Pyromellitic Dianhydride Research Articles

Improving the flame‐retardant property of bottle‐grade PET foam made by reactive foam extrusion

AbstractUpcycling of low intrinsic viscosity (IV) poly(ethylene terephthalate) (PET) grades, such as bottle‐ or recycled grades, by a reactive foam extrusion process, provides an appropriate alternative to high pricing, high IV grades commonly used for foaming applications. However, the drawback of bottle‐grade PET foams is its flame retardant (FR) performance. In this study, pyromellitic dianhydride was used as a chain extender to foam bottle‐grade PET. The influence of different FRs, containing halogenated (HFR) and four different phosphorous‐based types, on the processability and final foam properties was investigated. HFR showed better processability to achieve proper foams with fine morphology compared to P‐based FRs, where the FR content was adjusted between 2 and 5 wt%. However, HFR exhibited lower FR performance by cone calorimeter testing compared to the P‐based FRs and the commercial reference foam Kerdyn. Nonetheless, all of the FRs can only improve the time to ignition of the neat PET foams while the other values depend on the specific type of FR. In addition, all FR foams have improved mechanical properties more than twice in comparison to the neat PET foam.

Effect of MWCNTs’ Content on the Properties of Polyimide Composite Molding Materials

A series of MWCNTs/PI composite molding powders with different MWCNTs contents were prepared by ultrasonic dispersion in situ polymerization and blending method, and the samples were prepared by molding. In this experiment, 3, 3’, 4, 4’ - biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA) and 4, 4’ - diaminodiphenyl ether (ODA) are taken as the main raw materials and MWCNTs as reinforcement materials. The molecular structure, thermal stability, mechanical properties, wear resistance and hardness of the composites were characterized. Results showed that mechanical properties of the composite molding materials prepared by ultrasonic dispersion in situ polymerization are better than those prepared by dry mixing method. The composite molding materials showed the best properties at the MWCNTs content of 0.5wt%. What’s more, the tensile strength and elongation at break are 108.9MPa and 4.5%, which are 26% and 23.6% higher than those of pure PI.

Study on Molding Process of Ether Anhydride Type Polyimide Materials

The main molding process of ether anhydride type polyimide materials which synthesized by the main meterials of pyromellitic dianhydride (PMDA), 3, 3’, 4, 4’-tetracarboxydiphthalic dianhydride (OPDA) and Diamine diphenyl ether (ODA) was researched. The effects of molding temperature, molding time and molding pressure on the tensile properties of molded products were investigated. And the effects of dianhydride ratio on the properties and molding process of ether anhydr ide type polyimide materials was discussed. Results showed that samples molded by polyimide molding powder appeared the best comprehensive performance when the molar ratio of PMDA and OPDA was 2:1, with the tensile strength of 93.5 MPa, the elongation at break of 10.1%, the vitrification transition temperature of 340 °C and the thermal decomposition temperature of 5% was 574 °C. And molding process is under that the molding temperature is 410°C, the molding pressure is 4.0Mpa and the molding time is 15min.

Toward Improved Optical Transparency of Polyimide Aerogels.

Highly translucent polyimide aerogels were prepared by combining equimolar amounts of pyromellitic dianhydride, 4,4'-hexafluoroisopropylidene di(phthalic anhydride) (6FDA), and 2,2'-dimethylbenzidine and cross-linking with 1,3,5-benzenetricarbonyl trichloride. A multivariable statistical design of experiments was used to perform a comparison study between three variables used to fabricate the aerogels: formulated repeat unit (n) of polyimide oligomers, 6FDA fraction of total dianhydride (0-50 mol %), and total polymer concentration in solution (7-10 wt %). Polymers with 25 mol % 6FDA in the backbone structure were found to produce polyimide aerogels with high optical transmission and low haze. These aerogels also possessed higher surface areas and very narrow nanoscale pore size distribution. Because of the decreased thermal conductivity with increasing amount of 6FDA in the backbone, these aerogels may find use where the combination of high optical transparency and thermal impedance is desired, such as insulated window panes. To this end, future efforts will focus on reducing the yellow color of the polyimide aerogels.

