PBIs

Jesson B J, Foley M and Madden P A 1997 Thermal properties of the self-interstitlal In aluminum an ab initio molecular-dynamics study Pbys. Rev. B 55 4941-6... 

AokI M I and Tsumuraya K 1997 Ab initio molecular-dynamics study of pressure-induced glass-to-crystal transitions In the sodium system Pbys. Rev. B 56 2962-8... 

Watson S C and Carter E A 2000 Linear-scaling parallel algorithms for the first principles treatment of metals Comp. Pbys. Common. 128 67-92... 

Hedin L 1965 New method for calculating the one-particle Green s function with application to the electron-gas problem Pbys. Rev. 139 A796... 

Causa M, DovesI R and RoettI C 1991 Pseudopotentlal Flartree-Fock study of seventeen lll-V and IV-IV semiconductors Pbys. Rev. B 43 11 937-43... 

Chartler A, D Arco P, DovesI R and Saunders V R 1999 Ab initio Flartree-Fock Investigation of the structural, electronic, and magnetic properties of MOjO Pbys. Rev. B 60 14 042-8, and references therein... 

Polybenzimidazole (PBI) Fibers. Poly(2,2 -(y -phenylene)-5,5 -bisbenzimidazole) [25734-65-0] is a textile fiber marketed by Hoechst-Celanese (11) which does not form Hquid crystalline solutions due to its bent meta backbone monomeric component. PBI has exceUent resistance to high temperature and chemicals. 

PBI is being marketed as a replacement for asbestos and as a high temperature filtration fabric with exceUent textile apparel properties. The synthesis of whoUy aromatic polybenzimidazoles with improved thermal stabUities was reported in 1961 (12). The Non-MetaUic Materials and Manufacturing Technology Division of the U.S. Air Force Materials Laboratory, Wright-Patterson Air Force Base, awarded a contract to the Narmco Research and Development Division of the Whittaker Corp. for development of these materials into high temperature adhesives and laminates. 

Development efforts at Celanese Research Co. estabHshed soHd-state polymerization as the most practical process for engineering scale-up. Homogeneous solution polymerization of PBI in polyphosphoric acid was eliminated because of the need to work with low soHd compositions (in the range of 3—5%) during the precipitation, neutralization, and washing steps required for isolation of the product. 

Body fluids are analyzed for T and T by a variety of radioimmunoassay procedures (31) (see Immunoassays). The important clinical parameter for estimating thyroid function, the protein-bound iodine (PBI), is measured as described in treatises of clinical chemistry. High performance Hquid chromatographic (hplc) methods have replaced dc (32,33). 

PolybenZimidaZoles. The polyben2imida2oles (PBIs) are generally produced by the high temperature, melt polycondensation reaction of aromatic bis-ortho-diamines and aromatic dicarboxylates (acids, esters, or amides) in a reaction such as that shown in equation 11 to form ben2imida2ole [51-17-2] as the repeating unit. 

A large number of PBIs have been investigated since their first synthesis in 1961 (35) the particular polymer used in many commercial and developmental appHcations is poly(2,2 -y -phenylene)-5,5 -diben2imida2ole). 

The distinction between thermoplastic and thermoset is particularly cloudy in the case of PBIs because they are formed and processed as thermoplastics but after processing exhibit properties that are more closely related to thermosetting materials. Hence they, too, are usually considered pseudothermoplastics. 

Studies of die structures of cuprate species were initiated to elucidate die niedi-anisnis by wbidi tliey interact witli substrates and to understand dieit special reactivities. tn die early days tliese investigaiions were restricted to solution studies by spectroscopic tediniques. It was not until 1982 dial tlie dtst example of a cuprate species - [iCu Pbi-jiLiiTHFj))] - was stiuctutally diatacterlzed by X-tay crystal stiucture deterniination [ 100] ivide infra). It sbotild be noted tliat most of diese studies, reviewed previously [29, 45, 101], were limited to "simple" alkyl and aryl derivatives. 

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