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1.
A new epoxy resin (Bis-ENA) containing naphthalene structure linked with a 1,4-bis(isopropylidene)phenylene was synthesized and was confirmed by elemental analysis, infrared spectroscopy, and 1H nuclear magnetic resonance spectroscopy. To estimate the effect of naphthalene moiety on the cured polymer, an epoxy resin (Bis-EP) having phenyl moiety was synthesized, and curing behaviors of Bis-ENA and Bis-EP with phenol novolac were evaluated by differential scanning calorimetry. The incorporation of naphthalene structure into the resin backbone increased the curing temperature and reduced the curing reactivity. Thermal properties of the cured polymers obtained from Bis-ENA and Bis-EP with phenol novolac were examined by thermomechanical analysis and dynamic mechanical analysis. Mechanical properties and moisture resistance were evaluated by flexural strength, flexural modulus, and moisture absorption measurements. The cured polymer obtained from Bis-ENA showed higher glass transition temperature, higher flexural modulus, lower thermal expansion, and lower moisture absorption than that from Bis-EP. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3063–3069, 1999  相似文献   

2.
A novel flame‐retardant epoxy resin, (4‐diethoxyphosphoryloxyphenoxy)(4‐glycidoxyphenoxy)cyclotriphosphazene (PPCTP), was prepared by the reaction of epichlorohydrin with (4‐diethoxyphosphoryloxyphenoxy)(4‐hydroxyphenoxy)cyclotriphosphazene and was characterized by Fourier transform infrared, 31P NMR, and 1H NMR analyses. The epoxy resin was further cured with diamine curing agents, 4,4′‐diaminodiphenylmethane (DDM), 4,4′‐diaminodiphenylsulfone (DDS), dicyanodiamide (DICY), and 3,4′‐oxydianiline (ODA), to obtain the corresponding epoxy polymers. The curing reactions of the PPCTP resin with the diamines were studied by differential scanning calorimetry. The reactivities of the four curing agents toward PPCTP were in the following order: DDM > ODA > DICY > DDS. In addition, the thermal properties of the cured epoxy polymers were studied by thermogravimetric analysis, and the flame retardancies were estimated by measurement of the limiting oxygen index (LOI). Compared to a corresponding Epon 828‐based epoxy polymer, the PPCTP‐based epoxy polymers showed lower weight‐loss temperatures, higher char yields, and higher LOI values, indicating that the epoxy resin prepared could be useful as a flame retardant. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 972–981, 2000  相似文献   

3.
Nonaqueous synthesis of nanosilica in diglycidyl ether of bisphenol‐A epoxy (DGEBA) resin has been successfully achieved in this study by reacting tetraethoxysilane (TEOS) directly with DGEBA epoxy matrix, at 80 °C for 4 h under the catalysis of boron trifluoride monoethylamine (BF3MEA). BF3MEA was proved to be an effective catalyst for the formation of nanosilica in DGEBA epoxy under thermal heating process. FTIR and 29Si NMR spectra have been used to characterize the structures of nanosilica obtained from this direct thermal synthetic process. The morphology of the nanosilica synthesized in epoxy matrix has also been analyzed by TEM and SEM studies. The effects of both the concentration of BF3MEA catalyst and amount of TEOS on the diameters of nanosilica in the DGEBA epoxy resin have been discussed in this study. From the DSC analysis, it was found that the nanosilica containing epoxy exhibited the same curing profile as pure epoxy resin, during the curing reaction with 4,4′‐diaminodiphenysulfone (DDS). The thermal‐cured epoxy–nanosilica composites from 40% of TEOS exhibited high glass transition temperature of 221 °C, which was almost 50 °C higher than that of pure DGEBA–DDS–BF3MEA‐cured resin network. Almost 60 °C increase in thermal degradation temperature has been observed during the TGA of the DDS‐cured epoxy–nanosilica composites containing 40% of TEOS. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 757–768, 2006  相似文献   

4.
A new type of epoxy resin which contained cyclic phosphine oxide group in the main chain was synthesized. The structure of the new type of epoxy resin was confirmed by elemental analyses (EA), infrared spectroscopy (IR), and 1H-NMR and 13C-NMR spectroscopies. In addition, compositions of the new synthesized cyclic phosphine oxide epoxy resin (EPCAO) with three curing agents, e.g., bis(3-aminophenyl)methylphosphine oxide (BAMP), 4,4′-diamino-diphenylmethane (DDM), and 4,4′-diaminodiphenylsulfone (DDS), were used for making a comparison of its curing reactivity, heat, and flame retardancy with that of Epon828 and DEN438. The reactivities were measured by differential scanning calorimetry (DSC). Through the evaluation of thermal gravimetric analysis (TGA), those polymers which were obtained through the curing reactions between the new epoxy resin and three curing agents (BAMP, DDM, DDS) also demonstrated excellent thermal properties as well as a high char yield. © 1996 John Wiley & Sons, Inc.  相似文献   

