SYNTHESIS AND PROPERTIES OF NEW POLYAMIDES BASED ON DIAMANTANE

A series of new polyamides was synthesized by direct polycondensation of 1,6-diamantanedicarboxylic acid (I) with various aromatic diamines in N-methyl-2-pyrrolidone (NMP) containing Lithium chloride. In this process, triphenyl phosphite and pyridine were used as condensing agents. High performance of direct polycondensation with triphenyl phosphite as a catalyst to I was subsequently obtained. The polyamides had inherent viscosities of 0.43-1.48 dL/g. Dynamic mechanical analysis revealed polymers IIIc and IIId to have main melting transitions at 400 and 374 degrees C, respectively. Moreover, these polymers were quite temperature stable and maintained good mechanical properties (G' similar to 10(8) Pa) up to temperatures close to the main transition well above 350 degrees C. A glass transition phenomenon, in the conventional sense, was not observed. Polyamide IIIc showed a melting transition with a sharp endothermic peak appearing at 412 degrees C. The 5% weight loss temperature was in the range 405-420 degrees C in a nitrogen atmosphere. Additionally, polyamides IIIc and IIId had tensile strengths of 82.9 and 62.3 MPa, elongations to break of 13.7 and 6%, and initial moduli of 1.4 and 1.6 GPa, respectively. Interestingly, compounds I and DMF formed a single crystal bonded with a hydrogen bond. The structure of I exhibits molecular symmetry.