ON THE CHARGE-STATE OF MELT-BLOWN POLYMER MATERIALS

Fibrous polymer materials formed by LDPE melt spraying with a gas flow during extrusion were exposed to thermally stimulated depolarization. The analysis of thermally stimulated current spectra and the sample c harge state has shown that the fibers possess the spontaneous polarizi ng charge. IR-spectroscopy has proved the material production to be ac companied by vinylene, vinyl, transvinylene and other nonsaturated gro ups formation. The latters are, probably, behaving as neutral trapping centers during their interaction with charge carriers formed at melt dispersion by the compressed gas flow and its contact with metal parts of equipment. The kinetics of these processes can be monitored by reg ulating technological regimes of fibrous material formation. Intensifi ed action on the polymer melt might rise the spontaneous polarizing ch arge whose density can reach 10(-10) to 10(-12) C/cm(2). Charge of the materials under study is rather stable. It does not fall below 40% up on a 160-days storage in humid atmosphere. It appears thus that the te chnique of fibrous material production by polymer melt spraying is an electret method.