Benzophenone Tetracarboxylic Acid Research Articles

Preparation and properties of nadic‐end‐capped cyclotriphosphazene‐containing polyimide/carbon fiber composites

AbstractNew novel fire‐resistant and heat‐resistant cyclotriphosphazene‐containing polyimide resins were prepared in situ by the polymerization of (p‐aminophenoxy)(phenoxy)cyclotriphosphazenes with 3,3′,4,4′‐benzophenonetetracarboxylic acid or 3,3′,4,4′‐diphenylsulfonetetracarboxylic acid and a crosslink agent, 5‐norbornene‐2,3‐dicarboxylic acid and were used as polymer matrix compositing with a woven carbon fiber to prepare nadic‐end‐capped cyclotriphosphazene‐containing polyimide/carbon fiber composites. The thermal stability, flame retardance, morphology of the surface fracture, and some physical properties of the composites were investigated by thermogravimetric analysis, scanning electron microscopy, and a material testing system, respectively. The composites had good thermal stability, flame retardance, and mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 810–818, 2003

Fullerene-Modified Polyimide Derived from 3,3',4',-Benzophenonetetracarboxylic Acid and 3,3'-Diaminobenzophenone for Casted Items and Its Use in Tribology

The possibility was examined of processing into a casted item (molding) of the crystallizing thermoplastic polyimide derived from 3,3'-diaminobenzophenone and 3,3',4,4'-benzophenonetetracarboxylic dianhydride and of composites of this polyimide with fullerenes. The tribological characteristics of the moldings were studied.

Phosphorylated Epoxy Resin: Effect of Phosphorus Content on the Properties of Laminates

The paper describes the properties of glass-fabric reinforced composites based on novel phosphorylated epoxy matrix resins. Limiting oxygen index as high as 80 were attained using such novel matrix resins. These resins were prepared by curing diglycidyl ether of bisphenol-A (DGEBA) with phosphorylated amines such as bis(3-aminophenyl) methyl phosphine oxide (B), tris(3-aminophenyl)phosphine oxide (T), bis[3(3′-aminobenzamidophenyl)]-methylphosphine oxide (MB), bis[3(4′-aminobenzamido phenyl)]methylphosphine oxide (PB), tris[3(3′-aminobenzamidophenyl)]phosphine oxide (MT) and tris[3(4′-aminobenzamido phenyl)] phosphine oxide (PT). Phosphorus- containing amide-acid amines were also used for curing and were prepared by reacting T with 1,2,4,5-benzenetetracarboxylic acid anhydride(P); 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride (Z) and 4,4′-(hexafluoroisopropylidene)diphthalic acid anhydride (F). Interlaminar shear strength (ILSS), flexural strength and modulus of composites (32 ± 3% resin content) based on B, T, MB, PB, MT, PT and state-of-the-art curing agent 4,4′-diaminodiphenyl sulfone (D) were higher than the composites prepared using amide-acid amines. Increase in ILSS was observed on heating at 180°C for 200 h. On hygrothermal ageing of the samples for 7 days, the ILSS values decreased but those cured with amide-acid amines showed the least change. A significant improvement in limiting oxygen index (LOI) was observed by increasing the phosphorus content of the composites.

Synthesis and properties of fluorinated polyimides. 3. Derived from novel 1,3-bis[3′-trifluoromethyl-4′(4″-amino benzoxy) benzyl] benzene and 4,4-bis[3′-trifluoromethyl-4′(4-amino benzoxy) benzyl] biphenyl

Novel diamine monomers, 1,3-bis[3′-trifluoromethyl-4′(4″-amino benzoxy) benzyl] benzene (IV) and 4,4-bis[3′-trifluoromethyl-4′(4-amino benzoxy) benzyl] biphenyl (V) have been synthesized. These monomers lead to several novel fluorinated polyimides on reaction with different commercially available dianhydrides like pyromellatic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA) or 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane (6FDA). The polyimides prepared from above two monomers on reaction with 6FDA are soluble in several organic solvents such as N, N-dimethyl formamide (DMF), N, N-dimethyl acetamide (DMAc) and tetrahydrofuran (THF). The polyimides prepared from PMDA/IV is soluble in DMF and N-methyl pyrollidone (NMP) on heating, whereas V/PMDA is insoluble in all solvents. BTDA/IV polyimide is also soluble in NMP, DMF and DMAc. These polyimide films have low water absorption rate 0.2–0.7% and low dielectric constant 2.74–3.2 at 1 MHz. These polyimides showed very high thermal stability even up to 531 °C for 5% weight loss in synthetic air and glass transition temperature up to 316 °C (by DSC) in nitrogen. All polyimides formed tough transparent films, with tensile strength up to 148 MPa, a modulus of elasticity up to 2.6 GPa and elongation at break up to 31% depending upon the exact repeating unit structure.

