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Showing 1 to 20 of 73 for “"Polyimides"”.
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Novel high performance thermosetting polyimides
… reproducibly exhibit fully imidized soluble polyimides with <Mw>/<Mn> values of ~2.0 determined by gel permeation chromatography (Universal Calibration). Successful molecular weight control was achieved using the reactive endgroups with imide oligomers synthesized with <Mp> values of 2,000 to …
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Synthesis and Characterization of Aryl Phosphine Oxide Containing Thermoplastic Polyimides and Thermosetting Polyimides with Controlled Reactivity
Phosphorus containing monomers, bis(3-aminophenyl)methyl phosphine oxide (m-DAMPO) and bis(3-aminophenyl)phenyl phosphine oxide (m-DAPPO), were synthesized and incorporated into a thermoplastic poly(arylene ether imide) based upon 2,2'-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride and …
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Partially-Fluorinated Polyimides using Aliphatic Diamines
Two series of polyimides were created in order to address several of the existing problems with gas permeation membranes used today. These issues include the lack of flexibility and inverse ratio that exists between selectivity and permeation. The approach taken in order to solving the flexibility …
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Analysis of hairy-rod polyimides for photoalignment
The evaluation of novel polyimides for nematic liquid crystal alignment by UV irradiation was the aim of this thesis. Homeotropic liquid crystal (LC) alignment was observed for the majority of the in-house synthesised hairy-rod polyimides (PIs). Oblique unpolarised UV irradiation of branched PIs …
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The synthesis and characterization of semicrystalline polyimides
Polyimides derived from 2,2-bis[4-(4-aminophenoxy)phenyl]-hexafluoropropane (BDAF) and pyromellitic dianhydride (PMDA) displayed a glass transition temperature (Tg) at 306°C and a melting point (Tm) near 470°C as measured by differential scanning calorimetry (DSC) with a heating rate of 10°C/min. …
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Electrical properties of polyimides modified with metal salts
Polyimides, due to their high thermal stability, excellent chemical stability, useful mechanical properties, and extremely high electrical resistivity, are utilized in aerospace, electronic, and specialty consumer markets. However, in some applications, lower electrical resistivity is preferable. …
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Surface characterization and adhesion of plasma-modified polyimides
… and argon plasmas appear to react with the polyimides via a fragmentation/oxidation mechanism, forming a loosely attached layer composed of low molecular weight polymer chains. The effect of ammonia plasma is postulated to be imide ring-opening resulting in the formation of amide functional …
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Isocyanate-derived organic aerogels: polyurethanes, polyureas, polyamides and polyimides
… acids (polyamides); and, (d) acid anhydrides (polyimides). All processes are invariably single-step, one-pot and take place at room temperature or slightly elevated temperatures. The resulting materials are robust, they have very wide range of densities and their nanomorphologies vary from …
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Synthesis and characterization of soluble, high temperature aromatic polyimides
High molecular weight, soluble polyimides were synthesized by a non-traditional synthetic route utilizing solution imidization techniques and diester-diacid derivatives of various commercially available dianhydrides. "One pot" syntheses were conducted using a solvent system of N-methylpyrrolidinone …
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X-ray scattering and molecular modeling of novel semicrystalline polyimides
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1994.
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Advancing Vat Photopolymerization of Photosensitive Polyimides: Process-Structure-Property Relationships
… performance, and are highly flammable. Aromatic polyimides have found broad adoption in aerospace, automotive, and electronics applications due to their exceptional thermal stability, mechanical strength, and chemical resistance. Their excellent dielectric properties are particularly advantageous …
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The study of capillary electrophoresis: polyimides, nylon and non-aqueous analysis
… appear in the electropherogram. But different polyimides give different patterns on the electropherogram and the same monomer in different polyimides gives a similar pattern. This pattern of electropherogram can be considered as a "fingerprint" of the polyimide, just as a chromatogram obtained …
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Structure-Property Relationships and Adhesion in Polyimides of Varying Aliphatic Content
Aromatic polyimides have found widespread applicability which can be partially attributed to their thermal stability, chemical resistance, and high glass transition temperature. However, deficiencies in their processability, solubility, transparency, and relatively high dielectric constants do not …
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The application of siloxane modified polyimides as high performance textile coatings
… as a function of chemical composition. The polyimides were then utilized to coat prototype fibers which were subsequently evaluated regarding thermal stability, thermal behavior, and hydrophobicity. The polymer series included poly(imide siloxane)s which were prepared in two steps, the first …
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Block Copolymer-derived Porous Polyimides and Carbon for High-Performance Energy Storage
Block copolymer-derived nanoporous materials are featured with microstructures defined by the microphase separation of constituent blocks, enabling various applications in energy storage. Dictated by the molecular weights and volume fractions of constituent blocks, the microphase separation forms …
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Crystallization, Morphology, Thermal Stability and Adhesive Properties of Novel High Performance Semicrystalline Polyimides
… to develop high temperature and high performance polyimides that also display (a) thermal stability; (b) crystallinity in the initial material and ability to crystallize from the melt; (c) fast crystallization kinetics and (d) melt processability. This unique combination of properties is presently …
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Synthesis and Characterization of Sulfonated Polyimides as Proton Exchange Membranes for Fuel Cells
Series of homo- and copolyimides containing controlled degrees of sulfonic acid ion conducting pendant groups have been synthesized from both phthalic (five-) and naphthalic (six-membered) dianhydrides and appropriate wholly aromatic diamines and heterocyclic analogues. The goal is to identify …
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Synthesis and Characterization of Wholly Aromatic Semicrystalline Polyimides Based Upon Bis(4-Aminophenoxy) Benzenes
Semicrystalline thermoplastic polyimides based upon bis(4-aminophenoxy)benzene and related "triphenyl ether" diamines were synthesized via the classical two step amic acid route. More specifically, polyimides were derived from para linked 1,4-bis(4-aminophenoxy)benzene, or TPEQ (triphenyl ether …
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Adhesion study of thermoplastic polyimides with Ti-6Al-4V alloy and PEEK-graphite composites
… The adhesive bond performance of these polyimides was investigated as a function of molecular weight, siloxane incorporation, residual solvent, test temperature, and polyimide structure via single lap shear samples prepared from treated Ti-6AI-4V alloy adherends and compression molded …
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Tailoring Reactivity, Architecture and Properties of High Performance Polyimides: From Additive Manufacturing to Graft Copolymers
… additive manufacturing of both high performance polyimides and polyetherimides using vat photopolymerization (VP). The use of small molecule precursors over previously investigated polymeric precursors displayed much lower solution viscosities yielding reduction of organic solvent loading, …
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