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An analysis of the conformation of a stiff-chain polyimide in solution is given. It is shown that these polyimides exhibit the rather low persistence length of 13 nm despite the fact that the repeating unit consists of stiff and fully linear building blocks. A comparison with recent experimental and theoretical findings on similar systems corroborates the present analysis and suggests the bending...
Four polyimides and one polypyrrolone derived from 2,2 -bis(p-trimellitoxyphenyl) propane dianhydride were synthesized and the transport properties of H 2 , O 2 and N 2 in these polymers were measured at 30°C and 1 atm (1.01 10 5 Pa). Values of permeability and permselectivity were significantly affected by diffusivity and diffusivity selectivity, respectively...
A molecular simulation technique, combined with X-ray diffraction measurements, was applied to the determination of the crystal structure of poly(4,4 -diphenylene pyromellitimide), a high-modulus aromatic polyimide. Simulation of the crystal structure was carried out with the programs POLYGRAPH and CERIUS (Molecular Simulations Inc.) using the Dreiding force field approach. Initial models optimized...
A quaternary copolymer, containing 1,2,4,5-benzene tetracarboxylic dianhydride (PMDA), 4-aminophenyl ether (ODA), aminopropyldimethyl terminated polydimethylsiloxane (PSX) and 2,5-diaminobenzene sulfonic acid (DABSA), has been successfully synthesized to become an ionic conductor for electrochemical applications. It combines the functions of immobilized anionic groups (SO -3 ) incorporated...
A new route has been developed for the synthesis of thermally stable polymer foams with high glass transition temperatures. Compositionally asymmetric microphase-separated block copolymers were prepared where the minor component, poly(α-methylstyrene), is thermally labile and the major component, polyimide, is thermally stable. The minor component can unzip, to its monomer upon heating, and the...
The objective of this work is to study the surface property changes of carbon fibres resulting from the electrodeposition of polyamic acid. Unsized but surface oxidized carbon fibres were successfully coated with polyamic acid by non-aqueous electrodeposition. The surface property changes due to the electrodeposition were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy...
This present investigation deals with the miscibility, phase behaviour and semicrystalline morphology of new thermoplastic polyimide (N-TPI)/poly(ether imide) (PEI) blends with different compositions. Melt-quenched amorphous blends were used as the raw materials. The phase behaviour of the blends has been studied by means of differential scanning calorimetry (d.s.c.). It has been found that the...
Polyimide (PI) surfaces were modified to improve the adhesion strength of epoxy resin/PI joints by immersing in amine solutions. Adhesion strength of epoxy resin/amine-treated PI joints were measured depending on structure, molecular weight, concentration, treatment time and drying temperatures of amines. There was an optimum drying temperature for maximum adhesion strength after amine-treatment...
Gas transport of carbon dioxide, oxygen, nitrogen and methane gases in a series of poly(phenylene thioether imide)s based on 2,2-bis(3,4-decarboxyphenyl) hexafluoropropane dianhydride and diamine-terminated oligo(phenylene thioether)s has been investigated. The effects of the oligo(phenylene thioether) length on the gas permeabilities and diffusivities were determined and correlated with chain packing...
Different molecular weight samples of a polyimide, 6FDA-PFMB, were synthesized from 2,2 -bis (3,4-dicarboxyphenyl) hexafluoropropane (6FDA) and 2,2 -bis(trifluoromethyl)-4,4 -diaminobiphenyl (PFMB) in refluxing m-cresol at high temperatures through a one-step polymerization route. Films of 6FDA-PFMB ranging from 1 to 100 μm thickness were prepared via solution-casting and investigated using optical...
Para-para linked aromatic poly(amic ester) precursors of rodlike polyimide (PI) BPDA-PDA and polyetherimide (PEI) HQDPA-ODA were synthesized. The para-para linked poly(amic ester)s were employed in this work to obtain, in theory, full-imidized polyimides. The two precursors were mixed by dissolving them in N, N -dimethyl acetamide and subsequently coagulating in methanol. After thermal imidization,...
Polymers were synthesized with 1,3-bis[4-(4-aminophenoxy)-α,α-dimethylbenzyl]benzene by polycondensation of pyromellitic dianhydride (PMDA), phthaloyl chlorides and trimellic anhydride chloride (TAC). Their possible use as aromatic thermotropic liquid crystalline polymers was investigated. The polyamide from terephthaloyl chloride (TPC), and the copolyamideimide from PMDA and TPC, showed thermotropic...
The adhesion behaviour or lack thereof, of polyimides is well known. The inherent brittleness of epoxy resins has also led to a search for additives to improve the physical properties of epoxy. In order to improve both of these properties, we utilized a unique strategy to cure a diepoxy (diglycidyl ether of bisphenol A) with a polyamic acid derived from oxydianiline and pyromellitic dianhydride. The...
Effects of the drying condition on thermo-mechanical properties and morphology of PI(BPDA/PDA) were investigated. Polyamic acid and polyamic acid esters were used as precursors of the polyimide. Thermal expansion coefficients (TECs) of the polyimide films are strongly affected by precursor structures. The esters give larger TECs than the polyamide acid does. TEC of polyimide film from polyamide...
The poly(amic ethyl esters) (PAEs) of pyromellitic dianhydride/4,4 -oxydianiline (PMDA/ODA) were prepared in three isomeric forms, with meta-linkages, para-linkages and randomly alternating meta- and para-linkages (referred to as mixed PAEs). In addition to the normal PAEs (which contained only hydrogen and which were cast as base layers for diffusion studies), each of these isomeric PAE was synthesized...
Soluble poly(p-phenylene biphenyltetracarboxamine acid) (BPDA-PDA PAA) precursor, which was synthesized from biphenyltetracarboxylic dianhydride and p-phenylene diamine in N-methyl-2-pyrrolidone (NMP), was spin-cast on silicon substrates, followed by softbake at various conditions over 80-185°C. Softbaked films were converted in nitrogen atmosphere to be the polyimide films of ca. 10 μm thickness...
We have synthesized a difunctional model compound PAS-HFDE-PAS, obtained by condensation between a dianhydride (6-HFDA), hexafluoroisopropylidene-2,2′-bis (phthalic acid anhydride) and two mole equivalents of para-aminostyrene (PAS) amines. It was then characterized using spectroscopic and thermal methods, including a kinetic study of monomer reactivity in the temperature range of 100–300°C. The results...
Monolayers of alkyl side chain substituted preformed polyimides (BACBP/BPDA) exhibit behaviour different from that of other hairy-rod polymers which were studied previously. This behaviour is thought to arise from the extreme rigidity of the backbone as well as the particular way in which the alkyl side chains extend from the biphenyl unit. These soluble polyimides can form metastable monolayers...
Most aromatic poly(amic acid)s, which are precursor polymers of polyimides, are thermally converted to the corresponding polyimides via imide-ring closure formation over their glass transition temperature (T g ) ranges or below. In addition, it is very difficult to remove completely solvents used in the synthesis from their cast samples, due to the formation of complexes between the solvent...
The synthesis of a series of N-(hydroxyphenyl) succinimides is described along with their reaction with HMTA. The succinimides serve as a model for the more complicated polyimide/HMTA systems. Both benzoxazine and benzylamine type intermediates have been identified as the initial major intermediates formed depending on the substitution pattern of the phenolic ring. The rate of reaction of HMTA...
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