I am using hemp fibers to make a CNF solution; how much should be the concentration to vacuum filter and get a transparent nanopaper?
Vadym Chibrikov thankyou for your response. Could you explain why mass is 100-150mg?
Good day! That is my fault, as far I have mixed some values for different cellulose materials, thus, I apologize on that. Thickness of more or less handful and applicable CNF film should be 60 um in general, which is in touch with data in literature. However, to reach it, thickness of wet-state layer should be lower than I mentioned before (I suppose 1 mm max in that case), as well as porosity should be included as 15-20%. Suppose, you have the same filter with 5 cm diameter. Then, according to equation of cylinder volume, V=pi*r^2*h = 3.14*2.5^2*0.1 = 2 cm3. Including film porosity, volume is 1.6 cm3. As far, cellulose density is 1.45 g/cm3, cellulose mass should be 2.3 g. In literature, they are starting in different ranges from 1 to 10% wt., so, probably, should you.
Vadym Chibrikov Thankyou again for your response.
why do you think the porosity is 15-20% and which way can I find that out?
Also, is 2.3g based on the 5cm filter membrane (per se) the smallest amount of cellulose I need to deposit a thin film? that would be transparent?
Rajeswari Sen Good day!
1. Why porosity is 15-20%? Porosity of up to 15-20% is a maximum value for tailor-made cellulose-based membranes, that is shown in literature. It depends on type of membrane, material sources, ways of its production and modification, however, trends are like this.
2. Methods on porosity measurement. Usually, researches of membranes use capilary flow porometry, or mercury porometry.
3-4. Smallest amount of CNF and film transparency. Of course, you may try to produce thinner films. However, according to my expertise on cellulose-based materials, and recently provided calculations, 60 um would be an optimum value, that will allow you to use low amount of material, and produce both handful and transparent films.
Additionally to all info that I have provided, I recommend you to find some extra info in papers, dedicated to production of cellulose-based materials for food biopackaging. In such kind of articles, authors generally consider materials to have oxygen/nitrogen/gas permeability, be transparent and provide some kind of mechanical properties, that are necessary for packaging materials (oppose stretching, multiple bendings etc.).
If you have found current answer as useful, please, do not forget to reccommend it. That will help other researches to find the best answer, according to their purposes. Best of luck in your research!
What is the diameter of the nanopaper that you want to produce? What will your end purpose be? How do you plan on retaining the CNC fibers? Sorry for all of the questions, but would be helpful to understand what your goal is in producing the hemp nano-paper. If you simply want to produce a transparent film for testing purposes. Here is a good article to read. CNC by themselves tend to be somewhat brittle, so producing a composite film is a good method for assessing their strength.
"Mechanical enhancement of cellulose nanofibril (CNF) films through the addition of water-soluble polymers". E.S. Forti, Cellulose (2021)
https://doi.org/10.1007/s10570-021-03937-0
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