The following articles were authored by drtel

Liquid Extrusion Porosimetry and the Measurement of Pore Size and Volume in Nonwovens

Nonwoven fabric is the name given to fabric-like materials that are made from long fibers (continuous long) and staple fiber (short) bonded together by mechanical treatment, heat, solvent or other chemical application. This method of production distinguishes non-woven materials from woven and knitted fabrics. Fibres may be oriented in one direction or deposited randomly to produce one or more fibre layers. The resulting products are flexible and porous. Felt is probably the most commonly known nonwoven material but the term also includes plastics like nonwoven polypropylene. A variety of manufacturing processes can be used, including spunlaid, staple nonwoven, flashspun and airlaid paper, to produce nonwovens.

Nonwovens have many applications in a wide variety of industries such as healthcare, biotechnology, paper, filtration as well as household uses. When in use they are subjected to compressive stress and the performance of nonwovens in such applications is largely determined by their pore structure. In order to assess this vital property it is important to characterise pore size, pore volume and pore volume distribution of nonwovens under compressive stress.nonwoven

The development of instruments that can measure such pore structure characteristics became a priority in the field and research developed the use liquid extrusion porosimetry to measure pore volume and pore diameter of a nonwoven under compressive stresses. The method uses a wetting agent, a liquid that can spontaneously flow into the pores of a sample. This is possible because the solid/wetting liquid interfacial free energy is less than the solid/gas interfacial free energy. Filling of the pores of the nonwoven sample with the wetting liquid therefore reduces the free energy of the system.

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Liquid-Liquid Porometry for Characterising Ultrafiltration Membrane Pores

Liquid-Liquid Porometry (LLP) is a valuable technique for measuring the pore structure characteristics of ultrafiltration membranes without damaging the membranes themselves. These membranes can act as barriers to a whole range of particles, both organic and inorganic, including bacteria, pollens, spores, pathogens and pesticides and even high molecular weight solutes, colloidal suspensions, and viruses.

Pore characteristics such as pore distribution, liquid permeability, pore throat diameter, bubble point pore diameter and mean flowpore diameter all offer valuable insights into pore function. However, capillary flowporometry a technique that can provide the required information about such characteristics uses high test pressures not suited for measuring ultrafiltration membranes. Liquid-Liquid Porometry (LLP) by comparison can measure the required pore structure characteristics without distorting the pore structure or damaging the membranes. In addition LLP is faster, uses less energy and lower pore sizes can be characterised.poro fror blog

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