Fibre reinforced composites of multifunctional epoxy resins

Glass and carbon fibre reinforced epoxy composites were fabricated for N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenyl methane (TGDDM) and its formulated systems with tri- and di-functional reactive epoxy diluents using 30% diaminodiphenyl sulphone (DDS) as a curing agent. The epoxy laminates were evaluated for their physical, chemical and mechanical properties [at room (26°C) and high (100°C) temperatures]. A marginal increase (<20%) in the mechanical properties of CFRP was found compared with GFRP laminates. Incorporation of epoxy diluents altered the mechanical properties of the composites significantly. The incorporation of triglycidyl-4-aminophenol diluent to TGDDM systems resulted in an improvement in mechanical properties of about 2–6%.     

Carbon fiber cardanol-epoxy composites

Carbon fiber composites based on tetrafunctional epoxy resin N,N,N′,N′-tetraglycidyl-2,2-bis[4-(4-aminophenoxy)phenyl]propane modified with cardanol were investigated. The differential scanning calorimetric technique was used to study the curing reaction of the neat resins. The dielectric properties of the composites were compared. The use of cardanol in epoxy resins at cardanol/epoxy molar ratios less than 0.3/1 improved the chemical resistance as well as the mechanical properties of the composites, such as the flexural strength and modulus, tensile strength and modulus, and interlaminar shear strength. Higher cardanol contents decreased such properties. The highest properties of the composites were observed with the epoxy-cardanol resin having a cardanol/epoxy molar ratio of 0.3/1. © 1996 John Wiley & Sons, Inc.     

Blue organic light-emitting diodes using novel spiro[fluorene-benzofluorene]-type host materials

Deep blue colored, fluorescent, spiro-type host materials, 5-[4-(1-naphthyl)phenyl]-spiro[fluorene-7,9′-benzofluorene] and 5,9-bis[4-(1-naphthyl)phenyl]-spiro[fluorene-7,9′-benzofluorene] were designed and successfully prepared by the Suzuki reaction. The electroluminescence characteristics of the two compounds as blue host materials doped with blue dopant materials, diphenyl[4-(2-[1,1;4,1]terphenyl-4-yl-vinyl)phenyl]amine and 1,6-bis[(p-trimethylsilylphenyl)amino]pyrene (SPP) were evaluated. The device used comprised ITO/N,N′-bis-[4-(di-m-tolylamino)phenyl]-N,N′-diphenylbiphenyl-4,4′-diamine)/bis[N-(1-naphthyl)-N-phenyl]benzidine/Host:5% dopant/tris(8-hydroxyquinolinato)aluminium/Al–LiF. The device obtained from 5-[4-(1-naphthyl)phenyl]-spiro[fluorene-7,9′-benzofluorene] doped with 1,6-bis[(p-trimethylsilylphenyl)amino]pyrene displayed high color purity (0.138, 0.138) and high efficiency (3.70 cd/A at 7 V).     

Epoxy resins based on aromatic glycidylamines. VI. Toughening of N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane by reactive additives

Mechanical properties of N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane and its mixtures with liquid bisphenol A-type epoxy resins, bisphenol A and ε-caprolactone have been studied. 4,4′-Diaminodiphenylsulfone was used as hardener. Materials with improved fracture toughness and good mechanical strength in the temperature range 20–200°C have been formulated.     

Effect of structure of aromatic diamines on curing characteristics,thermal stability,and mechanical properties of epoxy resins. I

The curing behavior of diglycidyl ether of bisphenol-A (DGEBA) with aromatic diamines having aryl–ether, aryl–ether–carbonyl, and aryl–ether–sulfone linkages was studied using differential scanning calorimetry (DSC). Aromatic diaminessuch as 1,3-bis(aminophenoxy)benzene (R), 1,4-bis(aminophenoxy)benzene (H),2,2′-bis[4-(4-aminophenoxy)phenyl]propane (B), 4,4′-bis(4-aminophenoxy)benzo-phenone (P), and bis[4-(4-aminophenoxy)phenyl]sulfone (S) were synthesized and characterized in the laboratory. Curing of DGEBA was done using both stoichiometric and nonstoichiometric amounts of diamines and the reaction was monitored using DSC. The reactivity of the diamines depended on the structure. The presence of electron withdrawing groups, even though significantly apart from the reaction site, reduced the nucleophilicity. No significant change was observed in the activation energy for curing, which was around 56 ± 2 kJ/mol. The glass transition temperature of the epoxy network depended on the structure and was higher when diamines P and S were used in comparison to diamines R, H, and B. The cured resins were stable up to 300°C, and maximum char yield (i.e., 32% at 600°C) was obtained in DGEBA cured with diamine P. The room temperature mechanical properties only changed marginally with the structure of the diamines. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1759–1766, 1998     

