细小颗粒物的传播对人体健康产生巨大威胁,而使用空气过滤材料是目前解决这一问题的重要手段。因此空气过滤材料在人们的日常生活中发挥着重要作用。聚丙烯熔喷无纺布材料已经大量应用于医疗卫生健康防护领域以及空气净化滤网,如PM2.5口罩、医疗一次性口罩以及HEPA( High Effciency Particulate Air Filter)、ULPA(Ultra Low Penetration Air Filter)材料。通常,为提升材料的过滤效率会降低纤维细度、提高纤维紧密度,然而材料的过滤阻力却大大增强。在空气过滤材料的研究发展过程中,过滤阻力与过滤效率一直是-对矛盾体。作为空气过滤材料必须要平衡二者之间的关系。驻极处理能够很好的解决过滤阻力与过滤效率之间的矛盾,使得过滤材料具有高效率、低阻力的更加卓越的过滤能力。驻极处理后的带电熔喷纤维网能够有效过滤空气中的亚微米颗粒物,减少可入肺颗粒物的散播。分别对聚丙烯熔喷驻极体过滤材料进行扫描电子显微镜、红外光谱测试、X射线光电子能谱测试、透气性等测试,分析电晕充电对聚丙烯熔喷材料产生的影响,为以后寻找提高驻极效果的方法打下基础。通过建立BP人工神经网络模型,分析工艺参数与驻极效果之间的相关性,并且通过参数预测性能。
In this work the authors have added an additional sensor to the traditional Phase Doppler Interferometry (PDI) configuration yielding three independent measures of phase shift between detectors. This seemingly minor enhance-ment has a profound impact on the limitations of the PDI technique in two important areas: the minimum laser beam diameters and the ability of the technique to discriminate liquid droplets from solid particles.Phase Doppler measurements can be impacted by reflection/refraction errors in which a droplet’s measured diameter is substantially different from its actual size. This is most critical when small droplets are measured as very large but the converse is possible as well. Consideration for this error source places a major constraint on the minimum laser beam diameter at the measurement volume. The addition of a third independent measure of phase shift effectively eliminates reflection/refraction errors allowing PDI measurements with smaller laser beams than would ordinarily be recommend-ed. The authors demonstrate this ability by measuring the same location of a spray with decreasing laser beam waists. Since the droplet number density limit of the Phase Doppler technique scales inverse to the square of the laser beam diameter, such an optical configuration would substantially enhance the instrument’s performance in dense sprays ap-plications.For applications such as icing cloud measurements, the ability to discriminate and size only liquid droplets in a mixed-phase environment is an important capability of the PDI technique. The relationship between the phase shifts of Phase Doppler signals can be used to differentiate liquid droplets or other spherical particles from irregularly-shaped solids. The authors demonstrate that the addition of a third independent measure of phase shift reduces the number of false positives (solids measuring as droplets) by a large factor – from 11.7% to 0.33% in one example.