Effect of structure on thermal behaviour of epoxy resins

The paper deals with the curing behaviour of diglycidyl ether of bisphenol-A (DGEBA) using three novel multifunctional aromatic amines having phosphine oxide and amide–acid linkages. The amines were prepared by reacting tris(3-aminophenyl)phosphine oxide (TAP) with 1,2,4,5-benzenetetracarboxylic acid anhydride (P)/4,4 ′-(hexafluoroisopropylidene)diphthalic acid anhydride (F)/3,3 ′,4,4 ′-benzophenonetetracarboxylic acid dianhydride (B). Amide–acid linkage in these amines is converted to thermally stable imide linkage during curing reaction. Curing temperatures of DGEBA were higher with phosphorylated amines than the conventional amine 4,4 ′-diamino diphenyl sulphone (D). A decrease in initial decomposition temperature and higher char yields were observed when phosphorus containing amide–acid amines were used as curing agents for DGEBA.

Synthesis and properties of fluorinated polyimides, 2

Novel diamine monomers, 2,6-bis(3'-trifluoromethyl-p-aminobiphenyl ether)pyridine (TABP) and 2,5- bis(3'-trifluoromethyl-p-aminobiphenyl ether)thiophene (TABT) have been synthesized, which lead to a number of novel fluorinated polyimides by thermal imidization routes when reacted with different commercially available dianhydrides like pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA) or 2,2-bis(3,4- dicarboxyphenyl) hexafluoropropane (6FDA). The polyimides ABTP/6FDA and ABTT/6FDA are soluble in several organic solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc) and tetrahydrofuran (THF). The polyimide ABTP/PMDA is only soluble in N- methylpyrollidone (NMP) whereas ABTT/PMDA is insoluble in all solvents. The polyimides ABTP/6FDA (2c) and ABTT/6FDA (3c) exhibited number-average molecular weight 32 940 (polydispersity index (PDI), 1.97) and 24 760 (PDI, 1.87) respectively. These polyimide films have low water absorption rate 0.3-0.9% and low dielectric constant 2.92-3.29 at 1 MHz. These polyimides showed very high thermal stability even up to 532 °C for 5% weight loss in synthetic air and glass transition temperature up to 287 °C (by DSC) in nitrogen. All polyimides formed tough transparent films, with tensile strength up to 115 MPa, a modulus of elasticity up to 2.91 GPa and elongation at break up to 12% depending upon the exact repeating unit structure.

Transport properties of a polyimide solvent resistant nanofiltration membrane

A series of solvent resistant polyimide membranes, with nominal molecular weight cut-offs (MWCO) between 230–700 Da, are evaluated through high pressure filtration of six solutes dissolved in toluene. These solutes range in MW from 142 to 311 Da, and include normal and branched alkanes, and aromatic compounds. The asymmetric membranes, made from a copolymer of benzophenone tetracarboxylic acid with toluene diisocyanate and methylene bis(phenyl isocyanate), shows preferential transport of straight chain over branched alkanes, and of aromatic over non-aromatic compounds. The normal alkanes allow for estimation of MWCO. Performance curves are generated for this family of polyimide membranes. Transport rates, in mm/h, are determined for each dissolved component based on a solution–diffusion equation. These rates are then used to predict membrane performance under alternative conditions of pressure and composition. The results are consistent over the whole range of MWCO’s with the membranes acting in a solution–diffusion mode. These membranes have industrial utility in the enrichment of aromatic streams and in nanofiltration applications.

Phosphorus‐containing epoxy resins: Thermal characterization

AbstractThree 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

Synthesis and properties of fluorinated polyimides. 1. Derived from novel 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl

AbstractA new diamine monomer, 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl (ATFT) was synthesized that led to a number of novel fluorinated polyimides by solution as well as thermal imidization routes when reacted with different commercially available dianhydrides like pyromellatic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), or 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane (6FDA). The polyimides ATFT/BTDA and ATFT/6FDA derived from both routes were soluble in several organic solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide, and dimethyl sulfoxide. The polyimide ATFT/PMDA was only soluble in N‐methylpyrollidone. The polyimide films had low water absorption of 0.3–0.7%, low dielectric constants of 2.72–3.3 at 1 Hz, refractive indices of 1.594–1.647 at 589.3 nm, and optical transparency >85%. These polyimides showed very high thermal stability with decomposition temperatures (5% weight loss) up to 532 °C in air and good isothermal stability; only 7% weight loss occurred at 400 °C after 7 h, and less than 0.6% weight loss was observed at 315 °C for 5 h. Transparent thin films of these polyimides exhibited tensile strengths up to 112 MPa, a modulus of elasticity up to 3.05 GPa, and elongation at break up to 21% depending on the repeating unit structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1016–1027, 2002

Preparation and structure of polyimides derived from H complexes of benzophenonetetracarboxylic acid with diaminodiphenyl ether

The possibility of using H complexes of dialkyl dihydrogen 3,3',4,4'-benzophenonetetracarboxylates and 4,4'-diaminodiphenyl ether and of polyimides prepared therefrom as polyimide foam materials, carbon-reinforced plastics, and foam composites was examined.

