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1.
John A. Mikroyannidis Anastasios P. Melissaris 《Journal of polymer science. Part A, Polymer chemistry》1988,26(5):1405-1418
Novel phosphorylated bismaleimides and nonphosphorylated tetramaleimides containing substituted s-triazine rings (chain-extended by imide, amide, or urea groups) were prepared and polymerized. These polymer precursors were prepared by reacting 2,4-bis(4-aminophenoxy)-6-diethoxyphosphinyl-s-triazine or 2,4,6-tris(4-aminophenoxy)-s-triazine with maleic anhydride in combination with a bridging agent such as pyromellitic or benzophenone tetracarboxylic dianhydride, terephthaloyl chloride, and tolylene diisocyanate. The structure of polymer precursors was confirmed by infrared (IR) and proton nuclear magnetic resonance (1H-NMR) spectroscopy and their curing behavior was investigated by differential thermal analysis (DTA). The phosphorylated bismaleimides were thermally polymerized at a lower temperature than did the corresponding nonphosphorylated tetramaleimides. Dynamic thermogravimetric analysis (TGA) showed that the nonphosphorylated and phosphorylated cured resins were stable up to 320–370 and 312–327°C, respectively, in nitrogen or air atmosphere. In addition, the latter afforded a relatively higher char yield. The relative thermal and thermooxidative stability of polymers with regard to the chemical structure of the bridging group was of the order imide > amide > urea. Upon isothermal aging the phosphorylated polymers exhibited a lower weight loss than did the corresponding nonphosphorylated polymers. 相似文献
2.
Devendra Kumar George M. Fohlen John A. Parker 《Journal of polymer science. Part A, Polymer chemistry》1984,22(4):927-943
High-strength fire- and heat-resistant polymers were obtained by the thermally induced melt-polymerization of maleimido-phenoxy cyclotriphosphazenes linked by hexafluoroisopropyliden-ediphthalimide groups. These polymers show good thermal stability and high char yields: 78–80% at 800°C in nitrogen and 60–68% in air at 700°C. Graphite-fabric laminates did not burn in pure oxygen, even at 300°C (LOI = 100%), and were tested for shear, flexural, and tensile strengths. Two monomers were synthesized by reacting tris(4-aminophenoxy)-tris(phenoxy) cyclotriphosphazene with maleic anhydride and hexafluoroisopropylidenediphthalic anhydride. The triamine was synthesized by a stepwise reaction of hexachlorocyclotriphosphazene with phenol and 4-nitrophenol to give tris(4-nitrophenoxy)-tris(phenoxy)cyclotriphosphazene and reducing the nitro groups. The structures of cyclic phosphazene-trimeric precursors and the polymers were characterized by FT-IR, 1H-NMR, 31P-NMR, and mass spectroscopy. The curing behaviors of polymer precursors were evaluated by differential scanning calorimetry and thermogravimetric analyses. 相似文献
3.
Reaction of RMgCl [R = (Me3Si)2CH) with SbCl3 affords RSbCl2. Also R2SbCl reacts with RLi to yield R3Sb, while R′SbCl2 [R′ = (Me3Si)3C] is synthesized from R′Li and SbCl3. Mass spectra of RSbCl2 and R′SbCl2 show that fragmentations proceed with elimination of Me3SiCl. The chlorides RSbCl2, R2SbCl and R′SbCl2 are thermally very stable. 相似文献
4.
Hyperbranched, aliphatic polyesters of theoretically calculated molar masses 1 200–44 300 (2–7 generations) were synthesized in the molten state from 2, 2-bis(hydroxymethyl)propionic acid (bis-MPA) (repeating unit of ABx-type) and 2-ethyl-2-(hydroxymethyl)-1, 3-propanediol (TMP) (core molecule) using acid catalysis. The synthetic procedure was a pseudo-one-step divergent reaction. The degree of branching was found to be near 80 %. A study has also been made with respect to the rheological properties of the hyperbranched aliphatic polyesters. The polymers exhibit an almost newtonian behaviour in the molten state. They also exhibit a lower increase in viscosity with molecular weight than linear polymers. The surface functionality is shown to greatly affect the viscosity of the polymers. 相似文献
5.