5.
Phenyl bisthioureas: 4,4′-(bisthiourea)diphenylmethane (DTM), 4,4′-(bisthiourea)diphenyl ether (DTE), and 4,4′-(bisthiourea)diphenyl sulfone (DTS) were synthesized and used as curing agents for the epoxy resin diglydicyl ether bisphenol A (DGEBA). Synthesized phenyl bisthioureas were characterized using FT-IR and 1H-NMR analysis. For comparison studies the epoxy system was also cured using the conventional aromatic amine 4,4′-diaminodiphenyl ether (DDE). Curing kinetics of epoxy/amine system was studied by dynamic and isothermal differential scanning calorimeter (DSC). Curing kinetic was evaluated based on model-free kinetics (MFK) and ASTM E 698 model, and the activation energy was compared with DDE. Curing system of phenyl bisthiourea link (DGEBA/DTM, DGEBA/DTE, and DGEBA/DTS) shows two exothermic peaks, while that of the conventional aromatic amines showed only a single peak. The initial exothermic peak is due to the primary nitrogen of the thiourea group, and the exotherm at higher temperature is due to the presence of thiourea groups. Glass transition temperature (T g) of DGEBA/DTM, DGEBA/DTE, and DGEBA/DTS cured resins were lowered by 323 K when compared to the widely used diaminodiphenyl ether (DDE) cured resin. Oxidation induction temperature measurement performed on DSC suggests that the DGEBA/DTM, DGEBA/DTE, and DGEBA/DTS system cured resins has better oxidative stability when compared to cured DGEBA/DDE resin system.  相似文献   

6.
A novel liquid‐crystalline epoxy resin combining biphenyl and aromatic ester‐type mesogenic units, diglycidyl ether of 4,4′‐bis(4‐hydroxybenzoyloxy)‐3,3′,5,5′‐tetramethyl biphenyl, was synthesized. Its spectroscopic structure, thermal properties, and phase structures were investigated with NMR, differential scanning calorimetry (DSC), and polarized light microscopy (PLM), respectively. The curing agent, diaminodiphenylsulfone, was chosen to investigate the curing behavior by means of DSC and PLM during isothermal and nonisothermal processes. Only one exothermal peak appeared in the isothermal DSC curves. Birefringence was also observed during the curing processes and preserved after postcuring. Compared with short rigid‐rod and flexible epoxies, the cured liquid‐crystalline epoxy resin that was obtained displayed special thermal stability according to thermogravimetric analysis because of its long rigid‐rod mesogenic unit and bulky methyl groups. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 727–735, 2007  相似文献   

7.
A new bismaleimide (BMI) resin was synthesized to formulate epoxy(tetraglycidyl diaminodiphenyl methane; TGDDM) – bismaleimide thermoset blends for composite matrix applications. 4,4′-diaminodiphenyl methane (DDM) was used as an amine curing agent for the TGDDM. A Fourier transform infrared (FTIR) spectroscopy was employed to characterize the new BMI resin. Cure behavior of the epoxy–BMI blends was studied using a differential scanning calorimeter (DSC). DSC thermograms of the thermoset blends indicated two exothermic peaks. The glass transition temperature of the thermoset blends decreased with BMI content. Thermogravimetric analysis (TGA) was carried out to investigate thermal degradation behavior of the cured epoxy–BMI thermoset blends. The new BMI resin reacted partially with the DDM and weak intercrosslinking polymer networks were formed during cure of the thermoset blends.  相似文献   

8.
A new hyperbranched‐linear‐hyperbranched polymer was prepared in a one pot process by reaction of 4,4‐bis(4‐hydroxyphenyl)valeric acid and poly(ethylene glycol) (HPH). After characterization by 1H and 13C NMR, SEC, DSC, and TGA, this polymer was used, in proportions of 5, 10, and 15 phr, as a chemical modifier in the UV and thermal cationic curing of 3,4‐epoxycyclohexylmethyl‐3′,4′‐epoxycyclohexyl carboxylate epoxy resin. The curing process was studied by calorimetry, demonstrating the accelerating effect of the hydroxyl groups present in HPH's structure. The morphology of the resulting thermosets depended on the curing system used, as demonstrated by FE‐SEM microscopy, but in both cases phase separation occurred. Thermosets obtained by thermal curing presented lower thermal stability than UV‐cured materials. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

