Reactive mixing power requirements

The presence of two methyl groups in m-xylene makes it a more reactive substrate than toluene, but as a consequence, this substrate is more susceptible to oxidation. Therefore, the nitration of m-xylene requires lower temperatures and the use of less concentrated mixed acid. In fact, the nitration of either 2,4- or 2,6-dinitro-m-xylenes to 2,4,6-trinitroxylene (TNX) can be achieved with mixed acid containing up to 10 % water. TNX is a less powerful explosive than TNT and has a poor oxygen balance (—78.4 %). 

The present tendency in CORl development is to (1) maximize throughput from the given size machine by maximization of the extruder free volume or the OD/ID screw ratio, (2) provide capability to efficiently transmit the required amount of power into the material, and (3) increase the extruder speeds. The modem machines from Werner Pfleiderer are supplied with OD/ID = 1.55, those from Berstorff with 1.74 (for reactive compounding and degassing). The latter company also developed several mixing elements turbo or gear mixers) well suited for mixing resins with different viscosities. Smaller industrial CORl machines are available from JSW with the screw speed of N < 1,500 rpm. Similar speeds are also offered... 

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