Addition Polyimides from Non-Mutagenic Diamines

Studies were conducted to find an acceptable non-mutagenic diamine to replace 4,4′-methylenedianiline (MDA), a suspect carcinogen, which is currently being used in PMR-15 polyimide applications. Several diamines containing fluorine and trifluoromethyl substituent groups were synthesized. The diamines were polymerized with the dimethyl ester of 3,3′,4,4′ -benzophenonetetracarboxylic acid (BTDE), using the monomethyl ester of nadic acid (NE) as an endcap. The effect of diamine structure on rheological properties, glass transition temperature, and thermo-oxidative stability was investigated. Unidirectional laminates were fabricated from selected resins, using carbon fibre as the reinforcement. The results indicate that some of the diamines containing trifluoromethyl groups are non-mutagenic, and have potential to replace MDA in PMR polyimides for long-term applications at temperatures up to 300 °C.

Reflective and conductive silvered polyimide films for space applications prepared via a novel single-stage self-metallization technique

Highly reflective and surface conductive flexible polyimide films have been prepared by the incorporation of silver(I) acetate and 1,1,1-trifluoro-2,4-pentanedione into a dimethylacetamide solution of poly(amic acid), formed from 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride and 4,4′-oxydianiline. Thermal curing of the silver(I)-containing poly(amic acid) leads to cycloimidization of the polyimide precursor with concomitant silver(I) reduction yielding a reflective and conductive silvered surface with properties approaching those of the native metal. Ligand/anion effects on the metallization process resulted when using additional silver(I) compounds including: silver(I) nitrate; silver(I) tetrafluoroborate; (trifluoroacetato)silver(I); (hexafluoroacetylacetonato)silver(I); (trifluoroacetylacetonato)silver(I); and 1-(2-thienyl)-3,3,3(trifluoroacetonato)silver(I). Comparisons among these six silver(I) compounds as precursors for the surface metallization of BTDA/4,4′–ODA are discussed with regard to reflectivity, conductivity and surface morphology. The metallized films usually retain the essential mechanical properties and thermal properties of a parent film. Films were characterized by X-ray diffraction, transmission and scanning electron microscopy, tapping mode atomic force microscopy and X-ray photoelectron spectroscopy. Also, electrical conductivity, reflectivity, differential scanning calorimetric, thermal gravimetric and mechanical measurements were made on the metallized films.

Structural and Thermal Characterisation of Nadimide Resins

A series of hexachloronadimides containing phosphine oxide in the backbone were synthesized by the reaction of bis(3-amino phenyl) methyl phosphine oxide (BAP) with pyromellitic dianhydride (PMDA)/3,3’,4,4’-benzophenone tetracarboxylic acid dianhydride (BTDA)/2,2-bis(3,4-dicarboxy phenyl) hexafluoropropane dianhydride (6F) and hexachloronadic anhydride in glacial acetic acid/acetone.

Magnetic-field effect on the micellar surface-bound benzophenone tetracarboxylic acid–sodium salt in aqueous cetyltrimethylammonium bromide medium

The effect of an external magnetic field on the spin evolution of the radical pair (RP) photo-generated from the micellar surface-bound benzophenone tetracarboxylic acid sodium salt (BPD) and cetyltrimethylammonium bromide (CTAB) by H-abstraction has been investigated. BPD in SDS or TX100 micellar media does not exhibit any MFE but, in CTAB micellar medium, the RP decay rate and the yield of escape radicals gradually increase with increasing field and ultimately reach saturation. The magnetic field dependence of escape yields and decay rates are systematised in terms of the relaxation mechanism due to anisotropic HFI [ δ(hfi)]. At high fields, however, a saturation in the MFE is observed which has been ascribed to the predominance of the escape process.

Synthesis of surface-metallized polymeric films by in situ reduction of (4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionato) silver(I) in a polyimide matrix

Thermal curing of the (4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionato)silver(I)-containing poly(amic acid) formed from 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA) and 4,4′-oxydianiline (4,4′-ODA) in dimethylacetamide gives both polyimide films via cyclodehydration and reduction of silver(I) to the native metal. Silver(0) migrates to the surface resulting in surface metallized composite films, which can have excellent reflectivity, but do not exhibit surface electrical conductivity. The films retain mechanical and thermal properties similar to those of the parent polyimide. X-ray diffraction shows crystalline face-centered-cubic silver in the films after thermal curing. Microscopy data show that the surface particle sizes are in the range of approximately 50–100 nm. Significant silver remains in the bulk of the polyimide film with varying particles sizes generally less than approximately 15 nm. The interior of the metallized films is not electrically conducting. Films were characterized by x-ray diffraction, differential scanning calorimetry, thermal gravimetric analysis, x-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, and mechanical measurements.

