V.V. Korshak

Gas chromatographic study of thermal polycyclocondensation of heterochain polymers

Gas chromatography was used to examine kinetic relations of thermal solid phase ring formation of heterochain polymers. It was found possible to use this method for the study of single stage and two stage reactions of ring formation when producing heterocyclic compounds.

Effect of anomalous units on the heat resistance of pyrrones

Abstract The isothermal degradation of polyaminocarboxyamides, polybenzoylenebenzimidazoles based on the latter, and compounds modelling the elementary unit of these polymers has been investigated in an inert atmosphere. The volatile products of degradation have been analysed by gas-chromatography. The presence of anomalous incompletely cyclized units in the pyrrone macromolecule causes degradation of the polymer at lower temperatures.

The effect of the conditions of synthesis on the properties of polyamino amido acids

INTENSIVE studies are now being carried out abroad and in the Soviet Union of the synthesis of polymers prepared from aromatic tetra-amines and tetracarboxylic acid dianhydrides [1-14]. The most interesting results were obtained by two-stage synthesis using solvents, which made it possible to obtain soluble linear polymers (polyaminoamidoacids) capable of cyclodehydration at high temperatures [2-6]. Problems related to ring formation of polyaminoamidoacids were examined in many papers and thermal and thermal oxidative breakdown processes studied [1-14]; however, there is no systematic information in the literature concerning the effect of the conditions of synthesis on the molecular weight of the polymers studied. We therefore determined the effect of certain factors on the molecular weight of polyaminoamidoacids from the dynamic viscosity of the polymer solutions obtained. We studied 3,34,4-tetraaminodiphenylmethane (I) and pyromellitic dianhydride (II). The reaction system may be conventionally shown as: O O H2N NH2 ~

A study of thermal stability in a number of aromatic and nitrogen containing polycyclic compounds

Abstract A comparative study has been made by pyrolytic gas chromatography of the thermal stability of a number of aromatic and nitrogen containing polycyclic compounds modelling the units and individual fragments of the chain of heat resistant polymers. It is shown that introduction of various bridging groups between the benzene rings and reduction of the aromaticity of the cyclic systems bring about a decrease in thermal stability. It was found that the substances with greatest thermal stability are fully aromatic ring compounds and heterocyclic ring systems condensed with the benzene nucleus.

Comparative pyrolysis of imides and amido-acids in a confined space☆

Abstract A study has been made of the volatile products of pyrolysis over the temperature range of 200–650°, of a polyimide and a polyamido-acid based on benzidine and pyromellitic anhydride, and of compounds modelling the units of these polymers, namely N,N′-diphenylpyromellitimide and the dianilide of pyromellitic acid, as well as N-phenylnaphthalimide, the N,N′-diphenyldi-imide of 1,4,5,8-naphthalenetetracarboxylic acid, the dianilide of terephthalic acid and diphenyl terephthalate. A qualitative correspondence between the thermal decomposition of the polymers and of the compounds modelling their units is shown. It is shown that up to 400° the main reaction of amido-acids is cyclization. At about 500° imide rings become sources of carbon monoxide.

The link between the mechanical properties produced by thermal imidization of poly-(p,p′-diphenylenoxy)pyromellitic amic acid and the reaction conditions☆

The deformation-strength properties of films produced by a thermal imidization from poly-(p,p′-diphenylenoxy)pyromellitic amic acid (PDOPA) have been studied in a wide temperature range. The film properties were found to depend on the thermal polycyclization conditions; the intramolecular disintegration of the o-carboxyamide fragments above 200°C does not significantly affect the deformation-strength properties complex of the forming polymers when the reaction is carried out in the solid phase. The macromolecular type of initial reagents plays a decisive part at high imidization temperatures.

The heat-resistance of carding polybenzoxazoles (PBOA)☆

Abstract An investigation was carried out of the heat-resistances of aromatic polybenzoxazoles containing bulky polar groups, such as phthalide and N-phenylphthalimidine, in the main chain, and of a number of model compounds. The chemical composition of the polymers was found to affect the heat resistance.

New heat-resistant polymers from 4-carbophenoxynaphthalic anhydride and aromatic tetramines☆

Heat-resistant polymers have been prepared from 4-phenyl naphthalenetricarboxylic acid anhydride and aromatic tetramines by polycondensation in the melt. Some relationships of the reaction have been studied and the optimal conditions of preparation have been found. These polymers are soluble and are highly resistant to thermal-oxidative degradation. Dynamic thermogravimetric analysis showed that the temperature of decomposition in air is above 400°.

The synthesis and study of acid polyamides based on bis-ortho-amino acids and tetracarboxylic anhydrides☆

Acidic polyamides were synthesized, based on 4,4′-diamino-3,3′-dicarboxy-diphenylmethane (I) and on pyromellitic (II) and 3,3′,4,4′-benzophenonetetracarboxylic (III) acid dianhydrides. The influence of reaction temperature, total reactant concentration, their ratio and duration of the process on the reduced viscosity ηred of the acidic polyamide solutions was studied. The polymers obtained possess film forming capacity. Colourless, transparent, elastic films were obtained using (I) and (III).

Polymer based on 2,5-dicarbomethoxyterephthaloyl chloride and aromatic diaminodicarboxylic acids☆

A new type of polyamide containing ester and carboxyl groups, which are soluble in organic solvents, has been produced by low temperature polycondensation of aromatic diaminodicarboxylic acids having NH2 and COOH groups in ortho-position to each other (5,5-methylenedianthranylic and 3,3-benzidinedicarboxylic acids) with 2,5-di (carbomethoxy) terephthaloyl chloride. The effect of the polycondensation conditions on the reduced viscosity (the mol.wt.) of the polyamides has been investigated. Imidization of the polyamides, followed by ammonolysis of the polyimides and thermal cyclization of the polymeric ammonolyzate, yielded new heat resistant, heterocyclic, ladder-like polymers, i.e. the poly-isoindoloquinazolinediones. These polymers are not soluble in organic solvents and only dissolved with difficulty in concentrated sulphuric acid. According to the thermodynamic TGA in air, the start temperature of decomposition of the poly-isoindoloquinazolinediones is in the range 400–420°C. This range coincides also with the softening temperature.