Design of electret polypropylene melt blown air filtration material containing nucleating agent for effective PM2.5 capture

Particulate matter (PM) pollution has become a serious threat to public health, climate and ecosystems. Therefore, filtration materials with high filtration efficiency and low air resistance are in urgent need. Electret filters that can significantly improve filtration efficiency without increasing pressure drop are widely used for air filtration. However, long-term maintenance of the electrical charges on electret filters, particularly at high temperatures and in wet conditions, is still a challenge. Herein, we report the fabrication of a novel electret filter with a fluffy structure, high porosity and satisfactory filtration stability using polypropylene (PP) as the matrix polymer and magnesium stearate (MgSt) as the charge enhancer. Benefiting from the fluffy structure created by melt blown at a large die-to-collector distance (DCD), the pressure drop decreased from 67.0 Pa to 52.9 Pa at an air flow rate of 85 L min(−1). Furthermore, the introduction of MgSt changed the crystal structure of the melt blown nonwovens, thus improving the electret properties to achieve a high filtration efficiency of 99.22%, a low pressure drop of 92 Pa and a satisfactory QF of 0.054 Pa(−1). In particular, the electret filtration materials exhibited excellent filtration stability and loading performance. Thus, this electret material may become a good candidate for personal protective filtration materials against PM2.5.