Characterisation of Romakon™-PM pervaporation membranes for the separation of dilute aqueous alcohol mixtures

Thin-film composite pervaporation membranes with selective layer from pyromellitic dianhydride -4,4′ oxydianiline polyimide on porous poly(amide-imide) support (Romakon™-PM) for treatment of water/ethanol mixtures with exceeding water content (>50 wt% water) are characterised by the use of scanning electron microscopy, atomic force microscopy and X-ray diffraction. Membranes showed high values of flux, separation factor and PSI (up to 774) in the selected feed mixture composition range. The influence of the support and structural features of the polyimide in the coating layer on the transport properties is discussed. The membranes are successfully tested in terms of pervaporation dehydration of beer. The influence of the permeate temperature on the separation process performance is discussed.

Effect of Aliphatic and Aromatic Chain Extenders on Thermal Stability of Graphene Oxide/Polyurethane Hybrid Composites Prepared by Sol‐Gel Method

AbstractHybrid composites of graphene and polyurethane (PU) were prepared via sol‐gel method. The isocyanate‐terminated PUs with chain extenders of pyromellitic dianhydride (PMDA) and butanediol were reacted with (3‐aminopropyl) triethoxysilane (APTES) to obtain Polyurethane with PMDA chain extender (PUI) and Polyurethane with BD chain extender (PUBD), respectively. Sol‐gel reaction between the silane‐modified polyurethanes with APTES‐modified graphene oxide resulted in the hybrid composites with high thermal degradation temperature and char content. Results of Fourier‐transform infrared spectroscopy and proton nuclear magnetic resonance analysis confirmed chemical modification of graphene and successful preparation of the bifunctional silane‐modified PUI and PUBD, respectively. Based on the thermogravimetric analysis (TGA) results, PMDA chain extender resulted in higher degradation temperature and char content in the hybrid composites. In addition, siloxane networks formed by sol‐gel process resulted in synergistic effects on improving thermal stability of the PU materials. X‐ray diffraction results in addition to the scanning and transmission electron microscopy images confirmed successful oxidation of graphite and also its modification process.

Binary/ternary memory behavior of organo-solubility polyimides containing flexible imide linkages and pendent triphenylamine or 3, 4, 5-trifluobenzene moieties

Two different aromatic diamines monomers (3, 5-diamino-N-(4'-phenyl-4''-triphenylamino)-N-(4''-benzyl-4'''-triphenylamino)benzamide (DPTBTB) and 3, 5-diamino-N-(4'-3'', 4'', 5''-trifluorobiphenyl)-N-(4''-benzyl-3''', 4''', 5'''-trifluorophenyl)benzamide (DTBTB)) containing flexible linkages were designed and synthesized, respectively. Four organo-solubility polyimides (PI-a, PI-b, PI-c, and PI-d) were prepared via a two-step procedure with pyromellitic dianhydride (PMDA) and 3, 3', 4, 4'-biphenyltetracarboxylic dianhydride (BPDA), respectively. The four PIs performed excellent thermal stability with the temperature of 5% weight loss in range of 370–420 ℃ at N2 atmosphere. The Al/PI-a/ITO and Al/PI-b/ITO memory devices exhibited binary write-once-many-read (WORM) and rewritable (Flash) behavior, respectively. But the Al/PI-c/ITO and Al/PI-d/ITO memory devices showed ternary WORM and Flash behavior due to the deeper charge traps came from the fluorinated groups in the structure of PI-c and PI-d, respectively. The memory switching mechanism could be demonstrated through molecular simulation. The results gave an effective strategy that adjusting the structure of PI to achieve different memory effects.

Synthesis and gas permeation properties of thermally rearranged poly(ether-benzoxazole)s with low rearrangement temperatures.

