This study examined the moisture absorption and other properties of nylon-6,6

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The effect of carbon black on mechanical properties of polycarbonate and polycarbonate-polypropylene blends was investigated. Experimental work included compounding with a single screw extruder, injection molding of test specimens, and evaluation of the blends physical properties using standard testing instruments. The results showed that carbon black increased tensile strength, tensile modulus, and flexural modulus. However, it decreased elongation at break, impact strength, and toughness. The increase of polypropylene concentration in the blends decreased their tensile strength, tensile modulus, elongation at break, impact strength, and toughness. The effects of polypropylene on tensile modulus and strength were discussed using a model containing a continuous polycarbonate phase enriched by carbon black and polypropylene minor phase with little interfacial interaction between two polymers. Values of the impact strength and the toughness of blends with different compositions were found to correlate by one curve.

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Water absorption at 93 % relative humidity and 25°C was determined for 12 regular aliphatic/aromatic copolyoxamides. The equilibrium water absorption ranges from 7 % to 30%, varied with the polymer structure and is highest in polymers with high amide concentration. The water absorption is reversible and seems to consist of a two-step process, rapid absorption of water by polymer followed by a slower second stage as equilibrium is approached. These polymers have low crystallinity and the water absorption does not occur in crystalline regions. All water is bound to the polymer; it may be freed by heating the hydrated polymer above 100°C, but rebinds completely at room temperature. a) Part 6 : ~f . '~) . *) Systematic name: poly(iminooxalyliminoethy1eneiminoisoterephthaloyliminoethylene)' 'I.