Category: 18959-30-3

Chemistry is traditionally divided into organic and inorganic chemistry. Quality Control of 4,5-Difluorophthalic Anhydride, The former is the study of compounds containing at least one carbon-hydrogen bonds.In a patent，Which mentioned a new discovery about 18959-30-3

The structural changes and tribological performance of thermosetting polyimide were investigated by electron, proton or both combined irradiations at 25. keV in a ground-based simulation facility. Three forms of irradiations could lead to the formation of the carbonized layer on the polymer surface that could increase the hardness and adhesive force of the material. Proton irradiation induced more extensive changes in structure and friction behavior than electron irradiation by reason of the higher linear energy transfer value, and combined irradiation resulted in the largest impact, but which was less than the sum of the radiation effects of electron and proton. Moreover, the experimental results indicated that the changes in friction behavior are closely related with the carbonized layer, which was easily worn out in friction process and could introduce a shift from adhesion wear to three-body abrasive wear that reduced the wear rate and the friction coefficient. The friction process of irradiated samples could be divided into the initial stage and the steady stage. Three forms of irradiations all induced the high friction coefficient in the initial stage and the low friction coefficient in the steady stage, and the wear rate of the irradiated samples decreased in the order: electron irradiation>proton irradiation>combined irradiation.

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Reference：
Benzofuran – Wikipedia,
Benzofuran | C8H2954O – PubChem

Related Products of 18959-30-3, Catalysts function by providing an alternate reaction mechanism that has a lower activation energy than would be found in the absence of the catalyst. In some cases, the catalyzed mechanism may include additional steps.In a article, 18959-30-3, molcular formula is C8H2F2O3, introducing its new discovery.

Three kinds of aromatic poly(amic acid)s that contain acetylene groups in the main chain were cured in air at temperatures up to 400C to give intermolecular crosslinked polyimides. The crosslink reactions occurred at the internal acetylene units and the chemical structures thus generated have been investigated by thermal analyses (thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC)) and high resolution solid-state 13C cross polarization (CP)/magic angle spinning (MAS) NMR. The thermal analyses indicated that broad exotherms are observed above 300C for all the polyimides cured at 200, 300, and 350C, and the exothermal reactions do not eliminate volatile components from the polyimide structure. The 13C CP/MAS NMR spectra of pyromellitic dianhydride/3,3?-diaminodiphenyl-acetylene (PMDA/m-intA) polyimides show that the signal intensities of the acetylene carbons and the phenyl carbons directly bonded to the acetylene units significantly decrease after curing above 300C, which indicates that crosslink reactions occurred during curing. In addition, a signal that can be assigned to the C1-carbon of biphenyl structure newly appears after curing, and it grows as the curing temperature increases from 350 to 400C. From the examination of the chemical shift of the new signal, the most probable crosslink mechanism is the Diels-Alder cycloaddition that occurs between two phenylethynyl groups and provides polycyclic aromatic structures containing biphenyl linkages. The DSC, TGA, and NMR spectra suggest that the same crosslink reactions occur in the other two polyimides, although they occur in the different temperatures ranges. The signal intensities in the NMR spectra indicate that 40-55% of the acetylene carbons remained unreacted even after curing at 400C. This situation significantly differs from the cases of acetylene- and phenylethynyl-terminated polyimides, in which almost no acetylene units remained after curing as a result of a variety of crosslink reactions. The crosslink reactions occurring at the internal acetylene units are more selective and uniform due to the preferred layer packing of the diphenylacetylene groups and the restricted molecular motion in the solid state.

The proportionality constant is the rate constant for the particular unimolecular reaction. the reaction rate is directly proportional to the concentration of the reactant. I hope my blog about 18959-30-3 is helpful to your research. Related Products of 18959-30-3

Reference：
Benzofuran – Wikipedia,
Benzofuran | C8H2958O – PubChem

In heterogeneous catalysis, the catalyst is in a different phase from the reactants. Product Details of 18959-30-3, At least one of the reactants interacts with the solid surface in a physical process called adsorption in such a way. 18959-30-3, name is 4,5-Difluorophthalic Anhydride. In an article，Which mentioned a new discovery about 18959-30-3

A series of thermosetting polyimide oligomers with different diamines (isomers) and same calculated number-average molecular weights (Mn) were synthesized with BPDA (biphenyl-tetracarboxylic acid dianhydride), 4,4?-ODA (4,4?-oxydianiline), 3,4?-ODA (3,4?-oxydianiline) and 4-PEPA (4-phenylethynylphthalic anhydride). Herein, we investigate the effect of monomer configuration on the mechanical, thermal and tribological properties of thermosetting polyimides. Experimental results demonstrate the relationship between molecular configuration and mechanical, thermal and tribological properties. It is revealed that as the content of 4,4?-ODA increases, Tg, Young’s modulus and hardness increases and coefficient of friction (COF) and wear rate (WR) decrease under most conditions. Compared with variations of COFs and WRs of TPIs to velocity or load, it is easy to confirm the major influencing factor under different conditions.

