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The electrical resistivity of the tetracyanoquinodimethane salts of ten alkali and transition metal cations has been investigated at temperatures from 300 to 470 K. The measurements indicate a phase transition, the activation energy of conductance being smaller in the high temperature region. The nature of this phase transition is discussed.

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In reactor irradiated aniline or pyridine most of the radiocarbon generated by the 14N(n,p)14C reaction was found preferentially localized in a polymer-like material, brown in color, frequently lustrous and constituting 15-30% of the initial amount of the irradiated material. This stimulated us t o try to obtain an idea about the chemical groupings existing in these highly radioactive materials a n d thereafter to deduce their possible formation pathways.By comparing the i.r. spectra of these polymers with those of the corresponding pure compounds it was possible to detect some changes in the spectra on polymerization and consequently it was possible t o identify some basic structural groups existing. Based on these findings some polymerization reaction mechanisms have been suggested. In general, polymer formation was assumed to take place through the formation of polymerization centers produced by the rupture of the aromatic rings to give highly unsaturated fragments and radicals. These are capable of adding different radicals and fragments formed in the irradiated material by radiolysis or by the action of energetic recoil atoms. Cross linking between individual polymer chains was observed. The preferential localisation of 14C in the polymer fraction could be attributed to the great capacity of the recoil atoms to form reactive secondary species such as 14CH3', 14CH2", or 1 4 C H which participate in polymer formation.L'aniline ou la pyridine irradiee dans un rkacteur oh la majorit6 des radiocarbones produits provient de la reaction L4N(n,p)'4C, se retrouve priferentiellement, comme il a kt6 trouve, sous forme d'un produit du type polymere, de couleur brunltre souvent reluisant et comportant 15-30% de la quantitt initiale du materiel irradie. Cette constatation nous a alors amene a rechercher les diffkrents groupements chimiques present dans ces produits hautement radioactifs et par suite i en deduire les differentes voies possibles de formation.En comparant les spectres i.r. de ces polymeres avec ceux des esptces pures correspondantes, il fut possible de deceler certains changements dans les spectres a la suite de la polymerisation e t par suite il fut possible d'identifier quelques groupes structuraux presents. En se basant sur ces donnees, quelques mecanismes de reactions de polymerisation furent entrevues. En general, la formation des polymeres semble se produire i la suite de la formation de centres de polymerisation dkcoulant d e la rupture des cycles aromatiques pour donner des fragments hautement insatures ainsi que des radicaux. Ceux-ci sont capables d'additionner differents radicaux et diffkrents fragments formks dans le matkriel irradie par radiolyse ou ti la suite de I'action d'atomes trts energetiques. On a aussi observe la formation de ponts entre differentes chaines polymeriques individuelles. On a attribue la localisation preftrentielle du 14C dans la fraction contenant le polymtre a la grande facilitk des atomes energetiques i former des esptces reactives secondaires telles 14CH3., l4CH2-ou " ...

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