Polyhydrazides aromatic

Poly(terephthaloyl hydrazide) forms anisotropic solutions in concentrated solutions of some quarternary ammonium hydroxides such as tetramethyl ammonium hydroxide 33). These solutions contain typically about 10% each of the organic base and the polymer. Aromatic polyhydrazides such as poly(chloroterephthaloyl hydrazide) and various co-polyhydrazides also form anisotropic solutions in some of the solvents used for PPT, such as 100% sulphuric acid and fluorosulphonic acid 34). 

Polymer G is the aromatic polyhydrazide from terephthalic dihydrazide and terephthaloyl chloride -t-NHNHCO CONHNHCO CO. ... 

Cellulose Acetate Aromatic Polyamide Polybenzimidazole Polybenzimidzolone Aromatic Polyhydrazide Polyamidimide... 

Calculate the solubility parameters of (I) aromatic polyamide, (2) aromatic polyhydrazide, and (3) aromatic polyamidehydrazide. 

Aromatic polyhydrazides are well known from the work of Frazer, Wallenberger and Sweeny (1,2) as precursors to poly-1,3,4-oxadiazoles. Poly-amide-hydrazides have been described in detail by Black, Preston, and coworkers (3,4,5) and by Culbertson and Murphy (6). High tenacity, high modulus fibers have been made from poly(terephthalie hydrazide)(7) and from polyamide-hydrazides with ordered structures (5). 

There are only a few communications in the literature on the fabrication of fibers from LC polymers of a different chemical structure than aromatic polyamides and heterocyclic polyarylenes of the type of PBT or PBO, and they primarily concern aromatic polyhydrazides. These polymers can be considered polyamides prepared with hydrazine as the diamine. LC solutions of polyhydrazides based on terephthalic and oxalic acids have been prepared in both aqueous solutions of organic bases (secondary amines or quaternary ammonium bases) and in concentrated sulfuric acid [57]. In sulfuric acid, polyhydrazides are unstable and undergo hydrolytic decomposition, but the copolyhydrazide based on oxalic, chloro-, and terephthalic acids form relatively stable LC solutions in sulfuric acid... 

Phenoxaphosphine ring-containing poly (1,3,4-oxa-diazoles) were synthesized by cyclodehydration of poly-hydrazides obtained from (BCPO) and aliphatic and aromatic dihydrazines [152]. All these polymers are soluble in formic acid, w-cresol and concentrated H2SO4. The polyhydrazides yield transparent and flexible films when cast from DMSO solution under reduced pressure at 80-100°C. The polyhydrazides exhibit reduced viscosities of 0.24-0.40 dl/g in DMAC. Phenoxaphosphine ring-containing oxadiazole polymers showed little degradation below 400°C. 

Carbazole-containing PODs have been obtained (53) by cyclodehydration (in the presence of POCl3) of polyhydrazides prepared by polycondensation of IV-ethyl-3,6-carbaZoledicarbonyl chloride with dihydrazides of the corresponding dicarboxylic acids. Thermal decomposition of the polymers containing aliphatic units occurs at 365-380°C, compared to 400-405°C for polymers containing aromatic units. 

Fully aromatic, thermally (up to 250°C) and hydrolytically resistant films of PODs have been realized from polyhydrazides (56). Films of these polymers are useful as seawater desalination membranes. 

The synthesis of phenoxaphosphine-containing PODs by the cydodehydration of polyhydrazides obtained from 2,8-dichloroformyl-10-phenylphenoxaphosphine-10-oxide and aliphatic and aromatic dihydrazides has been described (60). All polymers are soluble in formic acid, -cresol, and cone H2S04, but insoluble or partially soluble in benzene, chloroform, and hexamethylphosphoric triamide. 

Polyamides and their analogue are also effective for the selective membranes and there have been developed many kinds of permselective membranes. In early 1960 s, du Pont started to investigate the membranes for demineralization of water by reverse osmosis. After screening polymers, aromatic polyamides and polyhydrazides were shown to have superior properties9-11. In the present review various polyamides and their analogue are in focus as barrier materials for membranes, and their permeative characteristics will be discussed from the view point of their chemical structures. 

Structure Level I. Structure Level I variations for aromatic polyamides are broad. The wide range of segmental structures possible with these polymers is what makes them so interesting for membrane science. The discussion of Structure Level I will be limited to some representative segmental units in polyamides, polyhydrazides and polyamide-hydrazides. Structures and abbreviations for some typical diamines that are condensed with mixtures of isophthaloyl chloride (l) and terephthaloyl chloride (T) to give the aromatic polyamides discussed in this paper are shown in Table III. 