9.
A methodology for preparing porous epoxy monolith via chemically induced phase separation was proposed. The starting system was a mixture of an epoxy precursor, diglycidyl ether of bisphenol‐A (DGEBA), a curing agent, 4,4′‐diaminodiphenylmethane (DDM), and a thermoplastic polymer, polypropylene carbonate (PPC). As DGEBA was cured with DDM, the system became phase‐separated having PPC particles dispersed in epoxy matrix. After PPC particles were removed by thermal degradation, a porous structure was obtained. The phase separation mechanism was determined by the initial composition and illustrated by a pseudophase diagram. The pore size increased with increasing the concentration of PPC and raising the curing temperature. The intermediate and final morphologies of the system were studied using optical and scanning electron microscopy, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010  相似文献   

10.
Thermosetting blends of an aliphatic epoxy resin and a hydroxyl‐functionalized hyperbranched polymer (HBP), aliphatic hyperbranched polyester Boltorn H40, were prepared using 4,4′‐diaminodiphenylmethane (DDM) as the curing agent. The phase behavior and morphology of the DDM‐cured epoxy/HBP blends with HBP content up to 40 wt % were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The cured epoxy/HBP blends are immiscible and exhibit two separate glass transitions, as revealed by DMA. The SEM observation showed that there exist two phases in the cured blends, which is an epoxy‐rich phase and an HBP‐rich phase, which is responsible for the two separate glass transitions. The phase morphology was observed to be dependent on the blend composition. For the blends with HBP content up to 10 wt %, discrete HBP domains are dispersed in the continuous cured epoxy matrix, whereas the cured blend with 40 wt % HBP exhibits a combined morphology of connected globules and bicontinuous phase structure. Porous epoxy thermosets with continuous open structures on the order of 100–300 nm were formed after the HBP‐rich phase was extracted with solvent from the cured blend with 40 wt % HBP. The DSC study showed that the curing rate is not obviously affected in the epoxy/HBP blends with HBP content up to 40 wt %. The activation energy values obtained are not remarkably changed in the blends; the addition of HBP to epoxy resin thus does not change the mechanism of cure reaction of epoxy resin with DDM. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 889–899, 2006  相似文献   

11.
Novel phosphorus-containing epoxy resins (1–3% phosphorus content) were synthesized by the reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) and the diglycidyl ether of bisphenol A and then cured with 4,4′-diaminodiphenyl sulfone or phenol novolac. Differential scanning calorimetry, high performance liquid chromatography, and epoxide equivalent weight titration were used to trace the reaction between the DOPO and the epoxy. The thermal stability and flame retardancy were checked by thermal gravimetric analysis, the limiting oxygen index, and the UL-94 vertical test. The glass transitions were measured by dynamic mechanical analysis. The relation between these properties (thermal stability, flame retardancy, and glass transition) and the DOPO contents (phosphorus content) were discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3903–3909, 1999  相似文献   

12.
A novel tri-functional cycloaliphatic epoxy resin was synthesized starting from dicyclopentadiene. The chemical structures of the resultant epoxy resin and its precursor were characterized with FTIR spectroscopy, EEW, 1H NMR and Mass spectrographic analyses. The thermal and mechanical properties of the resulting polymer were evaluated with differential scanning calorimeter (DSC), thermo-gravimetric and thermal mechanical analysis. Compared to that of the common cycloaliphatic epoxy resin ERL-4221, the cured polymer of the novel epoxy resin exhibited lower thermal degradation temperature with much higher char yield and similar thermal expansion coefficient. These excellent overall performances make it a promising packaging material.  相似文献   

13.
Blends of a tetrafunctional epoxy resin, tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM), and a hydroxyl‐functionalized hyperbranched polymer (HBP), aliphatic hyperbranched polyester Boltorn H40, were prepared using 3,3′‐diaminodiphenyl sulfone (DDS) as curing agent. The phase behavior and morphology of the DDS‐cured epoxy/HBP blends with HBP content up to 30 phr were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The phase behavior and morphology of the DDS‐cured epoxy/HBP blends were observed to be dependent on the blend composition. Blends with HBP content from 10 to 30 phr, show a particulate morphology where discrete HBP‐rich particles are dispersed in the continuous cured epoxy‐rich matrix. The cured blends with 15 and 20 phr exhibit a bimodal particle size distribution whereas the cured blend with 30 phr HBP demonstrates a monomodal particle size distribution. Mechanical measurements show that at a concentration range of 0–30 phr addition, the HBP is able to almost double the fracture toughness of the unmodified TGDDM epoxy resin. FTIR displays the formation of hydrogen bonding between the epoxy network and the HBP modifier. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 417–424, 2010  相似文献   

