Preparation and properties of nano-SiO₂ electret/PLA composite meltblown nonwovens

A kind of nano-SiO₂/PLA meltblown chip, composited with the surface modified nano-SiO₂ electret and PLA resin, was prepared by two-screw extruder. After meltblown manufacturing, the nano-SiO₂/PLA compo-site meltblown nonwovens were obtained. FTIR testing was used to evaluate the effect of surface modification of nano-SiO₂. DSC testing was used to investigate the crystallinity of nano-SiO₂/PLA meltblown chips at fast cooling process like melt-blowing. Filter media testing platform and SEM testing were used to investigate the filtration property and micromorphology of the nano-SiO₂/PLA composite meltblown nonwovens respectively. The mass loss method was used to evaluate the degradation property of the nano-SiO₂/PLA composite meltblown nonwovens in the end. The results show that after modification the surface of nano-SiO₂ has been covered with organic functional groups. At 100℃/min cooling rate, the crystallinity of neat PLA is quite low while adding nano-SiO₂ electret can remarkably improve it. A small amount addition of nano-SiO₂ electret can notably enhance the filtration efficiency of PLA composite meltblown nonwovens, as the composite with 0.75 wt% nano-SiO₂ has a high filtration efficiency of 99.69%, which is close to the commercialized high efficiency particulate air filter (HEPA) level PP product. The nano-SiO₂/PLA composite meltblown nonwovens are degradable at neutral hydrolysis condition, of which the mass drop to 79.57% after 8 months degrading.