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Everything about Filters

1. Technical  specifications

 

During the manufacture of the filter, the non-woven fabric with a one-sided nanofiber layer is cut into a rectangle of 20 x 30 cm and folded in half until the final dimension of 20 x 15 l.

1.1 Technical specifications of the Nanofiber filter

The nanofiber filter is technically specified by the material parameters and work procedures indicated here.

 

A spunbonded nonwoven is coated by an alternating electric spinning method (AC Elekcrospinning) or by the DC Electrospinning method (NANOSPIDER device) with a layer of polyvinylbutyral nanofibers (PVB). Polyvinyl butyral is dissolved in technical alcohol for the production of nanofibers. The grammage resulting from the nanofibers layer is 1-1.5 g / m 2.The basic dimensions of the filter are 15 x 20 cm. the weight of a filter comprising two layers of spunbond is 1 to 1.5 g with filter in particular, it is necessary to avoid shearing of the outer layers of spunbond. Cm ,subsequently, the filter is ultrasonically welded on three sides (outside the lintel side) or cut and laser welded to avoid damaging the inner layer of nanofibers by handling.

Fig1: structure et dimension nanomaterial

The spunbond used for the production of filters is made of polypropylene and polyethylene.

The nanofibrous layer is made of polyvinyl butyral (PVB) at the Technical University of Liberec using the AC electrospinning method.

Tab1 : Materials used for the production of disposable nanofiber filter.

1.2 Strukture of nanofiber

Nanofibrous filter consists in folding a layer of blue / white spubond nonwoven fabric on which four nanofibrous layers are applied by the AC electrospinning method or a comparable base weight layer by the DC electrospinning method (NANOSPIDER device) . The composition results in a formation having on the surface of a blue / white spun bonding layer containing six / eight layers of nanofibers. The filter is inserted into a pocket mask. The adherence of the drape to the face around the nose is ensured by a folded connecting wire (adapted to the shape of the wearer's nose) sewn into the top of the drape. A drape threaded through the sleeve on the sides of the drape is used to secure the drape.

Fig2:  Nanomaterial by  SEM

Fig3: SMS Comparaison des diamètres de fibres non tissés et de nanofibres

1.3 Stérilisation - décontamination  filter   nanofiber

The filter is partially / incompletely sterilized by exposing the filter to a high air temperature 60C for 1 hour in a chemical oven. Higher temperatures are excluded due to the precipitation of the spunbond layers.

1.4 Properties of the filter nanofiber mask

The filtration properties, the degree of crystallinity and the wettability of the nanofiber filter and of its selected components were measured.

2. most penetrating particle size method

 

The tests carried out by the most penetrating particle size method show a highly non-linear dependence of the filtration efficiency and of the particle pressure drop of 100 nm on the speed of production of the nanofiber filter layer by the AC Electrospinning method. The tests were conducted by the kindness of Vladimír Ždímal, Ph.D., head of the Department of Chemistry and Aerosol Physics, Institute of Fundamental Principles of Chemical Processes at CAS. A satisfactory filtration probability is obtained at production speeds of nanofiber layers using the AC Elektrospinning method from 2 to 3.5 m / min.

Fig4: Electrospinning & particule  NANO

Capture the efficiency of particles with a characteristic size of 100 nm on the production speed of the pilot line for the production of nanofibrous material by the AC electrospinning method. For clarity of dependence, the experimental points are interspersed with a smooth curve. Measured - Vladimir Ždímal, Ph.D., Head of the Department of Aerosol Chemistry and Physics, Institute for Fundamental Principles of Chemical Processes

Fig5:Chute pression

Dependence of the pressure drop on the nanofiber filter at a flow rate of 10 m / min on the production speed of the pilot line for the production of nanofibrous material by the AC electrospinning method. For clarity of dependence, the experimental points are interspersed with a smooth curve. Measured - Vladimir Ždímal, Ph.D., Head, Department of Chemistry and Aerosol Physics, Institute of Fundamental Chemical Processes.

Fig6: Relation vitessse m/mn  a efficience  filtration

After adjustment of the laboratory line AC-Dependence on the capture efficiency of particles of characteristic size 100 nm on the production speed of the pilot line for the production of nanofibrous material by the AC electrospinning method. For clarity of dependence, the experimental points are interspersed with a smooth curve. Measured - J.Hrůza TUL, March 30, 2020.

3. description of the method

 

The method measures the properties of highly efficient particulate air filters. The measurement makes it possible to determine the particle size distribution and the capture efficiency of the "worst particles". Solids (NaCl, KCl ...) or liquids (DEHS ...) can be used as test particles. Mainly, the method is designed to determine the initial characteristics of filtration, under certain conditions, it is possible to test their evolution over time.

Fig7: Mesure by MFP 1000 HEPA

Fig8: Mesure  aerosol

Filtration efficiency values determined by the DEHS (Di-Ethyl-Hexyl-Sebacat) aerosol measurement method as a function of the particle size for the nanofiber filter produced by the AC Electrospinning method at a production speed of 3, 5 m / min. (J. Hruza and M. Komarek, TUL).

4. test cristanility degree pvb

 

Polyvinylbutyral (PVB), a polymer for the production of nanofibers, Movital B 60 H, manufactured by Kuraray, was measured by differential scanning calorimetry (DSC). The measurements showed that the polymer in the form of nanofibers is mainly in the amorphous phase.

Degree of crystallinity of PVB

Fig9:  Image  DSC

Differential scanning calorimetry (DSC) - (red) DSC has produced nanofibers. The polymer is amorphous with a glass transition temperature of 70 ° C. The curve is for the second heating cycle. (black) Polyvinylbutyral, polymer for the production of nanofibers, Movital B 60 H, the producer Kuraray is the raw material for the production. The curve corresponds to the first heating cycle.

5. technical specifications of cotton pocket curtains

 

A reusable pocket sheet, such as cotton fabric, is used to insert a filter disposable nanofiber. It facilitates decontamination of the nanofiber filter.

Tab2 : Configuration cotton for decontamination nanofilter