SYNTHESIS AND PROPERTIES OF LOW-THERMAL-E XPANSION POLYAMIC ESTERS

Polyamic acid esters (PAE) were synthesized from biphenyltetracarboxyl ic dialkylester dichlorides (alkyl group: methyl, ethyl, n-propyl, and n-butyl) and p-phenylenediamine (PDA). The weight-average molecular w eights (M(w)) ranged from 51000 to 60000. Solution viscosities of the polyamic eaters were lower than that of the polyamic acid (PAA) synthe sized from biphenyltetracarboxylic dianhydride (BPDA) and PDA. The val ues of elongation at break were 16 similar to 20% for all the films, a nd thermal expansion coefficients of the films ranged from 1.8 X 10(-5 )/K to 2.2 X 10(-5)/K. The values were larger than that of the polyimi de film (0.5 X 10(-5)/K) formed from the corresponding PAA.