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Reference：
Benzofuran – Wikipedia,
Benzofuran | C8H2972O – PubChem

In heterogeneous catalysis, the catalyst is in a different phase from the reactants. Safety of 4,5-Difluorophthalic Anhydride, At least one of the reactants interacts with the solid surface in a physical process called adsorption in such a way. 18959-30-3, name is 4,5-Difluorophthalic Anhydride. In an article，Which mentioned a new discovery about 18959-30-3

Most of the existing polyimide oligomers for resin transfer molding (RTM) processing exhibited high melt viscosity, which can only maintain below 1 Pa·s at 280C for 2 h, leading to very high process temperatures. So novel RTM-type oligomers with lower and stable melt viscosities are more desirable. Three series of thermoset oligoimides derived from 1,4-bis(3,4-dicarboxy phenoxy)benzene dianhydride and three different aromatic diamines were prepared herein. The diamines included 4,4?-oxydianiline, 2,2?-bis(trifluoromethyl)benzidine (TFDB), and 2-phenyl-4,4?-diaminodiphenyl ether (p-ODA). 4-Phenylethynylphthalic anhydride was used as an endcapping reagent. Effects of the chemical structures and molecular weights of the oligoimides on their aggregated structures, melt processability, and the thermal and mechanical properties of the cured films were then systematically investigated. X-Ray diffraction results indicated that ODA series oligoimides and TFDB series oligoimides showed crystallinity in various degrees. However, the asymmetric p-ODA enables the p-ODA series oligoimides to exhibit amorphous forms. It was found that the p-ODA-based oligoimide with a molecular weight of 750 g mol?1 showed very low melt viscosity of 1 Pa·s even at 210C, and the melt viscosity could maintain below 1 Pa·s after isothermal aging for 2 h at any temperature in the range of 200?280C by rheological measurements. The cured film also showed a high glass transition temperature of 355C by dynamic mechanical analysis, very good thermal stability by thermogravimetric analysis, and good mechanical properties. It might be more suitable for RTM processes in the future.

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Reference：
Benzofuran – Wikipedia,
Benzofuran | C8H2971O – PubChem

One of the major reasons for studying chemical kinetics is to use measurements of the macroscopic properties of a system, name: 4,5-Difluorophthalic Anhydride, such as the rate of change in the concentration of reactants or products with time.In a article, mentioned the application of 18959-30-3, Name is 4,5-Difluorophthalic Anhydride, molecular formula is C8H2F2O3

The incorporation of 4-phenylethynylphthalic anhydride (4-PEPA) was utilized to synthesize a series of phenylethynyl terminated oligomers, according to different calculated number-average molecular weight (Mn). Modified polyetherimide (PEI) resins were prepared by the thermal curing reaction of phenylethynyl terminated etherimide oligomers. For comparison, unmodified PEI was also prepared. Thermal, macro- and micro-mechanical characterizations showed that the incorporation of phenylethynyl terminated agent resulted in a significant increase in glass transition temperature (Tg), tensile strength and microhardness. The tribological properties of PEI specimens were evaluated on a reciprocating friction and wear testing machine. Higher wear resistance was achieved by the incorporation of phenylethynyl terminated agent. Furthermore, wear rate of modified PEI prepared from the oligomers with the calculated Mn of 5000g/mol was about five times lower than that of unmodified PEI. At least for the range of this study, while increasing calculated Mn of oligomers, wear rate of modified PEI initially decreased sharply and then increased slightly. This is clearly related to the change in the macro- and micro-mechanical properties. Scanning electron microscope (SEM) observations of worn surfaces showed that type of wear changed from abrasive wear of unmodified PEI into fatigue wear.