Blue light-emitting diodes from 2-(10-naphthylanthracene)-spiro[fluorene-7,9′-benzofluorene] host material

A novel, spiro-type host material 2-(10-naphthylanthracene)-spiro[fluorene-7,9′-benzofluorene] was prepared by reacting 2-bromo-spiro[fluorene-7,9′-benzofluorene] with 9-(2-naphthylanthracene)-10-boronic acid via the Suzuki reaction. 2-4′-(Phenyl-4-vinylbenzeneamine)phenyl-spiro[fluorene-7,9′-benzofluorene], 4-[2-naphthyl-4′(phenyl-4-vinylbenzeneamine)]phenyl and diphenyl-[4-(2-[1,1;4,1]terphenyl-4-yl-vinyl)-phenyl]-amine were used as dopant materials. Devices with the configuration of ITO/N,N′-bis[4-(di-m-tolylamino)phenyl]-N,N′-diphenylbiphenyl-4,4′-diamine)/bis[N-(1-naphthyl)-N-phenyl]benzidine/2-(10-naphthylanthracene)-spiro[fluorene-7,9-benzofluorene]:5% dopant/aluminum tris(8-hydroxyquinoline)/Al-LiF showed a maximum power efficiency of 3.7 cd/A at 17.93 mA/cm² and a maximum luminance of 5018 cd/m² at 10 V with a turn-on voltage of 4.5 V.     

Curing kinetics and thermal properties of diglycidylether of bisphenol A with various diamines

To prepare a high‐performance epoxy, we synthesized three types of diamines {N,N′‐(4,4′‐diphenylether)‐bis(4‐aminophthalimide), 4,4′‐bis(p‐aminophenoxy)dibenzalphentaerythriol, and 2,2′‐bis[4‐(p‐aminobenzoyl)phenyl]propane} as epoxy curing agents with a two‐step reaction sequence. The structures of the synthesized diamines were confirmed with Fourier transform infrared and nuclear magnetic resonance spectroscopy. The curing kinetics and thermal stability of the cured epoxy resin with diglycidylether of bisphenol A were estimated with differential scanning calorimetry and thermogravimetric analysis under a nitrogen atmosphere. The kinetics parameters were determined with the Ozawa and Kissinger equations. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 279–284, 2001     

聚酰亚胺-环氧树脂胶黏剂的固化动力学研究

以2,2-双[4-(4-氨基苯氧基)苯基1丙烷(BAPOPP)和2,2-双[4-(3,4-二羧基苯氧基)苯基]丙烷二酐(BPADA)为原料在室温下于DMAe溶剂中合成了一种新型聚酰亚胺,并用其改性环氧树脂体系获得聚酰亚胺-环氧体系胶黏剂.利用差示扫描量热计(DSC),以不同的升温速率对聚酰亚胺-环氧树脂胶黏剂进行DSC...     

Preparation and characterization of organosoluble polyimides based on 1,1-bis[4-(3,4-aminophenoxy)phenyl]cyclohexane and commercial aromatic dianhydrides

A bis(ether amine) III-A containing a cyclohexane cardo group, 1,1-bis[4-(4-aminophenoxy)phenyl]cyclohexane, was synthesized and used as a monomer to prepare polyimides VI-A with six commercial dianhydrides via three different procedures. The intermediate poly(amic acid)s had inherent viscosities of 0.83–1.69 dL g⁻¹ and were thermally or chemically converted into polyimides. Polyimides were also prepared by high-temperature direct polymerization in m-cresol and had inherent viscosities higher than the thermally or chemically cyclodehydrated ones. To improve the solubility of polyimides, six copolyimides were also synthesized from bis(ether amine) III-A with a pair of dianhydrides, which contained 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride or 4,4′-hexafluoroisopropylidenediphthalic anhydride. Series VI-A polyimides were characterized by the good physical properties of their film-forming ability, thermal stability, and tensile properties. A comparative study of the properties, with the corresponding polyimides derived from 2,2-bis[4-(4-aminophenoxy)phenyl]propane, is also presented. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2750–2759, 2001     