Devendra Kumar Alka D. Gupta Mrignaini Khullar 《Journal of polymer science. Part A, Polymer chemistry》1993,31(3):707-713
A novel class of fire- and heat-resistant matrix resins has been synthesized by thermal polymerization of ethynyl-substituted aromatic cyclotriphosphazenes. Thermal polymerization of new tris[4-(4′-ethynylbenzanilido)phenoxy]tris(phenoxy) cyclotriphosphazene ( III ) and tris[4-(4′-ethynylphthalimido)phenoxy]tris(phenoxy)cyclotriphosphazene ( VII ) at 250°C for 1–1.5 h gave tough polymers. The thermal stabilities of the polymers were evaluated in nitrogen and in air by thermogravimetric analysis (TGA). The synthesised polymers were stable to 400–410°C and showed char yield of 78–65% at 800°C in nitrogen and of 78–69% at 700°C in air. The ethynyl-substituted polymer precursor ( III ) was synthesised by the reaction of tris(4-aminophenoxy)tris(phenoxy)cyclotriphosphazene ( I ) with 4-ethynylbenzoyl chloride. The polymer precursor ( VII ) was synthesised by a solution condensation of I with 4-ethynylphthalic anhydride followed by in situ thermal cyclodehydration at 150°C. The structure of polymer precursors was characterized using proton nuclear magnetic resonance (1H-NMR), infrared (IR) spectroscopy, and elemental analysis. The curing of polymer precursors was monitored by differential scanning calorimetery (DSC) and IR spectroscopy. The synthesised matrix resins are potential candidates for the development of heat- and fire-resistant fiber-reinforced composites. © 1993 John Wiley & Sons, Inc. 相似文献
6.
Guerra KP Delgado R Drew MG Félix V 《Dalton transactions (Cambridge, England : 2003)》2006,(34):4124-4133
New N-(3-aminopropyl) (L1, L2) and (2-cyanoethyl) (L3, L4) derivatives of a 14-membered tetraazamacrocycle containing pyridine have been synthesized. The protonation constants of L1 and L2 and the stability constants of their complexes with Ni2+, Cu2+, Zn2+ and Cd2+ metal ions were determined in aqueous solutions by potentiometry, at 298.2 K and ionic strength 0.10 mol dm(-3) in KNO3. Both compounds have high overall basicity due to the presence of the aminopropyl arms. Their copper(II) complexes exhibit very high stability constants, which sharply decrease for the complexes of the other studied metal ions, as usually happens with polyamine ligands. Mono- and dinuclear complexes are formed with L2 as well as with L1, but the latter exhibits mononuclear complexes with slightly higher K(ML) values while the dinuclear complexes of L2 are thermodynamically more stable. The presence of these species in solution was supported by UV-VIS-NIR and EPR spectroscopic data. The single crystal structures of [Cu(H2L2)(ClO4)]3+ and [CoL3Cl]+ revealed that the metal centres are surrounded by the four nitrogen atoms of the macrocycle and one monodentate ligand, adopting distorted square pyramidal geometries. In the [CoL3Cl]+ complex, the macrocycle adopts a folded arrangement with the nitrogen atom opposite to the pyridine at the axial position while in the [Cu(H2L2)(ClO4)]3+ complex, the macrocycle adopts a planar conformation with the three aminopropyl arms located at the same side of the macrocyclic plane. 相似文献
7.
Guerra KP Delgado R Lima LM Drew MG Felix V 《Dalton transactions (Cambridge, England : 2003)》2004,(12):1812-1822
Two N-methylphosphonic acid derivatives of a 14-membered tetraazamacrocycle containing pyridine have been synthesized, H(4)L(1) and H(6)L(2). The protonation constants of these compounds and the stability constants of complexes of both ligands with Ni(2+), Cu(2+) and Zn(2+) were determined by potentiometric methods at 298 K and ionic strength 0.10 mol dm(-3) in NMe(4)NO(3). The high overall basicity of both compounds is ascribed to the presence of the phosphonate arms. (1)H and (31)P NMR spectroscopic titrations were performed to elucidate the sequence of protonation, which were complemented by conformational analysis studies. The complexes of these ligands have stability constants of the order of or higher than those formed with ligands having the same macrocyclic backbone but acetate arms. At pH = 7 the highest pM values were found for solutions containing the compound with three acetate groups, followed immediately by those of H(6)L(2), however, as expected, the increasing pH favours the complexes of ligands containing phosphonate groups. The single-crystal structure of Na(2)[Cu(HL(1))]NO(3)x8H(2)O has shown that the coordination geometry around the copper atom is a distorted square pyramid. Three nitrogen atoms of the macrocyclic backbone and one oxygen atom from one methylphosphonate arm define the basal plane, and the apical coordination is accomplished via the nitrogen atom trans to the pyridine ring of the macrocycle. To achieve this geometric arrangement, the macrocycle adopts a folded conformation. This structure seems consistent with Uv-vis-NIR spectroscopy for the Ni(2+) and the Cu(2+) complexes and with the EPR for the latter. 相似文献
8.