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Reference：
Benzofuran – Wikipedia,
Benzofuran | C8H2937O – PubChem

One of the major reasons for studying chemical kinetics is to use measurements of the macroscopic properties of a system, Computed Properties of C8H2F2O3, such as the rate of change in the concentration of reactants or products with time.In a article, mentioned the application of 18959-30-3, Name is 4,5-Difluorophthalic Anhydride, molecular formula is C8H2F2O3

Multi-walled carbon nanotubes (MW-CNTs) were dispersed throughout a thermosetting polyimide Triple A PI (TriA-PI). TriA-PI is a newly developed phenylethynyl terminated polyimide, and exhibits excellent mechanical properties and processability with high glass transition temperature (Tg>300C). The resulting composites containing 3.3, 7.7, 14.3wt% MW-CNT exhibited relatively good dispersion in macroscopic scale. Tensile tests on the composites showed an increase in the elastic modulus and the yield strength, and decrease in the failure strain. Dynamic mechanical analysis (DMA) showed an increase in the glass transition temperature with incorporation of the carbon nanotubes. The experimental results suggested that the carbon nanotubes are acting as macroscopic crosslinks, and are further immobilizing the polyimide chains at elevated temperature.

Sometimes chemists are able to propose two or more mechanisms that are consistent with the available data. Computed Properties of C8H2F2O3, If a proposed mechanism predicts the wrong experimental rate law, however, the mechanism must be incorrect.Welcome to check out more blogs about 18959-30-3, in my other articles.

Reference：
Benzofuran – Wikipedia,
Benzofuran | C8H2959O – PubChem

In homogeneous catalysis, the catalyst is in the same phase as the reactant. The number of collisions between reactants and catalyst is at a maximum.In a patent, 18959-30-3, name is 4,5-Difluorophthalic Anhydride, introducing its new discovery. name: 4,5-Difluorophthalic Anhydride

As part of a program to develop high performance/high temperature adhesives and composite matrices for a Mach 2.4 high speed civil transport, imide oligomers containing phenylethynyl groups were investigated. Phenylethynyl groups were placed on the ends of oligomers of different molecular weights (1250, 2500 and 5000 g/mol), pendent along the backbone of oligomers and both pendent and terminal on oligomers. Many different compositions of phenylethynyl containing imide oligomers had been previously prepared and evaluated before selecting the composition based upon 3,3?,4,4?-biphenyltetracarboxcylic dianhydride (BPDA), 3,4?-oxydianiline (3,4?-ODA) and 1,3-bis(3-aminophenoxy)benzene (APB) for extensive work. 4-Phenylethynylphthalic anhydride (PEPA) was used to place phenylethynyl groups on the ends of the oligomers and 3,5-diamino-4?-phenylethynylbenzophenone (DPEB) was used to introduce pendent phenylethynyl groups along the oligomeric backbone. Upon heating above 300 C, the phenylethynyl groups react to provide chain extension, branching and cross-linking. Several of these materials exhibited excellent properties as adhesives and composite matrices. The chemistry, processability and properties of the oligomers, the cured polymers, bonded specimens and composites from phenylethynyl containing oligomers are presented. As part of a program to develop high performance/high temperature adhesives and composite matrices for a Mach 2.4 high speed civil transport, imide oligomers containing phenylethynyl groups were investigated. Phenylethynyl groups were placed on the ends of oligomers of different molecular weights (1250, 2500 and 5000 g/mol), pendent along the backbone of oligomers and both pendent and terminal on oligomers. Many different compositions of phenylethynyl containing imide oligomers had been previously prepared and evaluated before selecting the composition based upon 3,3′,4,4′-biphenyltetracarboxcylic dianhydride (BPDA), 3,4′-oxydianiline (3,4′-ODA) and 1,3-bis(3-aminophenoxy) benzene (APB) for extensive work. 4-Phenylethynylphthalic anhydride (PEPA) was used to place phenylethynyl groups on the ends of the oligomers and 3,5-diamino-4′-phenylethynylbenzophenone (DPEB) was used to introduce pendent phenylethynyl groups along the oligomeric backbone. Upon heating above 300C, the phenylethynyl groups react to provide chain extension, branching and cross-linking. Several of these materials exhibited excellent properties as adhesive and composite matrices. The chemistry, processability and properties of the oligomers, the cured polymers, bonded specimens and composites from phenylethynyl containing oligomers are presented. (C) 2000 Elsevier Science Ltd. All rights reserved.