聚酰亚胺齐聚物改性胶粘剂的制备及性能研究

利用2,2-双[4-（4-氨基苯氧基）苯1丙烷及偏苯三酸酐合成聚酰亚胺齐聚物,并用此齐聚物改性环氧树脂胶粘剂。使用红外光谱、凝胶化时间、接触角和拉伸剪切强度对改性胶粘剂性能进行表征。结果表明,齐聚物的加入对环氧树脂固化反应具有促进作用;当100质量份环氧中加入16份齐聚物时,胶粘剂力学性能最佳;当齐聚物用量为20份时;胶粘剂表面能最高。     

Epoxy resins based on aromatic glycidylamines. V. Shelf life of TGDDM-based epoxy resins

The effect of aging on resin composition was investigated as a part of a study concerned with the evaluation of epoxies containing N, N, N′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM). Long-term stability of three different epoxy resins based on TGDDM and their mixtures with 4,4′-diaminodiphenylsulfone (DDS) was followed at 23 ± 2°C at a relative humidity ranging from 45% to 55%, by means of GPC and HPLC; short-term stability of the resins was evaluated at 125°C.     

Low-dielectric-constant aromatic homopolyimide and copolyimide derived from pyromellitic dianhydride, 4,4′-oxydianiline, 2,2-bis[4-(4-aminephenoxy)phenyl]propane, 1,4-bis(4-aminophenoxy)benzene,or 1,3-bis(4-aminophenoxy)benzene

Low-dielectric-constant aromatics, homopolyimide and copolyimide, were introduced. Homopolyimides were prepared by pyromellitic dianhydride (PMDA) as an anhydride monomer and 4,4′-oxydianiline (ODA), 2,2-bis[4-(4-aminephenoxy)phenyl]propane, 1,4-bis(4-aminophenoxy)benzene, or 1,3-bis(4-aminophenoxy)benzene as an amine monomer. The copolyimides were prepared with PMDA as an anhydride monomer, ODA as an amine monomer with the addition of 2,2-bis[4-(4-aminephenoxy)phenyl]propane, 1,4-bis(4-aminophenoxy)benzene, or 1,3-bis(4-aminophenoxy)benzene as another amine monomer. The polyimides were well characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, thermomechanical analysis, dielectric measurements, and tensile testing. The homopolyimide and copolyimides showed lower dielectric constants than the homopolyimide formed by ODA and PMDA. The results also indicate that the interchain distance, the quantities of phenyl ether, and the position of the substitute are factors that not only affected the thermal performance of polyimide by improving the molecular flexibility but also reduced the dielectric constant of polyimide by increasing the free volume of the molecular chain and decreasing the polarization points per unit volume. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47405.     

Cure kinetics of multifunctional epoxies with 2,2′‐dichloro‐4,4′‐diaminodiphenylmethane as hardener

The curing behavior of the epoxy resin N,N,N′,N′‐tetraglycidyldiaminodiphenyl methane (TGDDM) with triglycidyl p‐aminophenol as a reactive diluent was investigated using 2,2′‐dichloro‐4,4′‐diaminodiphenylmethane (DCDDM) as the curing agent. The effect of the curing agent on the kinetics of curing, shelf‐life, and thermal stability in comparison with a TGDDM‐diaminodiphenylsulfone (DDS) system was studied. The results showed a lesser activation energy at the lower level of conversion with a broader cure exotherm for the epoxy‐DCDDM system in comparison with the epoxy‐DDS system, although the overall activation energy for the two systems was comparable. TGA studies showed more stability in the epoxy‐DCDDM system than in the epoxy‐DDS system. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2097–2103, 2000     

New fluorinated poly(1,3,4-oxadiazole-ether-imide)s

New fluorinated poly(1,3,4-oxadiazole-ether-imide)s have been prepared by solution polycondensation reaction of different aromatic diamines having preformed 1,3,4-oxadiazole ring, such as 2,5-bis(p-aminophenyl)-1,3,4-oxadiazole, 2,5-bis[p-(4-aminophenoxy)phenyl]-1,3,4-oxadiazole, 2,5-bis[p-(3-aminophenoxy)phenyl]-1,3,4-oxadiazole, 2-(4-dimethylaminophenyl)-5-(3,5-diaminophenyl)-1,3,4-oxadiazole and 2-(4-fluorophenyl)-5-(3,5-diaminophenyl)-1,3,4-oxadiazole, with an aromatic dianhydride incorporating ether linkages and hexafluoroisopropylidene group, namely 1,1,1,3,3,3-hexafluoro-2,2-bis-[(3,4-dicarboxyphenoxy)phenyl]-propane dianhydride. The polymers were easily soluble in polar organic solvents, such as N-methylpyrrolidinone, N,N-dimethylformamide, and pyridine, as well as in certain low boiling-point organic solvents, such as tetrahydrofuran and chloroform. Very thin coatings deposited onto silicon wafers exhibited smooth, pinhole-free surface in atomic force microscopy. The polymers showed high thermal stability with decomposition temperature being above 410 °C. They exhibited a glass transition in the temperature range of 183-217 °C, with reasonable interval between glass transition and decomposition temperature. Solutions of some polymers in N,N-dimethylformamide exhibited blue fluorescence, having maximum emission wavelength in the range of 411-424 nm.     

