DETERMINATION OF BASIC CHARACTERISTICS OF PROTECTIVE LAYERS BASED ON POLYMERIC NANOFIBERS
This work focuses on a basic research in developing new class of protective layers for building materials based on polymeric nanofibers. Nonwoven nanotextiles are fibers with diameter spanned from tens to hundreds of nanometers. Thin films consisting of suitable polymer-based nanofibers were prepared using NANOSPIDER equipment. Applied technology is unable to fully guarantee quality (homogeneity, thickness, etc.) of the protective coating. Traditionally used technologies –such as painting or spraying – are not too effective and the separation of protective coating or loosing of protective properties is frequently observed.
Modeling Interior Environment of Historical Building and Determination of Critical Places for Application of Nanotextiles Protection
Reconstruction of internal plaster in historical buildings belongs to significant and obvious treatment in a landmark area that helps protect irreplaceable cultural resources. Original form of historical buildings has been usually altered over time and alterations are an important part of the building's history. These interventions don ́t often respect the basic function of interior. Results of these changes cause plaster and painting decay, slow air flow and higher air moisture concentration. Computer simulation plays major role in determining places where is necessary to apply surface protection that will preserve the valuable interior surface against negative influences such as high level of moisture, fungus, chemical reactions etc. Abatement of negative influences within historic buildings requires particular care if important historic finishes are not to be adversely affected. Reconstruction of historical interiors should be designed to minimize visual changes to a historic building. Choosing the most appropriate treatment for a historical building requires careful decision making about using of appropriate material for renovation. Using of nanofibers should be minimal modifications to the historic appearance and protect from negative influences.
Intensification of Bubble Disintegration and Dispersion by Mechanical Stirring in Gas Injection Refining
Water model experiments were performed for establishing highly efficient gas injection refining processes. Mechanical stirring was applied to disintegrate the injected bubbles and to disperse them widely in the bath. The bubble disintegration and dispersion were investigated by changing rotation mode (direction of rotation), rotation speed, blade size of the impeller and gas flow rate. Forward rotation of the impeller induced a stable tangential flow and could not disperse bubbles in the bath due to formation of a vortex around the impeller shaft. The tangential flow could be suppressed by forward–interrupt rotation, which could reduce the vortex formation to some degree. However, forward–interrupt rotation could not disperse the bubbles widely in the bath. Forward–reverse rotation could prevent the vortex formation completely and create a strong shear stress field, which intensified the bubble disintegration and dispersion in the bath. Higher impeller rotation speed and larger blade length in forward–reverse rotation could enhance the bubble disintegration and make the dispersed bubbles smaller. The bubble dispersion zone became wider with larger blade length. The bubble size tended to be larger at higher gas flow rates. However, its dependence on the gas flow rate became smaller at higher impeller rotation speed.