Study on correlation between charge storage and filtration performance of melt-blown polylactic acid/polyvinylidene fluoride electret air filter materials
Objective Under the background of the continuous aggravation of air particulate matter pollution,in order to achieve efficient filtration of PM2.5 and other harmful particulate matters in the air to achieve the purpose of protecting human life and health,polyvinylidene fluoride(PVDF)with good dielectric and polarity was compounded with biodegradable polylactic acid(PLA),so as to prepare an environmentally friendly electret air filter material with fine fiber diameter,small pore size,high filtration efficiency and low filtration resistance.And the influence of PVDF on the crystallization behavior,charge storage performance and the relationship between the mechanism and filtration performance of PLA corona electret air filtration material was investigated.Method The melt-blown nonwovens were prepared by melt blending with PLA as the substrate and PVDF as the electret additive material.The convenient and efficient corona electret process was adopted to greatly improve the filtration efficiency of the prepared PLA/PVDF melt-blown nonwovens of through electrostatic adsorption without increasing the filtration resistance.The influence of PVDF on the crystal structure of PLA and the change of crystallinity were studied by X-ray diffractometer.The influence of PVDF on the crystallization process of PLA was studied by hot stage polarizing microscope,and the charge storage performance was studied by thermally stimulated discharge tester.Results By introducing an appropriate amount of PVDF(PLA/0.3%PVDF melt-blown nonwovens),the melt-blown nonwovens fiber is more uniform,the fiber network structure is more dense,the pores are more,the pore size is smaller,and the diameter is finer to 2.60 μm.It was found by X-ray diffractometer that the introduction of PVDF made the crystallization of PLA more orderly.The crystallinity of PLA/0.3%PVDF melt-blown fabric was the highest,reaching 16.99%.It was found by hot stage polarizing microscope that the introduction of PVDF significantly accelerated the crystallization rate of PLA.The test results of surface electrostatic meter and thermal stimulation discharge instrument show that the electrostatic potential of PLA/0.3%PVDF melt-blown nonwovens after corona electret can reach more than 3 kV,the peak value of TSD is higher,and the charge storage capacity is significantly improved.It shows that the introduction of PVDF can improve the crystallization properties of PLA and promote the crystallization process of PLA,thereby increasing the charge storage position during corona electret.The filtration efficiency of PLA/0.3%PVDF single-layer melt-blown nonwovens after corona electret reached 85%,and the filtration resistance was less than 40 Pa.Compared with the filtration efficiency of the corona electret melt-blown nonwovens without PVDF,the filtration efficiency was increased by more than 20%.The quality factor was used for comprehensively measuring the effect of air filter materials.It was found that the quality factor of PLA/0.3%PVDF melt-blown nonwovens after corona electret was higher than that of non-electret melt-blown nonwovens from less than 0.01 Pa-1 to 0.046 Pa-1.The filtration efficiency of PLA/0.3%PVDF melt-blown nonwovens decreased from 98%to 80%when the air flow rate increased from 10 L/min to 90 L/min,with the smallest decrease.It is further illustrated that the corona electret melt-blown nonwovens with an appropriate amount of PVDF has the best overall filtration performance.Conclusion By systematically studying the relationship between the crystallization behavior,charge storage performance and filtration performance of PVDF on PLA corona electret air filter material,it is found that the introduction of PVDF has an important influence on the crystallization performance of PLA/PVDF melt-blown nonwovens.The introduction of PVDF accelerates the crystallization rate of PLA and increases the crystallinity,which leads to the improvement of charge storage performance of PLA/PVDF melt-blown nonwovens and finally improves the filtration performance.The prepared degradable high-efficiency electret air filter material can effectively cope with the increasingly severe air pollution and the continuous virus prevention and control.
air filtration materialelectretmelt-blowncorona electretpolylactic acidpolyvinylidene fluoride
NETL
NSTL
万方数据