Modified poly(ether–imide–amide)s with pendent benzazole structures: Synthesis and characterization

Three series of novel modified poly(ether–imide–amide)s (PEIAs) having pendent benzazole units were prepared from diimide–dicarboxylic acids, including 2-[3,5-bis(4-trimellitimidophenoxy) phenyl]benzimidazole, 2-[3,5-bis(4-trimellitimidophenoxy) phenyl]benzoxazole, and 2-[3,5-bis(4-trimellitimidophenoxy) phenyl]benzothiazole, with various diamines by direct polycondensation in N-methyl-2-pyrrolidone with triphenyl phosphite and pyridine as condensing agents. These new diimide–dicarboxylic acids containing ether linkages and benzazole pendent groups were synthesized by the condensation reaction of 5-(2-benzimidazole)-1,3-bis(4-aminophenoxy)benzene, 5-(2-benzoxazole)-1,3-bis(4-aminophenoxy)benzene, or 5-(2-benzothiazole)-1,3-bis(4-aminophenoxy)benzene with trimellitic anhydride, respectively. All of the polymers were obtained in quantitative yields with inherent viscosities of 0.39–0.65 dL/g. For comparative purposes, the corresponding unsubstituted PEIAs were also prepared by the reaction of a diimide–dicarboxylic acid monomer lacking benzazole pendent groups, namely, 3,5-bis(4-trimellitimidophenoxy) phenyl, with the same diamines under similar conditions. The solubilities of the modified PEIAs in common organic solvents and their thermal stability were enhanced compared to those of the corresponding unmodified PEIAs. The glass-transition temperature, 10% weight loss temperature, and char yields at 800°C were 19–31°C, 22–57°C and 4–8% higher, respectively, than those of the unmodified polymers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Phosphorus‐containing epoxy resins: Thermal characterization

Three novel aromatic phosphorylated diamines, i.e., bis N,N′‐{3‐[(3‐aminophenyl)methyl phosphinoyl] phenyl} pyromellitamic acid (AP), 4,4′‐oxo bis N,N′‐{3‐[(3‐aminophenyl)methyl phosphinoyl] phenyl}phthalamic acid (AB) and 4,4′‐hexafluoroisopropylidene‐bis N,N′‐{3‐[(3‐aminophenyl)methyl phosphinoyl] phenyl}phthalamic acid (AF) were synthesized and characterized. These amines were prepared by solution condensation reaction of bis(3‐aminophenyl)methyl phosphine oxide (BAP) with 1,2,4,5‐benzenetetracarboxylic acid anhydride (P)/3,3′,4,4′‐benzophenonetetracarboxylic acid dianhydride (B)/4,4′‐(hexafluoroisopropylidene)diphthalic acid anhydride (F), respectively. The structural characterization of amines was done by elemental analysis, DSC, TGA, ¹H‐NMR, ¹³C‐NMR and FTIR. Amine equivalent weight was determined by the acetylation method. Curing of DGEBA in the presence of phosphorylated amines was studied by DSC and curing exotherm was in the temperature range of 195–267°C, whereas with conventional amine 4,4′‐diamino diphenyl sulphone (D) a broad exotherm in temperature range of 180–310°C was observed. Curing of DGEBA with a mixture of phosphorylated amines and D, resulted in a decrease in characteristic curing temperatures. The effect of phosphorus content on the char residue and thermal stability of epoxy resin cured isothermally in the presence of these amines was evaluated in nitrogen atmosphere. Char residue increased significantly with an increase in the phosphorus content of epoxy network. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2235–2242, 2002     

New optically active poly(amide-imide)s based on N,N′-(pyromellitoyl)-bis-L-amino acid and 1,3-bis(4-aminophenoxy) propane: Synthesis and characterization

