Abstract: An improved synthesis for PMR-type polyimides, including first preparing a dimer of 5-norbornene-2,3-dicarboxylic acid, or acid ester or anhydride and 4,4'methylenedianiline. This dimer is then reacted with the reaction product of the dimethyl ester (or dianhydride) of 3,3', 4,4'-benzophenonetetracarboxylic acid and 4,4'-methylenedianiline. The resulting polyimide prepolymer exhibits superior physical properties and is substantially free of the undesired trimer of 5-norbornene-2,3-dicarboxylic acid, or acid ester or anhydride and 4,4'-methylenedianiline. When this dimer is reacted with 3,3', 4,4'-benzophenonetetracarboxylic acid dianhydride methylenedianiline amic acid mixture, the resulting polyimide prepolymer exhibits superior physical properties.

Abstract: An improved synthesis for PMR-type polyimides, including first preparing a dimer of 5-norbornene-2,3-dicarboxylic acid, or acid ester or anhydride and 4,4'methylene dianiline. This dimer is then reacted with one of the following:1. the reaction product of a primary aromatic diamine and an aromatic dianhydride.2. an aromatic dianhydride.3. a mixture of a primary aromatic diamine and an aromatic dianhydride, or an ester of an aromatic tetraacid or an aromatic tetraacid.The resulting polyimide prepolymer exhibits superior physical properties and is substantially free of undesired impurities and unreacted 4,4'-methylene dianiline.

Abstract: An improved balanced fishing rod is disclosed having line-tension-responsive indicating means operable to produce a visual indication when tension on the fishing line exceeds a predetermined value. The indicating means includes a rechargeable direct-current voltage source having a pair of terminals sealed to the fishing rod, a charging diode enabling the voltage source to be recharged while remaining sealed to said fishing rod, and a light-emitting diode connected in parallel with the charging diode. The charging diode is reversely positioned with respect to the light-emitting diode so that an electric current emanating from the voltage source will pass through and light the light-emitting diode and not pass through the charging diode, while an electric current emanating from a charging battery will pass through the charging diode and not the light-emitting diode to recharge the voltage source without lighting the light-emitting diode.

Abstract: Elastomeric butadiene-piperylene copolymers in which the butadiene is mainly in high cis-1,4-addition, low vinyl configuration, prepared in solution using iodine-containing catalyst based on organomagnesium compound and titanium tetrahalide. Graft copolymers of resin-forming monomers (e.g., styrene, acrylonitrile) on the butadiene-piperylene elastomer have good low temperature impact strength.