Journal ArticleDOI
Morphology of a phase-separated and a molecular composite PBT/ABPBI polymer blend
Stephen Krause,Tim B. Haddock,G. E. Price,P. Galen Lenhert,Joseph F. O'brien,Thaddeus E. Helminiak,W. Wade Adams +6 more
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TLDR
The structure and morphology of homopolymers and blends of rigid-rod poly(p-phenylene benzobisthiazole) (PBT) and semiflexible coil poly[2,5(6)benzimidazole] (ABPBI) were examined by wide-angle x-ray diffraction and scanning and transmission electron microscopy as discussed by the authors.Abstract:
The structure and morphology of homopolymers and blends of rigid-rod poly(p-phenylene benzobisthiazole) (PBT) and semiflexible coil poly[2,5(6)benzimidazole] (ABPBI) were examined by wide-angle x-ray diffraction and scanning and transmission electron microscopy. When samples were processed from a solution where the total polymer concentration of 30% PBT/70% ABPBI blend was greater than a critical concentration, large-scale phase separation occurred and 0.1–4 μm ellipsoidal particles were present in a ductile matrix. The ellipsoids were chiefly composed of aggregates of well-oriented 10-nm PBT crystallites, while the matrix material was chiefly ABPBI. When the concentration was less than a critical concentration, the solution was optically homogeneous. In processing of fiber and film samples from the homogeneous solution, large-scale phase separation was inhibited by rapid coagulation in a water bath. After heat treatment, these samples were found to contain crystallites of both PBT and ABPBI with lateral dimensions of ordered regions no larger than 3 nm. The PBT homopolymer was dispersed in the matrix at the molecular level in ordered regions at a scale no larger than 3 nm, resulting in a rigid-rod molecular composite. In the rigid-rod molecular composite fiber both the molecular-level dispersion and high orientation contributed to higher values of strength and modulus compared to the properties of a phase-separated fiber. The strength and modulus of highly oriented fiber were only 25% higher than those of planar isotropically oriented film, suggesting that the level of dispersion of rod molecules is more important than orientation of the reinforcing phase in rigid-rod molecular composites.read more
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Photophysics, photochemistry, and optical properties of polyimides
M. Hasegawa,Kazuyuki Horie +1 more
TL;DR: In this article, a review of charge transfer interactions in wholly aromatic polyimides (PI) is presented, and the influence of CT interactions on PI properties, including photophysics, photochemistry, optical properties, and other properties is discussed.
Journal ArticleDOI
Polymer Electrolyte Fuel Cells Based on Phosphoric Acid-Impregnated Poly(2,5-benzimidazole) Membranes
TL;DR: In this paper, the authors reported the characterization of poly 2,5-benzimidazole (ABPBI) as thin as 20 mm for polymer electrolyte membrane fuel cells with high thermal stability and good proton conductivity at temperatures up to 200°C.
Journal ArticleDOI
Proton-conducting membranes based on poly(2,5-benzimidazole) (ABPBI) and phosphoric acid prepared by direct acid casting
TL;DR: In this article, the authors reported the preparation of poly(2,5-benzimidazole)/phosphoric acid/methanesulfonic acid (MSA) solution.
Journal ArticleDOI
Improvement of thermoplasticity for s-BPDA/PDA by copolymerization and blend with novel asymmetric BPDA-based polyimides
TL;DR: In this article, a-BPDA-derived polyimides were used as matrix polymers for semirigid polyimide homo-polymers for the present purpose.
Journal ArticleDOI
Spontaneous Molecular Orientation of Polyimides Induced by Thermal Imidization. 3. Component Chain Orientation in Binary Polyimide Blends
TL;DR: The degrees of uniaxial and in-plane molecular orientation for homopolyimides (PI) and PI/PI binary blends were estimated from the absorption dichroism of perylenetetetracarboxydiimide (PEDI) bound as discussed by the authors.
References
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TL;DR: Reciprocity of specimen lifetime and current density at the specimen demonstrates the absence of any dose-rate effect, such as specimen heating, as a cause of specimen damage within the range 10−3 to 10−5 amperes/cm2 current densityat the specimen.
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TL;DR: A condensed description of the fundamental processes involved in radiation damage and the effects of radiation on the physical and chemical properties of organic materials, particularly polymers, is given in this paper, where it is shown that the radiation doses received by specimens in the electron microscope are extremely high, very much greater than those used in radiation chemistry experiments.
Review Radiation damage and electron microscopy of organic polymers
D. T. Grubb,H. H. Wills +1 more
TL;DR: In this article, a condensed description of the fundamental processes involved in radiation damage and the effects of radiation on the physical and chemical properties of organic materials, particularly polymers, is given.
Journal ArticleDOI
A new method for optimal-resolution electron microscopy of radiation-sensitive specimens
TL;DR: In this article, a new technique as well as a practical device, Minimum Dose System (MDS), have been developed for taking a high resolution image of radiation-sensitive specimens, on the basis of the principle of minimum beam method.
Journal ArticleDOI
Electron energy loss studies of polymers during radiation damage
TL;DR: In this article, the energy loss spectra of fast electrons passing through an extremely small sample were studied using the energy-analysing electron microscope. And the spectrum from each polymer was quite similar to that of amorphous carbon, and the energy losses of the main peak always increased with irradiation.