Rheological behaviour of polyamic acid spinning solutions containing heterocycle

The rheological behaviour of polyamic acid (PAA) solution was studied using N,N-dimethylacetamide (DMAc) as a solvent. The results showed that the PAA/DMAc solution with solid contents of 11–15 wt-% was a shear-thinning fluid. The non-Newtonian behaviour of the solution increased with increasing PAA concentration and decreasing temperature. The complex viscosity (η*) increases upon the concentration of PAA solution. Storage modulus and loss modulus increase with increasing frequency and an obvious plateau modulus appears, exhibiting a typical solid-like behaviour at high frequencies. The PAA solution with higher solid content shows lower tangent loss angle (tan δ), higher storage modulus and loss modulus. Increasing temperature plays an opposite role in increasing polymer concentration on complex viscosity, storage modulus, loss modulus and tan δ.