Experimental Dry Mixing Technique

Parnell has proposed to dry mix MTV to overcome the problems associated with highly flammable solvents acetone and hexane [12]. For this purpose, ground Viton was obtained as premix with Teflon from Dupont (Viton actually behaves Hke a highly viscous liquid thus ground particles coalesce after a short period of storage). The actual mixing process is carried out in a combined screw feeder and mixer that opens feeds into a mold or extruder to give the final shape. Table 18.3 compares 

Sample Compressive strength (kPa X 10 ) Strength at maximum stress (cm- ) Toughness (kPa m ) 

The dry mixed compositions burn faster than the wet mixed compositions because of significant higher grain porosity (Table 18.4). This also effects a lower spectral efficiency because of shorter residence time of Mg particles in the hot flame and thus less complete bum out. Dry mixing was never reahzed on a larger scale. 

Composition 5(dry) has a reported resistance of 4 x 10 Ohm and a conductivity of 1.5 X 10 S cm [12]. Another experimental dry mixing technique was used to prepare an Mg/PTFE-based flash mixture [13]. 

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