David Lukas, PhD

Chair of the Department of Nonwovens
Faculty of Textile Engineering, Technical University of Liberec

Chair of the Department of Nonwovens
Faculty of Textile Engineering, Technical University of Liberec, Liberec, Czech Republic, 2003 –
current.

Activities/Duties: Chair of the department with eight faculty members, four staff members, seven PH.D students, and fifty master's students.

Research:

• Application of ultrasound for an enhancement on nonwoven technology
  
• Electrospinning.
  
• Computer simulation of wetting phenomena in fibrous mass using Auto-models.
  
• Mechanical properties and behavior of nonwovens and fiber lattices
  
• Stereology of fibrous materials.
  
• Computer simulation of mechanical properties of fibrous nets.

Rector (President/Chancellor)
Technical University of Liberec, Liberec, Czech Republic, 1997 – 2002.
Activities/Duties: Top manager of the university, elective post for maximal twice three years.

Prorector (Vice-Rector)
Technical University of Liberec, Liberec, Czech Republic, 1996-1997.
Activities/Duties: University building property development.

Mass Production of Nanofibers Using Altering Current Electrospinning

Abstract: We show that AC electrospinning combined with an appropriately shaped needleless spinning electrode is highly efficient at generating a dense nanofibrous plume of nanofibers. The efficiency of this method is warranted by the virtual counter-electrode composed from oppositely-charged nanofibers. This virtual counter-electrode made by a cloud of nanofibers is regenerated periodically in each half-wave of the AC cycle.

The recombined pieces of freshly formed nanofibers are then moved by an electric wind to create the nanofibrous plume. The AC needleless electrospinning method introduced in [1] has the potential to be linked to existing technologies since it has a character of a gargoyle of nanofibres, which has no technological obstacle, e.g., collector, along the spinning line.

A promising application for nanofibrous plume is in the production of nanofibrous yarns. With the precipitous development in nano-science and nanotechnology, yarns composed of nanofibers may reveal entirely new opportunities for the development of nanofibrous structures such as woven and knitted fabrics, macrame and laces.

Thursday 2:00pm - 5:00pm
Concurrent Session II: Technology & Materials II

Technology for Production of Meltblown Microfiber Layers with High Amount of Nanofibers Produced by Electrospinning Process

Abstract: 1) The properties of layers containing nanofibers is very well known and their combination is in recent years applied. The problem of this combination consists in dramatic decreasing of productivity with decreasing fiber diameter. The meltblown technology is able produced fibers with diameter under 1 _m, typically about 800 nm. By this technique is possible to produce nanofibrous layers in industrial scale. Disadvantage of this technology is relatively low variety of meltable polymers. The main conditions are very low melt flow index, which is ensured by a lower molecular weight and suitable rheological properties of polymer.
2) The studies have shown that for a significant improvement of properties the layers can contains less than 10 % of nanofibers. This can be explained by very high specific surface. Also pores can be filled with thin nanofibers what is lead to lower pore size, but porosity is practically same. It leads to very high breathability.
3) The presentation is focused on possibilities of fiber layer production, which combines microfibers with nanofibers in smaller scale, but with higher mutual ratio of micro and nanofibers. A technical solution of this device will be shown. The device is based on electrospinning process and it can increase a ratio of nanofibers in a production of materials containing micro and nanofibers. The said needless electrospinning uses only one electrode. Productivity of this device is more than ten times higher compare to a roller spinning. Another advantage consists in a possibility to form the nanofibers by air flow. A produced layer can create for example parallely oriented fibers or bulky structures.