The present disclosure provides filters that can be removed from surfaces without damage by having reduced or eliminated contribution of a core backing to peel force generated by the adhesive during removal. In some instances, this can be accomplished by a core that loses structural integrity in a direction normal to a plane defined by a major surface. In other instances, the contribution is reduced by compromising the interface between the core and a peelable adhesive layer.

It is provided that an electret having excellent filtering performance and a filter using the electret even in a case where polyolefin resin and magnesium element are contained. An electret comprising a polyolefin resin and a nitrogen-containing compound, wherein 0.1 to 5 parts by mass of the nitrogen-containing compound is contained to 100 parts by mass of the polyolefin resin, a proportion of a magnesium element contained in the electret is 5 to 100 ppm, and a QF value represented by the following formula is not less than 1.00 mmAq.sup.−1 when particles having particle diameters of 0.3 to 0.5 μm are to be collected.

QF [mmAq.sup.−1]=— [1n (particle penetration (%)/100)]/[ventilation resistance (mmAq)]

Articles and methods relating to filter media are generally provided. In some embodiments, a filter media has an irregular surface structure. For instance, the filter media may comprise a plurality of peaks that are irregular in one or more ways. A ratio of a peak height standard deviation to an average peak height may be greater than or equal to 0.05, and/or a ratio of a peak spacing standard deviation to an average peak spacing may be greater than or equal to 0.08. In some embodiments, a filter media comprises a non-woven fiber web having a layer thickness of greater than 0.3 mm and/or a stiffness of less than or equal to 100 mg.

Articles and methods relating to filter media are generally provided. In some embodiments, a filter media has an irregular surface structure. For instance, the filter media may comprise a plurality of peaks that are irregular in one or more ways. A ratio of a peak height standard deviation to an average peak height may be greater than or equal to 0.05, and/or a ratio of a peak spacing standard deviation to an average peak spacing may be greater than or equal to 0.08. In some embodiments, a filter media comprises a non-woven fiber web having a layer thickness of greater than 0.3 mm and/or a stiffness of less than or equal to 100 mg.

Non-woven fiber webs and articles (e.g., filter media) comprising non-woven fiber webs are generally described. In some embodiments, a non-woven fiber web described herein formed via certain non-wetlaid processes may exhibit enhanced physical properties. For example, a non-woven fiber web may be subjected to a carding (e.g., cross-lapped carding) process. In some cases, the non-woven fiber webs described herein may be calendered to further enhance their physical properties.

The present disclosure provides a flow-through aerosol capture device that includes a chamber defining an airflow path, and at least one heat-stable aerogel filter, for example a heat-stable polymer aerogel filter, disposed in the airflow path for capturing aerosol particles when an aerosol-containing gas passes through the filter. The flow-through aerosol capture device may be a needle-trap device or a thermal desorption liner with a heat-stable aerogel filter in the lumen of the needle or the liner. The disclosure also provides heat-stable polymer aerogels and methods of making such aerogels.

A method for controlling fiber cross-alignment in a nanofiber membrane, comprising: providing a multiple segment collector in an electrospinning device including a first and second segment electrically isolated from an intermediate segment positioned between the first and second segment, collectively presenting a cylindrical structure, rotating the cylindrical structure around a longitudinal axis proximate to an electrically charged fiber emitter; electrically grounding or charging edge conductors circumferentially resident on the first and second segment, maintaining intermediate collector electrically neutral; dispensing electrospun fiber toward the collector, the fiber attaching to edge conductors and spanning the separation space between edge conductors; attracting electrospun fiber attached to the edge conductors to the surface of the cylindrical structure, forming a first fiber layer; increasing or decreasing rotation speed of the cylindrical structure to alter the angular cross-alignment relationship between aligned nanofibers in adjacent layers, the rotation speed being altered to achieve a target relational angle.

Intra-nasal filter devices and methods for their manufacture and use are disclosed. An intra-nasal filter device includes: a first stage filter proximate the septum; and a second stage filter comprising a flexible material extending upwardly from the first filter stage filter; wherein the flexible material comprises: an impedance in the range of 0.02 to 0.2 cmH.sub.2O; an effective cross-sectional area in the range of 0.2 to 2 square inches; and a plurality of radially extending geometric structures disposed along an axial length of the second stage.

Reusable filters for personal protective equipment (PPE) may prevent shortages of PPE and save fabrication time, resources, and money. Disclosed is a method and system for fabrication of nanofiber filter media for PPE. The method includes positioning a substrate to receive nanofibers thereon, providing a voltage gradient in a region of the substrate, and electrospinning nanofibers onto the substrate. The methods and associated systems allow autoclaving of the filter medium at temperatures of up to 300 degrees for sanitizing the filter medium. Additionally, the methods and associated system allow for the inclusion of an anti-pathogen agent in the nanofiber filter media.

Filter media comprising a pre-filter layer and related components, systems, and methods associated therewith are provided. In some embodiments, the pre-filter layer may be designed to impart desirable properties to the filter media, such as a high gamma and/or long service life, while having relatively minimal or no adverse effects on another property of the filter media that is important for a given application. For instance, a pre-filter layer may be used to improve the upstream removal of fine particulate matter, which may clog a downstream efficiency layer comprising submicron fibers and reduce filtration performance. The pre-filter layer may be configured to increase service life and/or increase the gamma of the filter media. Filter media, as described herein, may be particularly well-suited for applications that involve filtering air, though the media may also be used in other applications.