Design and characterization of polymers and polymer blends for high temperature structural applications

Reviewing the development of new polymeric materials for high temperature structural applications (T > 200°C) over the past several decades, reveals a paradox which, to date, has not been completely resolved. Polymers which exhibit very high temperature stability tend to be either intractable or brittle, whereas, easily processible polymers tend to fall short of property targets. Approaches to resolving this paradox include modification of the chain backbone chemistry and polymer blending (especially to form miscible systems). Recent research has shown that, in contrast to low temperature flexible polymers, many high temperature aromatic heterocyclic polymers form miscible systems which permit the design of the desired processibility and performance into the blend. An example of such a system is the blend of Poly(2,2′-(meta-phenylene-5,5′-bibenzimidazole) (PBI) with a series of polyamides, including commercially available polyether imide (PEI) and imide copolymers containing sulfone and fluorinated isopropylidene (6F) units. Other examples include all polyimide blends and blends of polyimides with polyethersulfone.     

Synthesis of methylene-bis(1-oxy-3,3-dialkyl-1-triazene 2-oxides) and their analogs

Synthetic procedures towards methylene-bis(1-oxy-3,3-dialkyl-1-triazene 2-oxides), the first representatives of a new class of promising exogenous nitric oxide (NO) donors, which can release NO in living organisms, were developed. Synthesis involves the reactions of salts of 1-hydroxy-3,3-dialkyl-1-triazene 2-oxides with either dibromomethane or 1-chloromethoxy-3,3-dialkyl-1-triazene 2-oxides.     

Coordination compounds of DyIII and NdIII with malonic and succinic acid bispicolylamidrazones

Russian Chemical Bulletin - Dysprosium(iii) and neodymium(iii) complexes with aliphatic dicarboxylic acid bispicolyl-amidrazones were synthesized and studied. X-ray diffraction data showed that the...     

Pressure induced resonance of the Raman linewidth of the A1 mode of Cu3V S4

Investigations of the Raman spectrum of Cu₃V S₄ under pressure up to 60 kbar show a pronounced enhancement of the linewidth of the A₁ mode around 20 kbar. This anomaly is interpreted in terms of a resonance between the A₁ mode and a double phonon structure arising from the combination of F₂ like zone center phonons.     

Multiple peak recordings in flow injection analysis

The quality and level of the information provided by conventional flow-injection systems can readily be enhanced by simple modifications. The different possibilities available for obtaining several peaks per injected sample are reviewed. Among the topics are simultaneous and sequential multidetection, multicomponent determinations (including speciation), reaction-rate methods, and automatic amplification of conventional analyte concentration ranges.     

Ward identities for non-commutative geometry

We interpret the cocycle condition in quantum field theory as a set of integrated Ward identities for non-commutative geometry.Dedicated to Res Jost and Arthur WightmanSupported in part by the National Science Foundation under Grants DMS/PHY 88-16214 and INT 87-22044     

An index theorem for super derivations

We show that the Chern character given by a super-KMS functional on a quantum algebra can be interpreted in terms of the index of a super derivation on a projection of the algebra.Dedicated to Roland DobrushinSupported in part by the National Science Foundation under Grant DMS/PHY 8816214