As to measurements of filtration effectivity and vapour permeability, you refer to EN and ISO standards. Can you for us, who are not familiar with them, shortly specify the conditions (membrane area and thic...Zobraziť celý komentárkenss, flow rate, or whatever is relevant)?

Concerning to water permeability: The vapour permeability was measured using the PERMETEST Sensora Skin Model (experimental device was developed by Prof. Hes, TUL). The device provides measurements required ...Zobraziť celý komentárin the ISO Standard 11092, and results were evaluated by the identical procedure mentioned there. The measurements were carried out at laboratory temperature 20-22oC, and the laboratory water vapour concentration (humidity) of the parallel airflow 45 - 60% was applied. The samples with dimensions 12x12cm were used.

The filtration effectivity was measured precisely on instrument MFP 1000 HEPA according to the requirements of the standard EN 149+A1 for respiratory protective devices, filtering half masks to protect again...Zobraziť celý komentárst particles or aerosol. Di-ethyl-hexyl-sebacat (DEHS) liquid suitable for producing steady aerosols was used as testing particles with the particles size 120 – 2000 nm. Testing area was 100cm2, face velocity was 5.3 cm/s, volume flow 32.0l/min. To obtain statistics value at least three samples were measured. Efficacy is obtained from an analysis of the number and size of particles passed through the test membrane

Did you test also filtration efficiency of smaller particles than 120 nm?

We are limited by the range of generator of aerosols, and the generator in the used device can generate the particles in the range 100 nm - 2500 nm (as I remeber well). The filtration efficiecy for 100nm par...Zobraziť celý komentárticles was 97.3%

I really like your work Alenka. Is there any effect of molar mass of PET on filtrattion efficiency or this does not play role at all? As far as I know during the recyclation of PET there is always decrease i...Zobraziť celý komentárn MM.

Evi, sorry, I did not completely answer your question. All the bottles what I tried had similar molar masses, so I am not able to evaluate the effect of MM on the filtration effectivity. However, generally, ...Zobraziť celý komentárthe MM of polymers effect the electrospinning condition but I do not see any mentions in literature that the MM effected the filtration. I would say that MM do not play a role in filtration. The important role play the diameters of the created fibers. We can talk about such a trend that the finer fibers (smaller diameters) the higher efficiency.

Thank you for comments. I measured the GPC of bottle-PET and PET after electrospinning and the results were similar, I do not want to say that almost identical. Mw = 44 300, Mn = 31 430 g/mol and PDI = 1.41 ...Zobraziť celý komentárfor bottle-PET and Mw = 43 800g/mol, Mn = 30 900 g/mol and PDI = 1,42 for Electrospun-PET. Electrospinning which is available in our laboratory use solutions for fibers formation and not melt, I would say, that MM of PET decrease because of the high temperature at conventional type of processing. And this is not our case.

Alenka, did you characterize porosity of nanofibre mats?

Juraj,
no I do not characterize the porosity of mats. I do not have contact with the technique or method. If you know somebody, who can help me with porosity I would be greatful