14.
Abstract

A novel cyclotriphosphazene-based epoxy monomer, hexa-[4-(glycidyloxycarbonyl) phenoxy]cyclotriphosphazene (HGCP), was synthesized via a four-step synthetic route, and fully characterized by 1H, 13C, and 31P NMR spectroscopy, high-resolution mass spectrometry, and elemental analysis. Thermosetting systems based on HGCP with three curing agents, for example, 4,4′-diaminodiphenylsulfone (DDS), 4,4′-diaminodiphenylmethane (DDM), and dicyandiamide (DICY), were used for making a comparison of their thermal curing behaviors. The curing behaviors were measured by differential scanning calorimetry. Moreover, flame retardancy of HGCP thermosetting systems was estimated by Limiting Oxygen Index (LOI) and Vertical Burning Test (UL-94). The resulting HGCP thermosetting systems exhibited better flame retardancy than the common epoxy resins diglycidyl ether of bisphenol A (DGEBA) and the regular brominated bisphenol A epoxy resin (TBBA) cured by DDS, respectively. When HGCP was cured by DDS, its thermosetting system gave the most char residues, met the UL-94 V-0 classification, and had a limiting oxygen index value greater than 35.  相似文献   

15.
The epoxy resin containing a typical mesogenic group such as biphenol was cured with catechol novolak and aromatic diamines which have neighboring active hydrogens. In the biphenol-type epoxy resin cured with catechol novolak, 4,4′ diaminodiphenylmethane, and p-phenylenediamine (PPD), the glass-rubber transition almost disappeared, and thus a very high elastic modulus was obtained in the high temperature region. It is clear that the thermal motion of the network chains is significantly suppressed in these cured systems. In addition, in the PPD-cured system, a characteristic pattern like a schlieren texture was clearly observed under the crossed polarized optical microscope. Thus we conclude that the mesogenic group contained in the epoxy molecule is oriented in the networks when the mesogenic epoxy resin is cured with phenols and diamines which have neighboring active hydrogens. On the other hand, the biphenol-type resin cured with 3,3′,5,5′-tetraethyl-4,4′-diamino diphenylmethane (TEDDM) showed a well-defined glass-rubber transition and, thus, a low rubbery modulus. In this cured system, no characteristic pattern was observed under the crossed polarized light. These results show that the large branches, such as ethyl groups on the network chains, prevent the orientation of network chains which contain the mesogenic group. © 1997 John Wiley & Sons, Inc.  相似文献   

16.
A biphenol‐type epoxy resin, which had a mesogenic group in the backbone moiety, was modified with carboxy‐terminated butadiene acrylonitrile copolymer (CTBN) as a reactive elastomer, and its fracture toughness was measured. With the addition of CTBN, the fracture toughness of the biphenol‐type epoxy resin significantly increased and became significantly higher than that of a bisphenol A‐type epoxy resin modified with CTBN. The network chain orientation in the cured biphenol‐type epoxy resin system was clearly observed during the fracture process with polarized microscopy Fourier transform infrared measurements, although such a phenomenon was not observed in the bisphenol A‐type epoxy resin system. The high toughness of the cured biphenol‐type system was clearly due to the consumption of the mechanical energy by a large deformation of the matrix resin due to the orientation of the network chains during the fracture process. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1198–1209, 2003  相似文献   

17.
A novel crystalline epoxy resin—4-(p-glycidyloxyphenoxy)-4′-glycidyloxybiphenyl (DGEBP) was synthesized via a four-step procedure on base 4,4′-biphenol as the starting material. The obtained epoxy exhibited good crystallinity with a melting point of 165.7°C. A monoclinic crystal phase was elucidated by a single crystal X-ray diffraction measurement. The curing behavior of DGEBP with a commercial phenol-4,4′-dimethylbiphenylene novolac resin (trade name GPH65) as the hardener was investigated. For comparison, another two epoxy systems based on the same hardener and two commercially-available biphenyl-containing epoxy resins, including a crystalline epoxy compound, 3,3′,5,5′-tetramethyl-4,4′-dihydroxybiphenyl diglycidyl ether (trade name: YX4000H) and an amorphous 4,4′-dimethylbiphenylene type epoxy resin (trade name NC3000H) were also prepared. It was found that the DGEBP/GPH65 formulation exhibited a superior melt flow behavior to those of YX4000H/GPH65 and NC3000/GPH65 systems. DGEBP/GPH65 epoxy formulation exhibited a minimum melt viscosity of 0.12 Pa s at 150°C. This value is obviously lower than those of YX4000H/GPH65 (0.27 Pa s) and NC3000H/GPH65 (0.59 Pa s) systems. The cured DGEBP/GPH65 thermoset exhibited good thermal stability with a glass transition temperature of 123°C and a 5% weight loss temperature of 415°C. In addition, the DGEBP/GPH65 thermoset possessed good tensile and flexural properties, low water uptake, good dielectric properties and flame retardancy.  相似文献   