Electro-conductive resins, convenient for casting and coating applications were investigated in this paper.Electrical conductivity of epoxy and polyurethane resins, filled with two different grades of synthetic graphite (different average size) was studied. It was found that all the investigated composites became electro-conductive when filled with 22-vol% of the filler.The impact strength of epoxy and polyurethane resins filled with graphite was also investigated. A decrease in impact strength with an increase in filler content was observed in all cases. The highest values of impact strength were found for polyurethane/graphite KS 6 composites.The strength of adhesion of the filled resins to aluminum was also determined. A decrease in the strength of adhesive joints to aluminum foils with an increase in filler content was observed in all cases. The strongest adhesive joints were found for the epoxy/graphite KS 6 composites. 相似文献
9.
R. M. Shaker A. F. Mahmoud F. F. Abdel-Latif 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):397-406
Abstract The terephthalic acid hydrazide(1) reacted with phenyl/benzyl isothiocyanate2a,bto yield the corresponding bis-thiosemicarbazides4a,b,viaacid hydrolysis of the intermediate 3whereas cyclization of4gave the bis-1,2,4-triazoles 5,6and bis-1,3,4-thiadiazoles7,8. Similarly, compound 1reacted with phenyl isocyanate9to give the bis-semicarbazide10, which was cyclized to the bis-oxadiazole 11and/or bis-1,2,4-triazole12in POClti3and NaOH respectively. 相似文献
10.
John A. Mikroyannidis 《Journal of polymer science. Part A, Polymer chemistry》1997,35(8):1353-1361
3-(4-Aminophenyl)-5-(3-aminophenyl)-2-pyrazoline as well as the 1-acetyl- or 1-benzoyl-substituted derivatives of this compound were synthesized and used for preparing a new series of polyamides and polyimides. Characterization of polymers was accomplished by inherent viscosity, 1H-NMR, 13C-NMR, x-ray, DTA, TMA, TGA, and isothermal gravimetric analysis. The properties of polymers were correlated with their chemical structures. They were amorphous or microcrystalline and soluble in polar aprotic solvents, CCl3COOH, and m-cresol. The polyamides showed an excellent solubility being soluble even in o-dichlorobenzene, 1,2-dichloroethane, and chloroform. The polymers displayed Tg at 127–163°C and softening at 150–195°C. The polyamide bearing unsubstituted pyrazoline moieties was remarkably more hydrophilic than those containing 1-acetyl- or 1-benzoyl-substituted pyrazoline segments. Upon curing, crosslinked polymers were obtained and their thermal stability was evaluated. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1353–1361, 1997 相似文献
11.
Fire-retardant formulations for wood were developed, and the efficiency of their fireproofing properties, resistance to water,
thermal decomposition, and effect of additives on these properties were studied. 相似文献
12.
The high propensity of organosilanes towards polycondensation and reaction with nucleophilic moieties has facilitated the formation of new organic-inorganic hybrids based on the lacunary divacant heteropolyanion [gamma-SiW10O36]8-. Depending on the experimental conditions two different types of derivatives were obtained with the general formula [gamma-SiW10O36(RSi)2O]4- (1) (>90% yield) and [gamma-SiW10O36(RSiO)4]4- (2) (>85% yield) (R = H (1a, 2a), vinyl (1b), -C3H6OC(O)C-(Me)=CH2 (1c, 2c), phenyl (1d, 2d)). The structures of the hybrid anions have been inferred from spectroscopic data, in particular from multinuclear (29Si and 183W) NMR solution studies and from MALDI-TOF mass spectrometry. Both species correspond to the grafting of an oxo-bridged siloxane unit onto the surface of the lacunary polyoxoanion. 相似文献
13.
In this study, novel bio-based hydroxyl-end-capped (co)polyesters from dimethyl-2,5-furandicarboxylate (DMF), 2,3-butanediol, and a variety of comonomers viz. glycerol, pentaerythritol or trimethylolpropane are prepared using a solvent-free, bulk polycondensation technique. Extensive molecular and thermal characterization was performed to elucidate the properties of these materials. The materials showed suitable properties for solvent-borne coating applications in terms of their molecular weight, functionality and thermal characteristics, and coatings were prepared using the isocyanurate of hexamethylene diisocyanate as a cross-linker. The resulting coatings, having thicknesses between 30 and 55 μm, were hard but rather brittle. All the coatings have good solvent resistance, pointing to sufficient network formation. It is clear that the presented DMF-based polyesters show promise as bio-based coating resins. 相似文献
14.
