Abstract

The properties and applications of polytetrafluoroethylene （PTFE） with high molecular weight were introduced. The factors that may influence the preparation of PTFE with high molecular weight such as the raw materials were introduced, based on the points of view including avoiding the slow down of polymerization speeds by avoiding the deactivation of growing free radicals and avoiding the reduction of relative molecular weight by avoiding the transfer of chains. It was suggested that the domestic research speed should be accelerated, multi-brand should be developed and the rely on importation should be got rid off.     

Abstract

The cross-sectional shape of FJCA jet flotation machine for coal was changed from inverted trapezoid to rectangular, cell depth thus increased , both height of froth and flotation zone elevated; cell width decreased, leading to reduction of horizontal moving distance of forth layer, even degree of aeration at cell bottom increased by times, and the perfection index of flotation remarkably upgraded.