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Polypropylene (PP) melt-blown electret webs were melt-spun by melt-blown processing of PP and PP/filler composites. The effect of tourmaline particles on the structure, morphology, and mechanical properties of PP melt-blown webs is reported. The meltblown webs were characterized by differential scanning calorimetry, wide-angle x-ray diffraction, scanning electron microscopy (SEM), and pore size meter. The crystallinity of melt-blown webs with tourmaline particles was more than that of PP alone. SEM micrographs revealed good dispersion of the additive in the fiber webs. The tourmaline particles offered some benefits to the mechanical properties of the melt-blown web. Melt-blown web samples with tourmaline had larger pore size, high surface charge density, higher filtration efficiency and stability of filtration efficiency.

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The current research status and development trends are summarized in order to analyze the strain softening deformation characteristics of post-peak of rocks, and the corresponding key problems are found, the key issues included the influence of strain softening on tunnel engineering and the research status of strain softening in hydraulic engineering. Based on the existing researches, it is found that there are few studies on the deformation characteristics of post-peak of rocks, and there is a lack of damage constitutive model which can better describe the post-peak mechanical properties. At present, it is impossible to simulate the influence of rock softening on stiffness degradation in indoor tests, and there is also a lack of on-site construction measured data as support; at the same time, the surrounding rock control and protection technology under loading and unloading also urgently needs to be improved; in addition, the interaction mechanism between water and structure during rock softening with water needs to be further explored.

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