色新型阻燃改性单体,可合成具有优异热稳定性、阻燃特性和物理机械性能的新型含磷环氧树脂。综述了DOPO的结构性能和化学反应性,以及以DOPO和氧氯化磷为原料合成新型含磷中间体和环氧树脂的结构、合成方法及性能等。     

液体聚硫聚脲增韧环氧树脂胶粘剂的合成与力学性能

利用异佛尔酮异氰酸酯扩链液体聚硫橡胶，合成了不同硬段含量的液体聚硫聚脲齐聚物，表征了该齐聚物增韧环氧树脂前后巯基含量、环氧含量、粘度及玻璃化温度等变化，并用来增韧环氧树脂-聚酰胺固化体系，研究了增韧环氧树脂的应力应变和粘合强度变化。