The diamine monomer, 9,9-bis[4-(4-amino-3-hydroxylphenoxy)phenyl] fluorene (bis-AHPPF) was successfully synthesized according to our modified method. A series of hydroxyl-containing poly(ether-imide)s (HPEIs) were prepared by polycondensation of the bis-AHPPF diamine with six kinds of dianhydrides, including 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), pyromellitic dianhydride (PMDA), 3,3′,4,4′-biphenyl tetracarboxylic diandhydride (BPDA), 3,3′,4,4′-oxydiphthalic anhydride (ODPA), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and 4,4′-(hexafluoroisopropylidine)diphtalic anhydride (6FDA) followed by thermal imidization. The corresponding thermally rearranged (TR) membranes were obtained by solid state thermal treatment at high temperature under a nitrogen atmosphere. The chemical structure, and physical, thermal and mechanical properties of the HPEI precursors were characterized. The effects of heat treatment temperature and dianhydrides on the gas transport properties of the poly(ether-benzoxazole) (PEBO) membranes were also investigated. It was found that these HPEIs showed excellent thermal and mechanical properties. All the HPEI precursors underwent thermal conversion in a N2 atmosphere with low rearrangement temperatures. The gas permeabilities of the PEBO membranes increased with the increase of thermal treatment temperature. When HPEI–6FDA was treated at 450 °C for 1 h, the H2, CO2, O2 and N2 permeabilities of the membrane reached 239.6, 196.04, 46.41 and 9.25 Barrers coupled with a O2/N2 selectivity of 5.02 and a CO2/N2 selectivity of 21.19. In six TR-PEBOs, PEBO–6FDA exhibited the lowest rearrangement temperature and largest gas permeabilities. Therefore, thermally rearranged membranes from bis-AHPPF-based HPEIs are expected to be promising materials for gas separation.

Crystallization and biocompatibility enhancement of 3D-printed poly(l-lactide) vascular stents with long chain branching structures

The long chain branching poly(L-lactide)s were prepared by reactive processing of linear PLA using pyromellitic dianhydride and polyfunctional epoxy ether as the branching agent and their vascular stents were fabricated via 3D-printing.

Electrospinning of Aqueous Solutions of a Triethylammonium Salt of Polyamic Acid and Properties of the Nonwoven Polyimide Materials

The electrospinning conditions of aqueous and aqueous-alcoholic solutions of the triethylammonium salt of a polyamic acid derived from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether in the concentration interval 8–15 wt % were studied comprehensively. The best operation characteristics of the nonwoven materials are reached when forming the fibers from a 10% solution of the prepolymer in a 70/30 wt % alcohol/water mixture at the reaction mixture viscosity in the interval 0.27–0.96 Pa s and the surface tension of 26 mN m−1. The dynamics of thermal imidization of the nonwoven material based on the triethylammonium salt polyamic acid was monitored by IR spectroscopy; it was found that the imide ring formation was complete at 200°C. Samples of the nonwoven polyimide material were obtained, and their deformation, strength, and thermal properties were determined.

Improved photoremoval performance of boron carbon nitride–pyromellitic dianhydride composite toward tetracycline and Cr(vi) by itself to change the solution pH

A series of boron carbon nitride–pyromellitic dianhydride (BCNPA) composites were successfully synthesized for the first time, where BCNPA3 exhibited the best adsorption and photodegradation performances for tetracycline (TC) under visible-light irradiation.

A promising drug delivery candidate (CS-g-PMDA-CYS-fused gold nanoparticles) for inhibition of multidrug-resistant uropathogenic Serratia marcescens

Antibiotic resistance amongst microbial pathogens is a mounting serious issue in researchers and physicians. Various alternatives to overcome the multidrug-resistant bacterial infections are under search, and biofilm growth inhibition is one of them. In this investigation, a polymeric drug delivery system loaded with multi-serratial drugs to improve the delivery of drugs against urinary tract infection causative Serratia marcescens. The chitosan grafted pyromellitic dianhydride – cysteine (CS-g-PMDA-CYS) was conjugated with AuNPs by using the –SH group of CYS and RF (rifampicin) and INH (isoniazid) were loaded in AuNPs-fused CS-g-PMDA-CYS system. Several physicochemical techniques characterized this fabricated AuNPs/RF/INH/CS-g-PMDA-CYS system. The successful encapsulation of RF and INH in AuNPs-fused CS-g-PMDA-CYS polymer had confirmed, and it observed the loading capacity for RF and INH was 9.02% and 13.12%, respectively. The in vitro drug discharge pattern was perceived high in pH 5.5 compared with pH 7.4. The AuNPs/RF/INH/CS-g-PMDA-CYS escalates 74% of Caenorhabditis elegans survival during Serratia marcescens infection by aiming biofilm development and virulence in S. marcescens. Author postulate that the fabricated system is a promising drug carrier and delivery system for inhibition of multidrug-resistant bacterias like S. marcescens.