Inverse Chemical Vapor Deposition: A Novel Single Stage Synthesis of Highly Reflective and Conductive Silvered Polymeric Films

Highly reflective and surface conductive flexible polyimide films have been prepared by the incorporation of silver(I) acetate and 1,1,1-trifluoro-2,4-pentanedione into a dimethylacetamide solution of the poly(amic acid) formed from 3,3‘,4,4‘-benzophenone tetracarboxylic acid dianhydride and 4,4‘-oxydianiline. Thermal curing of the silver(I)-containing poly(amic acid) leads to cycloimidization of the polyimide precursor with concomitant silver(I) reduction, yielding a reflective and conductive silver surface approaching that of the native metal. The metalized films retain the essential mechanical and thermal properties of the parent film. Films were characterized by X-ray diffraction, transmission and scanning electron microscopy, tapping mode atomic force microscopy, X-ray photoelectron spectroscopy, and conductivity, reflectivity, thermal, and mechanical measurements.

Synthesis of Surface-Metallized Polyimide Films via in Situ Reduction of (Perfluoroalkanoato)silver(I) Complexes in a Poly(amic acid) Precursor

Thermal curing of the silver(I)-containing poly(amic acid) formed from 3,3‘,4,4‘-benzophenone tetracarboxylic acid dianhydride (BTDA) and 4,4‘-oxydianiline (4,4‘-ODA) in dimethylacetamide leads both to polyimide films via cyclodehydration and to reduction of silver(I) giving a metallized surface. The resulting metallized composite films retain mechanical and thermal properties similar to those of the parent polyimide. Variation of the silver(I) additive and concentration and the thermal cure cycle allows the fabrication of silver layers which are both reflective and/or electrically conductive. Silver(I) trifluoroacetate and pentafluoropropanoate give excellent silvered films; however, higher perfluoroalkanoates such as silver(I) heptafluorobutanoate give films which are poorly surface metallized and extensively bubbled. X-ray diffraction shows crystalline face-centered cubic silver in the films after thermal curing. Microscopy data show that the surface particle sizes are in the range of ca. 100−500 nm. S...

High-pressure synthesis and properties of aliphatic-aromatic polyimides via nylon-salt-type monomers derived from aliphatic diamines and benzophenonetetracarboxylic acid

Aliphatic polyimides (P-XBTA) having inherent viscosities of 0.4–1.4 dL/g were readily synthesized by the high-pressure polycondensation of the salt monomers, composed of aliphatic diamines having various methylene chain lengths (X = 4–12) and 3,3′,4,4′-benzophenonetetracarboxylic acid (BTA), under 200–250 MPa at 200–320°C. The salt monomers with odd-numbered methylene units were found to be more susceptible to crosslinking than those containing even-numbered methylene chains. The polyimides having even-numbered methylene units were highly crystalline, whereas those with odd-numbered methylene chains were crosslinked and therefore amorphous with only one exception, i.e., P-11BTA. The thermal behavior of these polymers was also studied. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 39–47, 1998

Thermal behaviour of ethynyl and ethenyl terminated imide resins

A series of ethynyl and ethenyl end-capped imide resins were synthesised by the reaction of 9,9-bis(4-aminophenyl) fluorene (BAF) with pyromellitic dianhydride (PMDA)3/3′, 4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA)/2,2-bis(3,4-dicarboxy phenyl) hexafluoropropane dianhydride (6F) and 3-ethynyl aniline/maleic anhydride. Structural characterisation was done by infra red and elemental analysis. Thermal characterisation was done by differential scanning calorimetry and thermogravimetric analysis. The decomposition temperatures of cured resins were above 200°C in nitrogen atmosphere. Char yield at 800°C ranged from 59–65.5%.

Highly Reflective and Surface Conductive Silver-Polyimide Films Fabricated Via Reduction of Silver(I) in a Thermally Curing Poly(Amic Acid) Matrix

AbstractHighly reflective and surface conductive silvered polyimide films have been prepared by the incorporation of the (1,1,1-trifluoro-2,4-pentanedionato)silver(I) complex into a dimethylacetamide solution of the poly(amic acid) formed from 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA) and 4,4'-oxydianiline (ODA). Thermal curing of the silver(I)- containing poly(amic acid) films leads to cycloimidization with concomitant silver(I) reduction yielding a reflective and conductive silvered film surface.