Five new poly(amide-imide)s 8a–e were synthesized through the direct polycondensation reaction of five chiral N,N′-(pyromellitoyl)-bis-L -amino acids 3a–e with 1,3-bis(4-aminophenoxy) propane 7 in a medium consisting of N-methyl-2-pyrrolidone, triphenyl phosfite, calcium chloride, and pyridine. The polycondensation reaction produced a series of novel poly(amide-imide)s containing trimethylene moiety in the main chain in high yield with inherent viscosities between 0.34 and 0.65 dL/g. The resulted polymers were fully characterized by means of FTIR spectroscopy, elemental analyses, inherent viscosity, and solubility tests. Thermal properties of these polymers were investigated by using thermal gravimetric analysis (TGA) and differential thermal gravimetric (DTG). All of the polymers were soluble at room temperature in polar solvents such as N,N-dimethyl acetamide, N,N-dimethyl formamide, dimethyl sulfoxide, and N-methyl-2-pyrrolidone. N,N′-(pyromellitoyl)-bis-L -amino acids 3a–e were prepared in quantitative yields by the condensation reaction of pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic acid 1,2,4,5-dianhydide) 1 with L -alanine 2a , L -valine 2b , L -leucine 2c , L -isoleucine 2d , and L -phenyl alanine 2e in acetic acid. Also 1,3-bis(4-aminophenoxy) propane 7 was synthesized by using a two-step reaction. At first 1,3-bis(4-nitrophenoxy) propane 6 was prepared from the reaction of 4-nitrophenol 4 with 1,3-dibromoprapane 5 in NaOH solution. Then, dinitro compound 6 was reduced by using Na₂S. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Organosoluble, Low-Colored Fluorinated Polyimides Based on 1,1-Bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane

A novel trifluoromethyl-substituted bis(ether amine) monomer, 1,1-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane, was synthesized that led to a series of novel fluorinated polyimides via chemical imidization route when reacted with various commercially available aromatic tetracarboxylic dianhydrides. These polyimides were highly soluble in a variety of organic solvents such as N-methyl-2-pyrrolidone and N,N -dimethylacetamide, and most of them could afford transparent, low-colored, and tough films. These polyimides exhibited glass-transition temperatures (T _gs) of 227–269 °C and showed no significant decomposition below 500 °C under either nitrogen or air atmosphere. These polyimides had low dielectric constants of 2.87–3.17 at 10 kHz, low water uptake of 0.13%–0.58%, and an ultraviolet-visible absorption cutoff wavelength at 364–410 nm. For a comparative study, a series of analogous polyimides based on 1,1-bis[4-(4-aminophenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane were also prepared and characterized.     

Preparation and properties of novel soluble aromatic polyetherimides from 1,1′-bis[4-(3,4-dicarboxyphenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane dianhydride and aromatic diamines

New aromatic polyetherimides containing the 1,1′-bis[4-(3,4-dicarboxyphenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane dianhydride unit were prepared by a conventional two-step method from 1,1′-bis[4-(3,4-dicarboxyphenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane dianhydride and several diamines. This procedure yielded high molecular weight polyetherimides with inherent viscosities of 0.22–1.29 dL/g. Most of the corresponding polyetherimides were soluble in organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, N,N-dimethylacetamide, and methylene chloride under ambient temperature. The glass transition temperatures (T_g) of these polymers were in the range of 207–264°C and the temperatures of 10% weight loss were over 520°C at a heating rate 20°C/min in nitrogen. © 1996 John Wiley & Sons, Inc.     

Epoxy systems with improved water resistance,and the non-fickian behaviour of epoxy systems during water ageing

N,N-Bis (2, 3-epoxypropyl) aniline and 4,4′-methylenebis-[N,N-bis (2,3-epoxypropyl) aniline] containing bromo, chloro, trifluoromethyl or polyfluoroalkoxy substituents were synthesised and cured with aromatic diamines in order to investigate the effect of substituted halogen on water absorption. Significant improvements were achieved: thus use of 4,4′-methylenebis-[N, N-bis (2, 3-epoxypropyl)-3, 5-dichloroaniline] and 4,4′-methylenebis-[N,N-bis (2,3-epoxypropyl)-3-(trifluoromethyl) aniline] instead of 4,4′-methylenebis-[N,N-bis (2,3-epoxypropyl) aniline] reduced the water absorption by about a half. Departures from Fickian behaviour were observed during water immersion ageing at room temperature and were a general feature of the epoxy systems examined. Plots of water absorption against the Fickian parameter (√t/d) usually showed at least mild sigmoid character and were not independent of specimen thickness. Further, slow continued uptake of water occurred during long-term ageing, and evidence is provided that the associated network distortions are reversible.