Adsorption of Pb(II) from Aqueous Solution by Mercerized Moso Bamboo Chemically Modified with Pyromellitic Dianhydride

AbstractA novel adsorbent of chemically modified moso bamboo (CMMB) for removing Pb(II) from an aqueous solution was prepared from twice-mercerized moso bamboo (MMB) using pyromellitic dianhydride ...

Effect of Two‐Step Chain Extension using Joncryl and PMDA on the Rheological Properties of Poly (lactic acid)

AbstractThis research considers a two‐step chain extension reaction in the presence of two chain extenders, Joncryl and Pyromellitic dianhydride (PMDA), as a solution for poor melt properties of poly (lactic acid) (PLA). The aim of adding PMDA is to increase the carboxyl groups via the anhydride ring‐opening reaction so that the reaction between PLA and Joncryl could be facilitated since the reactivity between the epoxy and carboxyl group is more than epoxy and hydroxyl group. The reactions are confirmed by measuring the acid value, and a two‐step reaction mechanism is suggested. Shear and elongational rheological properties of the samples are investigated; furthermore, gel permeation chromatography analyses and tensile tests are exploited for studying the molecular weight and tensile properties, respectively. The results show that the chain extension reactions lead to an increase in the storage modulus, complex viscosity, and molecular weight. Also, the PLA chains which are extended utilizing both chain extenders simultaneously evince a synergistic improvement in the shear and elongational rheological properties due to longer segments between branching points on the structure.

Thermal Expansion Behavior of Poly(amide-imide) Films with Ultrahigh Tensile Strength and Ultralow CTE

A series of novel poly(amide-imide) (PAI) films with different amide contents were prepared from pyromellitic dianhydride and four amide-containing diamines. These PAI films exhibited excellent mechanical and thermal properties with tensile strength of 203.7–297.4 MPa and Tg above 407 °C. The rigid backbone structures combined with strong intermolecular interactions provided PAI films with ultralow in-plane CTE values from −4.17 ppm/°C to −0.39 ppm/°C in the temperature range of 30–300 °C. The correlation between thermal expansion behavior and aggregation structures of PAI film was investigated. The results suggested that hydrogen bonding interactions could be maintained even at high temperature, thus resulting in good dimension reversibility of films in multiple heating-cooling cycles. It is demonstrated that dimensional stabilities of PAI films are determined by the rigidity, orientation, and packing of molecular chains. Heat-resistant PAI films with ultralow CTE can be developed as flexible substrates by regulating backbones and aggregation structures for optoelectronic application.

Rich nitrogen-doped ordered mesoporous carbon synthesized by copolymerization of PMDA and ODA with SBA-15 as a template for high-performance supercapacitors

Polyimide-based nitrogen-doped ordered mesoporous carbon was successfully synthesised utilising SBA-15 as a hard template. By controlling the molar ratio of 4,4′-oxydianiline to pyromellitic dianhydride during copolymerising and carbonisation, nitrogen-doped ordered mesoporous carbon (NOMCx) with various nitrogen content and pore distribution were obtained. When the molar ratio of 4,4′-oxydianiline to pyromellitic dianhydride was 6, NOMC6 presented the highest content of nitrogen (7.94 wt%) and moderate specific surface area (890 m2 g−1). Accordingly, NOMC6 showed a high specific capacitance of 282 F g−1 at 0.1 A g−1, and excellent cycle stability (no capacitance loss over 10,000 cycles) in 1 M H2SO4. The synthesised ordered mesoporous carbons do not show a significant decrease of capacitive performance in the current density range of 2 to 20 A g−1. Furthermore, a symmetrical supercapacitor consisting of two NOMC6 electrodes exhibited an energy density of 4.77 Wh kg−1 at power density of 500 W kg−1 (1 A g−1).

