Alicyclic Polyimides based on bicyclo[2.2.1]heptane- 2,3,5,6-tetracarboxylic 2,3-5,6-dianhydrides

• Published in: High performance polymers 2006-10, Vol.18 (5), p.719-726
• Main Authors: Matsumoto, Toshihiko, Kawabata, Shuichi, Takahashi, Risa
• Format: Article
• Language: English
• ISSN: 0954-0083; 1361-6412
• DOI: 10.1177/0954008306068245

The alicyclic polyimides were prepared by reacting bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic-2,3-5,6-dianhydride (BHDA) with aliphatic or aromatic diamines in hexamethylphosphoramide. The poly(amic acid)s possessed inherent viscosities (νinh)in the range from 0.13 to 0.38, and they formed free-standing and flexible films after being cast then cured. The fully alicyclic polyimide films exhibited a cutoff around 230 nm, and are transparent even in the near infrared region. The optically estimated ε of the fully alicyclic polyimides was about 2.6. All the alicyclic polyimide possessed negligibly small birefringence below 10-4. Semi-aromatic polyimide PI(BHDA + 1,3-BAB) had good thermal stability with no significant weight loss up to 350°C, and the T 5 was around 450°C, although the T g was as low as 197°C. All polyimides exhibited broad dispersive peaks of diffraction around 16° (2τ). The PI(BHDA + BBH) film possessed a tensile modulus of 2.05 GPa and a tensile strength of 52 MPa, and these values can compete in terms of strength with those of a commercial polycarbonate.