1. The Study of Structural porosity of melt blown Lyocell fibres
Dr. Umer Farooq
University of Management and Technology, Lahore

2. Presentation Layout Introduction Aims and Objectives of the Research
The Experimental
Results and Discussion
Conclusions
Future Research

3. Lyocell Fibres Melt Blowing Process
Introduction
Lyocell Fibres
Melt Blowing Process

4. Lyocell Fibres Latest addition to Regenerated Cellulosic Fibres
Overcome the disadvantages associated with conventional regenerated cellulosic fibres
Environmental Pollution
Hazardous By-products
High cost to production ratio

5. The Lyocell Process Wood Pulp Solution Solvent Recovery Filtration
NMMO +WATER
Solution
NMMO +WATER
Solvent Recovery
Filtration
The Lyocell Process
Spinning
Spinning Bath
Washing
and
Drying
Distillate Water
FIBRES

6. Melt Blowing
“… one step process in which high velocity fluid – normally air – blows molten thermoplastic resin from an extruder die tip on to a conveyor, take-up screen or substrate to form a fine fibered self bonded web”

7. Schematic of MB process

8. Air flow through the die assembly

9. The Melt Blowing Rig

11. Objectives of the Research
To investigate the possibility of producing melt blown lyocell fibres with increased absorbency for a given dope concentration by changing the coagulation conditions

12. Objectives …
To study the effect of changing the temperature of the coagulating bath on the porosity of the resultant melt blown lyocell fibres, when:
the fibres are still saturated with water, i.e. the fibres are not allowed to dry after the collection,
the fibres are dried at 110oC after collecting in the coagulating bath.
The fibres dried at room temperature after collecting in the coagulating bath.

13. Objectives …
To study the effect of changing the temperature of the coagulating bath containing high percentages of NMMO on the porosity of the resultant melt blown lyocell fibres.
To study the effect of changing the temperature of the coagulating bath on the resultant fibre diameter of the lyocell fibres and to investigate the dependance of the resultant porosity on the fibre diameter.
To study the structure of melt blown lyocell fibre webs, thus produced.

14. The Experimental Constant Parameters of the System:
Hot Air Temperature: 140oC +/- 5oC
Hot Air Flow Rate: litres / sec
Nitrogen Gas Pressure: 10 bars
Dope Temperature: 100oC + / - 5oC
Experimental Variables
The temperature of the coagulating bath - 2oC to 93oC
The concentration of NMMO in the coagulating bath - only a high concentration of NMMO with different bath temperatures was investigated.

15. Sample Collecting Methods
Wet Saturated (W.S) Samples Collected on the Drum
W.S. Samples Collected Directly in the Water Bath
Samples Dried at Room temperature
W.S. Samples Collected in Concentrated Solution of NMMO
Analytical Measurements
Water Imbibition (W.I)
Fibre Diameter using a projection microscope.

16. Water Imbibition
… measure water contained in the water accessible pores of a wet saturated fibre structure in relation to dry fibre mass.
According to a research, the voids in the lyocell fibres are entirely air filled in dry fibres and entirely water filled in water swollen fibres.
… a good approximation of the porosity of the fibre structure.

17. Results and Discussion

27. Discussions Phase inversion in Ternary System
Binodal line represents the boundary at which the concentration of each component which could result into liquid-liquid demixing in the system at the given temperature of the extrudate
Binodal Area

28. Instantaneous and delayed demixing

29. Rapid decrease in porosity of dried samples
Macro Void Hypothesis
The Fine Structure Hypothesis

30. Conclusions
The water imbibition of all the wet saturated samples seems to increase linearly with increase in the bath temperature. This could be attributed to higher rates of diffusion of water into the polymer solution extrudate and NMMO out of the extrudate at higher bath temperatures.

31. Conclusions …
The water imbibition of wet saturated samples collected in 63.4% NMMO in the bath was found to be less than the samples collected in the water bath. The diminishing concentration gradient of NMMO between the polymer solution extrudate and the coagulating bath and its effect on phase inversion system were accounted for this change.

32. Conclusions …
On drying the water imbibition of wet saturated samples at 110oC the water imbibition of the fibres not only declined remarkably but it was observed that samples having higher imbibition values when wet i.e. samples collected at higher bath temperatures, show the maximum drop in their water imbibition values.

33. Conclusions …
Fibre diameter varies greatly both within and between the fibres and seems to be independent of the bath temperature.
The structure of the melt blown fibre web under projection microscope (Magnification of 250) seems to be made up of continuous fibres, with a very small amount of branching.

34. Future Research
Investigation of the crystallinity of the melt blown fibres at various bath temperatures.
Study of the change in porosity with varying bath temperature at different fibre diameters.
Collection of fibres on a heated surface.
Thank you!