The Melting Point—Composition Diagram of the Zirconium—Oxygen System1

1951 ◽  
Vol 73 (5) ◽  
pp. 2032-2035 ◽  
Author(s):  
Daniel Cubicciotti



1957 ◽  
Vol 30 (1) ◽  
pp. 283-295 ◽  
Author(s):  
D. H. Coffey ◽  
T. J. Meyrick

Abstract By using diisocyanates to link together two different polyesters having terminal hydroxyl or carboxyl groups, copolymers have been obtained in which the two repeating units occur in blocks and not in the random arrangement obtained by normal methods of preparing copolymers. Melting points have been measured by a penetrometer method and the effects of copolymer composition on melting point determined. In a series of crystalline copolymers made by linking various amounts of polyethylene sebacate and polyethylene adipate with hexamethylene diisocyanate, a step-shaped melting point-composition curve is obtained. Copolymers containing up to about 40 per cent of polyethylene adipate have the same melting point as that of polyethylene sebacate. Further increase in the polyethylene adipate content results in a rapid drop in melting point until the melting point of polyethylene adipate is reached. Thereafter increasing amounts of polyethylene adipate do not alter the melting point. Random copolymers of ethylene adipate and ethylene sebacate give a V-shaped melting point-composition curve. The step-shaped curve of block copolymers is almost identical with the melting point-composition curve of melt blends of the two polymers. Stress-strain characteristics and impact strengths of the block copolymers have been measured. In the polyethylene adipate/polyethylene sebacate/ hexamethylene diisocyanate series no great differences are found between random and block copolymers. If, however, the crystalline polyethylene adipate is replaced by the noncrystalline polypropylene adipate, then block copolymers containing 15–30 per cent of polypropylene adipate have outstanding impact strength. Similar high impact strength is obtained by using a compatible rubbery polymer as an external plasticizer with hexamethylene diisocyanate modified polyethylene sebacate. This method of block copolymerization has an advantage over random copolymerization in that a crystalline copolymer can be modified without reduction of its melting point, and by suitable selection of a second component it affords a means of “building in” a plasticizer.



1956 ◽  
Vol 60 (6) ◽  
pp. 826-826 ◽  
Author(s):  
James B. McCormack ◽  
John H. Walkup ◽  
R. I. Rush


1953 ◽  
Vol 31 (6) ◽  
pp. 536-542 ◽  
Author(s):  
A. G. Brook ◽  
R. Donovan ◽  
George F Wright

The α- and β-2-methoxycyclopentylmercuric chlorides, bromides, and iodides have been prepared. The X-ray powder patterns, dipole moments, and thermal analyses among each series have been compared with the homologous methoxycyclohexyl derivatives. In both of the series the dipole moments of the β-diastereomers are greater than those of the corresponding α -isomers. In both series the α- and β-diastereomers seem to comprise isostructural series among the three halides. This isostructural relationship seems to be reflected in the melting point composition diagrams.



1966 ◽  
Vol 12 (10) ◽  
pp. 647-658 ◽  
Author(s):  
T C Chu ◽  
Edith Ju-Hwa Chu

Abstract The heptacarboxylic porphyrin (hepta) isolated from different types of porphyric urine samples contains different proportions of the isomers I and III. These were separated chromatographically. The hepta in congenital porphyria was found to contain 65% of Type I isomer and 35% of Type III; that in acute intermittent porphyria, 70-80% III and 20-30% I; and that in porphyria cutanea tarda, 80-90% III. Several other cases including 1 of coproporphyria, 1 of South African genetic porphyria, 1 of Bantu porphyria, 4 of hexachlorobenzene poisoning in Turkish individuals were also examined. From the X-ray diffraction pattern and long-column chromatography, the Hepta III prepared either from decarboxylation of Uroporphyrin III or by condensation of porphobilinogen revealed a more complex configuration than that isolated from porphyric materials. The natural hepta might be dominated by one of the four possible isomers of the III series. A melting-point composition curve of methyl esters of Hepta I and III was constructed, and its applicability was tested. The identity of the hepta isolated in porphyria cutanea tarda with "208" and "pseudouro" porphyrins is discussed, and the name "cutano-porphyrin" suggested.



1982 ◽  
Vol 59 (2) ◽  
pp. 157
Author(s):  
Bro. Leo P. Michiels ◽  
Raymond C. Barile ◽  
German F. de la Fuente




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