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 p rocess, triphenyl phosphite and pyridine were used as condensing agent s. High performance of direct polycondensation with triphenyl phosphit e as a catalyst to I was subsequently obtained. The polyamides had inh erent viscosities of 0.43-1.48 dL/g. Dynamic mechanical analysis revea led polymers IIIc and IIId to have main melting transitions at 400 and 374 degrees C, respectively. Moreover, these polymers were quite temp erature stable and maintained good mechanical properties (G' similar t o 10(8) Pa) up to temperatures close to the main transition well above 350 degrees C. A glass transition phenomenon, in the conventional sen se, was not observed. Polyamide IIIc showed a melting transition with a sharp endothermic peak appearing at 412 degrees C. The 5% weight los s temperature was in the range 405-420 degrees C in a nitrogen atmosph ere. Additionally, polyamides IIIc and IIId had tensile strengths of 8 2.9 and 62.3 MPa, elongations to break of 13.7 and 6%, and initial mod uli of 1.4 and 1.6 GPa, respectively. Interestingly, compounds I and D MF formed a single crystal bonded with a hydrogen bond. The structure of I exhibits molecular symmetry.