18.
A new procedure for the calculation of solubility parameter evolution during polymerisation has been developed for amine‐cured epoxy systems, which allows quantitative thermodynamic modelling of chemically induced phase separation (CIPS). Solubility parameters calculation, chemical analysis based on near infrared spectroscopy and curing kinetics results obtained by differential scanning calorimetry will allow to model the evolution of the Flory–Huggins interaction parameter in amine‐cured epoxy blends. The resin system investigated was based on a diglycidyl ether bisphenol A (DGEBA) epoxy resin cured with isophorone diamine (IPD) blended with various reactive epoxydised dendritic hyperbranched polymer modifiers (HBP), yielding a CIPS‐controlled morphology. The analysis showed the evolution of the different contributions to the solubility parameters to follow the polymerisation kinetics. The dispersive contribution had the highest value at all stages of polymerisation, but the hydrogen and polar contributions showed the largest variation. By evaluating the dynamic evolution of the solubility parameter components, the Flory–Huggins interaction parameter in the epoxy resin‐hyperbranched polymer blends has been modelled as a function of time. This procedure, combined with thermodynamic modelling, will enable to predict phase diagrams in CIPS thermosetting blends quantitatively. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1883–1892, 2000  相似文献   

19.
2,5‐Bis‐(3,4‐dicarboxyphenylcarboxyethoxy)‐4′‐nitrostilbene dianhydride was prepared and reacted with 1,4‐phenylenediamine, 4,4′‐oxydianiline, 4,4′‐diaminobenzanilide, and 4,4′‐(hexafluoroisopropylidene)dianiline to yield unprecedented novel T‐type polyimides ( 4 – 7 ) containing 2,5‐dioxynitrostilbenyl groups as nonlinear optical chromophores, which constituted parts of the polymer backbones. 4 – 7 were soluble in polar solvents such as acetone and N,N‐dimethylformamide. They showed thermal stability up to 300 °C in thermogravimetric analysis thermograms; the glass‐transition temperatures obtained from differential scanning calorimetry thermograms were around 153 °C. The second harmonic generation (SHG) coefficients (d33) of poled polymer films at the 1064‐cm?1 fundamental wavelength were around 4.35 × 10?9 esu. The dipole alignment exhibited exceptionally high thermal stability even at 45 °C higher than the glass‐transition temperature, and there was no SHG decay below 200 °C because of the partial main‐chain character of the polymer structure, which was acceptable for nonlinear optical device applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3189–3199, 2004  相似文献   

20.
A novel flame retardant curing agent for epoxy resin (EP), i.e., a DOPO (9,10-dihydro-9-oxa-10-phosphaphenan-threne-10-oxide)-containing 4,4'-bisphenol novolac (BIP-DOPO) was synthesized and characterized by Fourier transform infrared (FTIR), 1H NMR, 31P NMR spectroscopy, and gel permeation chromatography. The epoxy resin cured by BIP-DOPO itself or its mixture with a commonly used bisphenol A-formaldehyde novolac resin (NPEH720) was prepared. The flame retardancy of the cured EP thermosets were studied by limiting oxygen index (LOI), UL 94 and cone calorimeter test (CCT), and the thermal properties by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results show that the cured epoxy resin EPNP/BI/3/1, which contains 2.2% phosphorus, possesses a value of 26.2% and achieves the UL 94 V-0 rating. The data from cone calorimeter test demonstrated that the peak release rate, average heat release rate, total heat release decline sharply for the flame retarded epoxy resins, compared with those of pure ones. DSC results show that the glass-transition temperatures of cured epoxy resins decrease with increasing phosphorus content. TGA indicates that the incorporation of BIP-DOPO promotes the decomposition of epoxy resin matrix ahead of time and leads to higher char yield. The surface morphological structures of the char residues reveal that the introduction of BIP-DOPO benefits to the formation of a continuous and solid char layer on the epoxy resin material surface during combustion.  相似文献   

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