ISSN:0022-233X    

DOI:10.1080/10601326908051936

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The work directed toward the syntheses of thermally stable organic polymers which has been carried out in this laboratory over the past few years is reviewed. The syntheses of polyaromatic five-membered hetero-cycles obtained from the 1,3 dipolar addition reactions of disyndones and dinitrilimines, obtained from both hydrazide chloride and tetrazole precursors, show that the tetrazole monomer produces the highest-molecular-weight polypyrazole. All the polypyrazoles have good thermal stability. The 1,4 cyclo-addition reactions of bis-tstracyclones with diacetylenes afford high-molecular-weight phenylated polyphenylenes which are colorless, amorphous, and soluble in common organic solvents and have excellent thermal stability. Dipyrones are not as suitable double dienes as the bis-tetracyclones, since high-molecular-weight polyphenylenes are not obtained. The syntheses of high-molecular-weight linear poly-quinoxalines by the reaction of some bis-glyoxals with aromatic bis-o-diamines lead to thermally stable materials. By the condensation of suitable tetraketones connected by aromatic rings with the appropriate aromatic tetraamines, ladder polyquinoxalines with extremely good thermal stability can be obtained.

ISSN:0022-233X    

DOI:10.1080/10601326908051937

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The condensation of the aliphatic spirotetraamine 2,2-bis(aminomethyl)-1,3-diaminopropane (I) or 1,4-bis(aminomethyl)-1,4-diaminocyclohexane (II) with pyromellitic dianhydride (III) or 1,4,5,8-naphthalenetetracar-boxylic dianhydride (IV) was studied. It was found that in polyphos-phoric acid at temperatures greater than 200°C and after long reaction times, either tetraamine produced the desired spiropolymer with the dianhydride (IV), but only tars could be isolated when the dianhydride (III) was used. Although these condensations proceed through a polyimide precursor which then cyclizes by elimination of water, condensations of (II) with (IV) only yielded the fully cyclized material and all attempts to isolate the imide precursor failed. Strong evidence for total cyclization was obtained by comparing the infrared and ultraviolet spectra of the polymer and of model compounds that were representative of the fully cyclized and imide forms. Condensations of (I) and (IV) yielded polymers that were only 50% cyclized. The polymer based on spirotetraamine (I) started to lose weight at 300°C in both air and vacuum, while the polymer based on amine (II) showed no weight loss until 500 C in vacuum and 400°C in air.

ISSN:0022-233X    

DOI:10.1080/10601326908051938

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

This investigation was undertaken to determine the properties of a series of polymers based upon various aromatic diamines and several isomeric diketones. Consequently, six isomeric polymers were synthesized by the acid-catalyzed polycondensation of p- and m-dibenzoylbenzene with o-, p-, and m-phenylenediamine. Two fluorine-containing, isomeric polymers were also synthesized by condensing m-dibenzoylbenzene with tetrafluoro-m-phenylenediamine and tetrafluoro-p-phenylenediamine. Comparative thermal stabilities of the products both in air and under a nitrogen atmosphere were investigated by thermogravimetric analysis. Several of the polymers exhibited a high degree of thermal stability and all of the polymers exhibited essentially the same resistance to initial thermal decomposition in the oxidative as well as the nonoxidative atmosphere. A correlation of molecular structure and geometry with thermal stability and solubility is discussed and a mechanism for initial thermal decomposition of some of the polymers is proposed.

ISSN:0022-233X    

DOI:10.1080/10601326908051939

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The preparation of derivatives of 4-nitro- and 4-amino-1,2-benzene-disulfonic acid and 3,3′,4,4′-biphenyltetrasulfonic acid are described. Evidence is also presented for the facile elimination of sulfonyl groups from these compounds, particularly in reactions directed toward the formation of acid chlorides.

ISSN:0022-233X    

DOI:10.1080/10601326908051940

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Basic questions concerning heterocyclic polymers are reviewed. Initial investigations on the heterocyclic polymer BBB prepared from napthalene-1,4,5,8 tetracarboxylic acid and 3,3′-diaminobenzidine are described. These include infrared absorption studies of the structure of the polymer, fractionation of the polymer by exclusion chromatography on a porous substrate, and light scattering and dilute solution viscometry on fractions of the polymer dissolved in a strong acid. These data are interpreted to conclude that: (1) in dilute solutions BBB behaves as a “flexible coil” macromolecule, with perhaps relatively free rotation about the single bond connecting the long, inflexible, nearly planar repeat units; (2) a sufficient amount of interchain complex formation occurs in the solid state to give the linear, noncrystalline polymer some of the physical properties of a highly cross-linked network polymer.

ISSN:0022-233X    

DOI:10.1080/10601326908051941

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

A comparative thermogravimetrie study of eight polyimidazopyrrolone films of varying composition revealed that the thermal stability of the polymers increased with increasing theoretical percentages of carbonyl groups within the polymer repeat unit. The films degraded more rapidly in air than in vacuo, but the order of stability was the same in the two environments. Dynamic heating of the film in vacuo developed three distinct temperature regions in which maximum rates of weight loss occurred at characteristic temperatures, and each temperature region was associated with the evolution of a particular gaseous species.

ISSN:0022-233X    

DOI:10.1080/10601326908051942

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The decomposition in vacuum of a cured polyimide resin (Skybond 700) was studied in detail using simultaneous mass spectral and differential thermal analysis. These data were complemented with kinetic studies of the polymer and selected model imides. The mechanisms involved in the decomposition of Skybond 700 at moderate temperatures were determined using the combined results. It was discovered that the major endotherm seen in the thermogram was due to three simultaneous reactions: 1) Rupture of the benzophenone carbonyl bond to yield CO, 2) rupture of the imide bond to yield CO, and 3) rupture of the imide bond to yield CO2. Reaction 3 is in conflict with previous studies where CO2 was reported to arise from impurities in the polymer. The imide linkage as a source of C02 was substantiated by studying the degradation of model imide compounds. The decomposition rate of each of the models, in the vapor phase, was found to be first order, as was the rate of formation of CO2. It was then postulated that CO3is formed in the decomposition of the imide linkage by an intromolecular rearrangement through an ionic isomeric intermediate. Reaction rates were determined for the models, and the activation energies for each of the competing decomposition reactions for N-phenylphthalimide, the model most closely related to the polymer imide linkage, were calculated.

ISSN:0022-233X    

DOI:10.1080/10601326908051943

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The thermomechanical behavior (less than 1 Hz) of a newly available, high temperature, aromatic polysulfone has been investigated by the technique of lorsional braid analysis (TBA). Speculations concerning the synthesis and structure are discussed in terms of NMR and infrared spectroscopy, elemental analysis, and a review of the general literature on polysulfones. In addition to the glass transition at 287°C, a secondary relaxation was detected in the glassy state at −100°C by a mechanical loss maximum and change in modulus. The stability of the polysulfone at elevated temperatures in air and nitrogen as monitored by TBA, DTA, and TGA is reported. The influence of heat to 500°C, high doses of ionizing radiation, and water on the transitions of the polymer is discussed.

ISSN:0022-233X    

DOI:10.1080/10601326908051944

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Segal:Three years ago when the Polymer Group of the Southern California Section, ACS, held its last symposium on high-temperature polymers (seeHigh-Temperature Polymers, Marcel Dekker, New York, 1967) a similarly constituted, and equally illustrious, panel was asked: “Where do we go next in regard to the synthesis, characterization, and processing of thermally stable polymers?”

ISSN:0022-233X    

DOI:10.1080/10601326908051945

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor