Synthesis of Articulated All-Para Polymers
Abstract
Articulated all-para-polymers with 2,6-benzobisoxazole, 2,6- benzobisthiazole, and 2,6-benzobisimidazole units in the backbone were synthesized by copolycondensation in polyphosphoric acid of 4,6-diamino-1,3- benzenediol dihydrochloride, 2,5-diamino-1,4-benzenedithiol dihydrochloride, and 1,2,4,5-tetraaminobenzene tetrahydrochloride, respectively, with terephthalic acid and reactive diphenoxybenzene monomers. Inherent viscosities of up to 12.57 dL/g (CH3SO3H, 25 C, 0.2g/d1) were achieved. The average length of the rod-like all-para segments between the relatively flexible diphenoxybenzene units was controlled by the stoichiometry of the copolycondensation reactions. Films which exhibited optical birefringence under crossed polars could be cast from methanesulfonic acid solutions of the polymers. Modulus and tensile strength values as high as 4696 mPa and 93mPa, respectively, were recorded. Thermooxidative stability of the articulated polymers was evaluated by isothermal aging in air at 316 C. Stability for the articulated polybenzobisoxazoles was found to decrease with increased content of the diphenoxybenzene structure. The articulated polybenzobisoxazole structure was shown to be less stable than the anlogous polybenzobisthiazole structure but more stable than the articulated polybenzobisimidazole structure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1981
- Accession Number
- ADA107554
Entities
People
- F. E. Arnold
- R. C. Evers
- T. E. Helminiak
Organizations
- Wright Laboratory