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Reference：
Benzofuran – Wikipedia,
Benzofuran | C8H2934O – PubChem

Reference of 18959-30-3, Chemistry is the experimental science by definition. We want to make observations to prove hypothesis. For this purpose, we perform experiments in the lab. 18959-30-3, Name is 4,5-Difluorophthalic Anhydride,introducing its new discovery.

A relatively low-temperature crosslinking method for phenylethynyl (PE) end-capped oligomides was developed. PE end-capped oligomides are typically cured into crosslinked polyimides at 370 C for about 1 h. The addition of a low viscosity mixed-solvent of N-methylpyrrolidinone (NMP)Zdimethyl ether of polyethylene glycol (M = 250 g/mol), NMP/DM-PEG250, or NMP/polyethylene glycol (M = 400 g/mol), NMP/PEG400, as film forming medium for PE-end-capped oligomides was investigated. Fourier transform Infrared spectroscopy and 13C NMR showed that the mixed solvent addition was effective for achieving low-temperature crosslinking of the ethynyl endcaps over the temperature range 200-250 C. The low temperature crosslinking process was explained by thermolysis of the PEG molecules over this temperature range forming free radical species such as ?CH2CH2O or ?CH 2CH2 which initiate cure of the ethynyl groups resulting in a cross linked polyimide membrane. The PEG solvents also provide a radical source for the degradation polymerization of the solvents to a water and NMP insoluble polymer, which formed a miscible blend with the crosslinked membrane. Glass transition temperature (differential scanning calorimetry) data and thermo gravimetric analysis data provide evidence for the miscible blend.

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Reference：
Benzofuran – Wikipedia,
Benzofuran | C8H2928O – PubChem

Application of 18959-30-3, Because a catalyst decreases the height of the energy barrier, its presence increases the reaction rates of both the forward and the reverse reactions by the same amount.18959-30-3, Name is 4,5-Difluorophthalic Anhydride, molecular formula is C8H2F2O3. In a article，once mentioned of 18959-30-3

High stability of low-kappa value in a broad temperature region is a critical property for low dielectric constant polymer materials especially when they are served in some harsh conditions. However, most polymer dielectrics always exhibit a significant variation in dielectric property at around Tg or sub-Tg due to the local segment or chains motion, thus, low-kappa polymer dielectrics are limited to a relatively narrow working temperature region. Herein, we described a series of novel crosslinked polyimide (PI) thermosets by blending a reactive Cardo-containing diluent into the PI oligomer, the dielectric constants of which were greatly reduced from 3.4 to 2.5 and were surprisingly stable over a temperature region of -150-250 C. Meanwhile, the cured blended thermosets exhibited a 32?139 C increase in Tg compared to the pristine PI. Detailed analyses have illustrated that the significantly reduced kappa value, highly stable dielectric property and superior stability of these blended samples are originated from the synergistic effects of the large free-volume of Cardo-containing diluent, looser molecule packing resulted from the TR reaction and the highly crosslinked network. This desirable combination of facile processability, attractive dielectric behavior and excellent thermal stability makes them potential utilization in aerospace, microelectronic industries and other harsh environment applications.

A reaction mechanism is the microscopic path by which reactants are transformed into products. Each step is an elementary reaction. In my other articles, you can also check out more blogs about 18959-30-3

Reference：
Benzofuran – Wikipedia,
Benzofuran | C8H2950O – PubChem

Synthetic Route of 18959-30-3, A catalyst don’t appear in the overall stoichiometry of the reaction it catalyzes, but it must appear in at least one of the elementary reactions in the mechanism for the catalyzed reaction. 18959-30-3, Name is 4,5-Difluorophthalic Anhydride, molecular formula is C8H2F2O3. In a Patent，once mentioned of 18959-30-3

Disclosed is a highly reliable material for flexible printed wiring boards which enables fine wiring. Specifically disclosed are a compound represented by the general formula (I) below, and a resin composition containing such a compound as a reactive monomer. (I) (In the formula, one of X and Y represents =O and the other represents =NAr2R2; and R1, R2, Ar1 and Ar2 are as defined in the description.)

Balanced chemical reaction does not necessarily reveal either the individual elementary reactions by which a reaction occurs or its rate law.Synthetic Route of 18959-30-3. In my other articles, you can also check out more blogs about 18959-30-3

Reference：
Benzofuran – Wikipedia,
Benzofuran | C8H2915O – PubChem