The thermal degradation process of a commercial intumescent epoxy resin for fireproofing applications was investigated. The changes in the morphology of the material during exposure to fire-like conditions were interpreted in the light of the degradation of single material components and of the overall swelling mechanism. An apparent kinetic model was developed to describe the thermally activated conversion and the weight loss of the material. The dramatic change in the key properties of the material (thermal conductivity, volume swelling, and apparent density) was investigated and linked with the thermal degradation phenomena governing the swelling process. Models were developed to describe material properties as a function of temperature and material conversion. The models provide the simulation of the fire-triggered degradation of the sample material at the heating rates of interest, allowing a detailed analysis of fireproofing performance. 相似文献
15.
Addition of organocuprates to α,β-enones which possess on the β′-carbon a heteroatom substituent leads in good to excellent yield to β,β′-dialkylated ketones. This process is termed bis-β,β′-conjugate addition. 相似文献
16.
T.M. Schmidt C. Bianchini M.M.C. Forte S.C. Amico A. Voronoff R.C.F. Gonalves 《Polymer Testing》2006,25(8):1044-1051
The use of polyester (PET) fibre ropes in mooring applications for deep water oil platforms implies the use of terminations, e.g. the spliced eye, which demands specialized manual labour and is time consuming. This research evaluates the technical viability of substituting these terminations with a resin socketing procedure, which consists of introducing a simple-end rope in a hollow metallic device having a conical shape (i.e. a socket) and pouring into it a thermoset resin that, once cured, fastens the rope extremity. PET ropes (10 or 48 mm diameter) were socketed and evaluated under tensile testing. The curing and viscoelastic behaviour of various epoxy resin systems were monitored with DSC and DMA. The performance of socketed PET ropes was suitable for the intended application, showing failure loads similar to those of unsocketed ropes, being particularly dependant on resin type, socket conicity and resin/fibre volumetric ratio in it. 相似文献
17.
Fernanda M.B. Coutinho Márcia A.F.S. Neves Marcos L. Dias 《Macromolecular Symposia》2002,189(1):27-44
Improvements in the synthesis of porous polymers for different applications have been carried out in our laboratory. Beads of poly(styrene-co-divinylbenzene) with morphology adequate to the application at hand were prepared. Packing materials for size exclusion chromatography (SEC) weve prepared by single-step swelling and polymerization (SSWP) and by modified suspension polymerization (MSP). High values of exclusion limit (106 and 8.0x106) were attained for SEC columns packed with poly(styrene-co-divinylbenzene) synthesized using high proportions of polystyrene, as porogen agent and divinylbenzene. The maximum values of exclusion limits were attained for SEC columns packed with beads prepared by SSWP method. 相似文献
18.
Narender K. Kaushik Bharat Bhushan Gurdeep R. Chhatwal 《Transition Metal Chemistry》1978,3(1):215-217
Summary Titanium(IV)N,N-dialkyldithiocarbamates of the type 5-Cp2Ti (S2CNR2)Cl and (5-MeCp)2Ti(S2CNR2)Cl (R = Me, Et and i-Pr) have been prepared by the reaction of di--cyclopentadienyldichlorotitanium(IV) and bis-n-methylcyclopentadienyldichlorotitanium(IV) with sodium salts of dithiocarbamic acids in refluxing dichloromethane. Molecular weight, conductance and i.r. studies show these complexes to be monomeric nonelectrolytes in which the dithiocarbamate ligands are bidentate. Therefore, pentacoordination may be assigned to titanium(IV) atom in all six complexes. Electronic and proton n.m.r. studies spectra have also been recorded for the complexes. 相似文献
19.
20.
Extraction and subsequent recovery, in four separate fractions, of naphthenic acids, alkylphenols, pyrrollic compounds and nitrogen bases can be made from petroleum products using macroporous ion-exchange resins. Distinctive features of the technique are the use of dissolved gases in polar solvents as eluants and the application of the carbonate form of anion-exchange resins. The transition metal form of a macroreticular cation exchanger is shown to extract ligands from non-aqueous systems and a specific application to petroleum analysis is given. 相似文献