The Preparation And Study On Properties Of Electret Polylactic Acid Meltblown Nonwovens

With the rapid development of industry, the air pollution became more and more serious.Air filter materials should have both high filtration efficiency and plastic pollution-free. Therewere some studies on Polypropylene (PP) meltblown nonwovens containing tourmaline andPolylactic acid (PLA) meltblown nonwovens.Hoever, the former was hardly to be degraded afterdiscarded, and the other had low filtration efficiency. Therefore, developing a type of electretPLA meltblown nonwovens was valuable to scholarship and market.A kind of modified PLA resin was prepared, by adding different doses of tourmaline andcoupling agent in this paper. The surface morphology, thermal properties and rheologicalbehavior were studied respectively. The result showed that the content of coupling agent were3%,3%and2%could match with1%,2%and3%, tourmaline content respectively.The spinnability of modified PLA resin was characterized by activation energy, structureviscosity index and crystallization rate. The mechanical properties, thermal properties ofundrawn and drawn fibers were tested, the changes of its melting points, crystallinity and degreeof orientation were studied.The optimal combination of the process parameters for PLA meltblown nonwovens waschosen by orthogonal experimental design. PLA meltblown nowovens were prepared underdifferent process parameters, such as extrusion velocity, hot air temperature, belt rate and die tocollect distance, etc. The surface morphology, pore size distribution, mechanical properties andair permeability were characterized, and the optimum parameters were10Hz,280℃,7.5Hz and25cm, respectively. As a result, PLA meltblown nonwovens with weight40g/m~2had highuniformity and the average diameter of fibers was6μm~8μm.The modified PLA meltblown nonwovens containing tourmaline were prepared under theoptimum technology parameters. The surface morphology, air permeability, pore size distribution,filter efficiency and attenuation of surface charge were researched. The results showed that thetourmaline dispersed densely on the surface of the fibers and the surface density of charge increased with the content of tourmaline increase. The surface charge density of the chargedmodified meltblown nonwoven with3wt%tourmaline increased, from13.7μC/m~2to19.4μC/m~2, and showed better persistence compared with that of pure PLA meltblown nonwovens.The filtration efficiency of the PLA meltblown nonwovens containing3wt%tourmaline was35%higher than that of pure PLA meltblown nonwovens and reached88.6%for particles with0.3μm~0.5μm diameter.