Molecular weight polyimide materials

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. 

The variety of ways in which chloral and trinitrotoluene (TNT) derivatives can be used to prepare novel polyimides and polymeric materials is very promising. The use of chloral and TNT derivatives allows for the synthesis of a large number of monomers which, in turn, can impart a variety of useful properties to their respective polymers. The possibility of preparing, from available raw materials, high-molecular-weight compounds with increased heat and thermal resistance in combination with improved solubility and, consequently, easiness of processing is especially attractive and may provide impetus for further work in this field. 

The use of static SIMS for the characterization of surfaces of polypropylene (PP), PTFE and a PMDA-ODA type poly-imide is described. Interfaces between evaporated copper or chromium films onto PTFE and polyimide were also analyzed. Some of the polymer substrates were modified by ion beams, corona discharge in air or plasma treatments in air, At and H2. It is demonstrated that SIMS is highly complementary to XPS for the analysis of such modified surfaces, in that effects such as crosslinking, unsaturation and formation of low-molecular weight material at surfaces can be detected. 

Another method for solubilizing polyimide film by curing the polyamic acid for longer times at lower temperatures was attempted. The 6F + 4,4 -ODA film cured 1 hour at 300°C was found to be insoluble in DMAc at ambient temperature. Hie same material cured for 5 hours at 200 C was totally soluble in DMAc upon stirring for several hours. Hie enhanced solubility of this polymer could be due to a possible lowering in molecular weight or incomplete imidization of the polyamic acid. Hiis method for obtaining solubility is not a preferred method but is mentioned... 

Polyimides for use in electronics must be carefully selected and prepared to produce consistent materials with the desired properties. Furthermore, the impact of polymer processing on the circuitry must be carefully considered. In particular, the molecular weight of the polyimide resin must be controlled for successful application and imaging, which means that the molecular weight of the precursor polyamic acid must be controlled. 

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