Synthesis and Antimicrobial Screening of Novel Azetidin-2-ones Derived from Pyromellitic Diimide via [2+2]-Cycloaddition Reaction

A series of novel 2-azetidinone derivatives have been obtained starting from pyromellitic dianhydride. Pyromellitic dianhydride was converted to pyromellitic diimide using sodium cyanate, and the diimide was alkylated with ethyl chloroacetate. The resulting diester was treated with hydrazine hydrate to obtain dihydrazide which reacted with substituted pyridine-2-carbaldehydes to give the corresponding Schiff bases, and [2+2]-cycloaddition of the latter with chloroacetyl chloride in the presence of triethylamine afforded the target azetidin-2-one derivatives. The newly synthesized compounds showed high antimicrobial activities against some bacterial and fungal strains.

Synthesis and characterization of branched polyether ester urethanes/organo-clay nanocomposites

Flame retardant branched polyether ester urethanes were prepared by reacting phosphorous based polyether ester polyol with three different types of diisocyanates like IPDI, HMDI, and TDI. Branched polyether ester polyol has been synthesized through ring-opening of pyromellitic dianhydride followed by esterification. This prepared branched polyol was used for the preparation of branched polyurethanes through condensation polymerization. Modification of Na-MMT clay is done to improve the interlayer distance between two silicates sheets for the preparation of BPEEU nanocomposite through the intercalation method. The interlayer distance of clay after modification was increased by 3.78 Ao, which was measured using XRD. Morphological study shows an addition of 3% O-MMT clay gives excellent properties whereas the addition of 5% clay in polymer matrix increases aggregation and brittleness of branched polyurethanes which results in failure of coating and casting. The addition of clay increases thermal stability by 30–4p0%. The hardness and tensile strength of neat BPEEUs increased with the addition of 3% O-MMT clay in BPEEUs. Flame retardant property of branched polyurethanes nanocomposites shows that clay particle does not have any impact on the flammability of polymer. Branched polyurethanes show excellent chemical and solvent resistance properties due to the presence of the high number of polypropylene in the molecular structure.

Investigation of the reactivity of 4-amino-5-hydrazineyl-4H-1,2, 4-triazole-3-thiol towards some selected carbonyl compounds: synthesis of novel triazolotriazine-, triazolotetrazine-, and triazolopthalazine derivatives

Abstract The reactivity of 4-amino-5-hydrazineyl-4H-1,2,4-triazole-3-thiol (1) towards several carbonyl compounds was investigated. We have found that on treatment of 1 with isatoic anhydride (2), 1,8-naphthalic anhydride (4), diphenic anhydride (6), pyromellitic dianhydride (8), and tetrabromophthalic anhydride (10), the reaction proceeds to give triazolotetrazine- and triazolophthalazine derivatives in good yields using simple experimental procedures. The structure of the synthesized compounds was confirmed using different spectroscopic data (1H NMR, 13C NMR, mass spectrometry, and elemental analysis). The mechanism of the obtained products was also discussed.

Polycondensation depressor additives for oil products using higher fat alcohols

There are polycondensation ester depressant additives, obtained by the condensation of polyhydric alcohols, synthetic fatty acids and dicarboxylic acids. The effectiveness of such additives is limited to oils and petroleum products containing high melting solid hydrocarbons. Such additives are not effective in diesel fuels. Therefore, it was of interest to synthesize condensation ester depressor additives with a different combination of starting materials. We used pyromellitic dianhydride (it is a product derived from polyhydric acid) as a base, also higher fatty alcohols as substances that add additives to the surface-active properties and solubility in oils and petroleum products, and glycols, for example ethylene glycol, as substances that regulate the molecular weight of additives. Depressor additives were synthesized by condensation of higher fatty alcohols fractions C10 – C20 and pyromellitic dianhydride with the subsequent introduction of ethylene glycol into the structure of additives. We evaluated the depressor properties of the additives when they were introduced into the diesel component of the Surgut condensate stabilization plant. Additives were considered all the more effective, the higher the depression of the pour point of the oil in their presence and the lower their consumption. We introduced into the diesel component of the Surgut condensate stabilization plant, and then evaluated their properties. The higher the depression of the pour point of the oil when using depressor additives and the lower their consumption, the additives were considered more effective. Taking into account the simplicity of the technology, waste-free production and sufficiently high efficiency, we can recommend the depressor additives synthesized in the study to reduce the solidification temperature of diesel fuels.