Heterogeneous polyimide research is still in the initial stage, due to the experimental data accumulated enough wealth. So many laws can not be summed up quite sure, its physical meaning more needs to be further explored.
The isomeric dianhydride polyimide obtained by TG 3,3 '-> 3,4' - Order> 4,4 lowered. This is substituted in the 3-position of the phthalimide brought about the rotary receive obstruction.
Thermal stability between heterogeneous polyimide by the TG in the reverse order, I.e. 3,3 - <3,4 '- <4,4. This may be due to the 3-substituted phthalimide has a lower heat stability, and easier activities (lower TG) will consume more energy absorbed.
Since 3,4'-dianhydride obtained by other than a polyimide dianhydride isomers obtained polyimide has a much lower melt viscosity. This may be due to the asymmetric dianhydride polymer chains regularity poor, thus reducing the intermolecular force.
The m, m'- diamines polyimide polyimide smaller than p, p'- permittivity diamine. This is the m, m'- diamines polyimide For larger free volume.
Obtained from the isomeric diamine and dianhydride molecular chain is bent over the polyimide molecular chain relatively rigid polyimides having larger solubility.
The polyimide polymer ratio obtained by the 4,4'-dianhydride and 3,4'-3,3' anhydrides having greater selectivity and lower gas through, but an increase in permeability than selectively reduced to a large extent. And the p, p'- diamines polyimide gas separation factor greater permeability coefficient and slightly smaller.
For chiral aromatic polyimide matter failed to find significant differences in thermal stability, TG or solubility.