Viscosity polyimide materials

Table 1 lists some of the metal compounds employed and the results obtained when attempts were made to cast films of the resulting metal ion filled polyimide derived from BTDA + m,m -DABP. Brittle films were produced in most cases regardless of whether the added metal ion was hydrated or anhydrous. The relatively low viscosities of the resulting polyamic acid-metal ion solutions no doubt accounted for this. Addition of AlCl3 6H20 or any simple aluminium salt to the polyamic acid produced immediately a rubbery material that could not be cast into a film. 

Influence of Water on Heat Resistance. It is known that the viscosity of polyimide prepolymer (polyamic acid solution) is reduced by the absorption of a-small amount of water(2). This is because the absorbed water reduces the molecular weight by hydrolysis. Therefore, it seems probable that absorbed water would reduce the heat resistance of cured PIQ film. For that reason, the influence of water contained in the starting materials on the heat resistance of cured PIQ film was investigated. 

Figure 31.12 displays the desirable skin morphologies at various locations of dual-layer membranes. Briefly, both the inner and outer skins of the inner layer are porous with intimate adhesion between them. When using two different materials, one can control the interlayer diffusion as a function of spinning conditions. Table 31.2 summarizes the elemental analysis data of the interfacial layers of hollow fibers spun from PES as the inner layer and Matrimid polyimide as the outer layer at different spinneret temperatures (Jiang et al., 2004). After being extruded from the spinneret, the two dopes should make contact with each other under normal conditions. When the spinneret temperature is low (i.e., 25°C), their viscosities are high, the diffusion rate of the polymer molecules between the two layers will not be fast therefore, no sulfur can be found in the outer layer, as shown in this table. When the spinneret temperature is increased to 60°C, the interlayer diffusion between the two polymers apparently occurs, as evidenced in Table 31.2, in which it is... 

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