High-modulus poly(p-phenylenepyromellitimide) films obtained using a novel gel-drawing technique - Polyimides and Other High Temperature Polymers - page 160

Figure 8. Comparison of gel-drawn PPPI film with commercial heat-resistant films.
The performance of gel-drawn PPPI film is compared with commercially avail-
able heat-resistant polymer films in Figure 8 from the viewpoint of thermal and
mechanical properties. Here thermal degradation temperature (T d ) represents the
temperature at which 5% weight loss has occurred in thermo-gravimetric analysis.
One can see that the gel-drawn PPPI film possesses both the highest Young's
Modulus and the highest T d .
5. CONCLUSION
The PPPI was once discarded because of its intractable nature. Novel technique of
gel-drawing overcomes the earlier problems. The breakthrough is based on choos-
ing a special polyisoimide precursor and designing highly swollen gel structure.
Gel-drawing induces highly planar orientation of polymer chains with restricted
lateral crystal growth, which results in much improved tensile strength and high
Young's modulus.