Major contributions to the synthesis of aromatic polyamides were made by Morgan, Kwolek and coworkers ( 1.- ) G. N. Milford prepared the aromatic polyamide and J. W. Richter synthesized the polyhydrazides and polyamide-hydrazide discussed in this paper (.7). Other investigators have also contributed extensively to the synthesis and characterization of aromatic polyamides for example, Preston and coworkers at Monsanto (8-10). Important contributions to the polyamide synthesis literature have also been made by Australian, Canadian, European, Japanese and Russian scientists (11). 

The flux of 0.03 gfd for the homogeneous polyamide membrane was more than two orders of magnitude too low for commercial desalination. The flux was increased 175 fold with no decrease in salt rejection by casting the membrane with asynmetric morphology. Even higher fluxes, up to 3.5 times that observed for the asymmetric MPD-l/T (100-70/30) polyamide membrane, were obtained with asymmetric membranes cast from polyhydrazides and polyamide-hydrazides. Permeation properties for the three types of aromatic polyamides are shown in Table IX. The RO properties of this group of membranes illustrate the combined effects of Structure Levels I, II and III on membrane performance. 

Within the last two decades, a number of chemical structures have been proposed as metal deactivators for polyolefins. These include carboxylic acid amides of aromatic mono- and di-carboxylic acids and N-substituted derivatives such as N,N -diphenyloxamide, cyclic amides such as barbituric acid, hydrazones and bishydrazones of aromatic aldehydes such as benzaldehyde and salicylaldehyde or of o-hydroxy-arylketones, hydrazides of aliphatic and aromatic mono- and di-carboxylic acids as well as N-acylated derivatives thereof, bisacylated hydrazine derivatives, polyhydrazides, and phosphorus acid ester of a thiobisphenol. An index of trade names and suppliers of a few commercial metal deactivators is given in Appendix A4. 

Aromatic polyamides and polyhydrazides containing the oxalyl group... 

Ballistreri and co-workers [46] studied the thermal decomposition of some totally aromatic, totally aliphatic polyhydrazides or polyoxamides by direct Py-MS using both chemical ionisation and electron impact modes ... 

Recognition and Characterization of Licruid Crystalline Solutions, The same visual and physical characterization tests as used for aromatic polyamides (11) apply to recognition of liquid crystallinity in the polyhydrazide solutions. The solutions appear somewhat turbid, often exhibit an opalescent effect upon being stirred, depolarize plane-polarized light, are oriented by a strong magnetic field, and show a sharp decrease in bulk solution viscosity above the critical concentration point. 

Coloration in Polyhydrazide-Base Solutions. The wholly aromatic, para-linked polyhydrazides exhibit a deep yellow coloration in aqueous bases. This coloration is not shown in polymers wherein the aromatic rings are all meta-linked, or polyhydrazides derived from monomethylhydrazine (Table VIII). Intermediate color formation is shown by such polymers as alternating O-I-O-T and... 

Although not strictly the subject matter of this book, work is briefly reviewed next on the application of non mass spectrometric Py-GC methods in the determination of polymer structure. This information is inclnded in the hope, when necessary, that chemists will be able to adapt these methods by including a mass spectrometric detailed information on polymer structure acrylates [63, 105-107], rubbers [63, 108-110], PVC [63,111-115], aliphatic polyhydrazides [116], polyoxamides [116], polyamides [117], polyether imides [118], methacrylamide [119], aromatic aliphatic polyamides [117], polyurethanes [120], chitin graft poly(2-methyl 2-oxazolone) [121, 122], polyxylyl sulfide [123-126], epoxy resins [127], polyethylene oxalate [128], polytetrafluoroethylene [129], polyvinylidene chloride [129], polyepichlorohydrin, fluorinated ethylene-propylene copolymer [129], polyvinyl fluoride [129], polyvinylidene [129], fluoride [129], SBR copolymer [129] and styrene-isoprene copolymer [130]. 

Aromatic and aliphatic polyhydrazides and polyoxamides Chemical ionisation and electron impact MS - - Study of thermal decomposition process of polymers containing -CO-, -NR-NR-, linkages strongly influenced by structural features [41]... 

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