Liana Sharashidze

We have developed a novel UV radiation dosimeter that allows a real-time estimation of the dose of harmful ultraviolet UV-A, UV-B, and UV-C radiations emitted by the sun and artificial sources. When exposed to UV radiation, our UV Dosimeter visibly change color from the starting light-yellow to blue to dark violet. The color change correlates to levels of accumulated UV irradiation. The proposed UV dosimeter enables users to control a skin sunburn level caused by UV light from the sun and artificial sources, and visually monitor how much harmful radiation has been delivered to a surface, which helps them see if surfaces have received enough energy to kill bacteria, viruses, and spores – including Covid-19. The proposed UV dosimeter is environmentally safe, exhibits excellent photochromic properties, improved photosensitivity, high spatial resolution. It can be efficiently reused over 200 cycles without compromising its readability.

One of the actual directions of modern polymer science is creation and research of graded materials with different (mechanical, optical, electrical, magnetic, etc.) properties. There are different methods of receiving such materials. We have developed and patented the original technical solution for obtaining graded polymer and composite materials, according to which the creation of gradient of properties is conditioned by graded orientation of isotropic materials. Graded orientation is created using specific devices. The improvement of the technical characteristics of these devices significantly contributes to the development of graded material science. The constriction of the addon device is proposed that allows to carry out of graded orientation in combination of addon device with any standard stretching machine. A mathematical model of graded orientation of polymer materials is developed, which enables to work out polymer materials with preset dimensions and distribution of relative elongation.

The simplest and most common kind of orientation of polymers is the uniaxial orientation - action of a uniform mechanical field on the polymer sample. Uniaxial oriented stretching can be carried out in another mode. Scientific basis of this innovations is a concept about newstructural state of the thermo-plastic polymers – about gradually oriented state (GOS) proposed by us for the first time. This state quan-titatively is described by three parameters:range of the relative elongation change, its extent and distri-bution profile (linear, hyperbolic, parabolic, logarithmic, sinusoidal, etc). On the basis of this conce-ption a fundamentally technical solution of the uniaxial orientedstretching is developed. This is the orientation of thermoplastic polymers in the gradient mode, which is done by action of the inhomogeneous mechanical field on the izotropic polymer films. There are elaborated some guided graded orientation methods.  

A major focus of polymer science twenty-first century is to obtain materials and elements with a gradient of different properties. The gradient of the properties in the polymer body may be formed by the gradient of chemical composition, as well using a gradient orientation of polymers. The idea of the degree of gradient orientation, as a new characterization of polymer material – new structural state (gradient-oriented state) in science was first introduced by us. According to this view, the transition of the polymer in a gradient oriented state makes it possible to obtain polymer materials of new generation, with a gradient of mechanical, thermal, optical, electrical, magnetic, acoustic and other properties. Obtaining materials with desired properties stimulate the emergence of new scientific directions. Gradient-oriented state is created under the influence of inhomogeneous mechanical field on the polymer body. In the present study investigated to obtain rectangular pieces with a hyperbolic distribution of relative elongations perpendicular to the single axle stretching of the polymer film. Essence of the method described below.  

A method has been developed for producing rectangular polymeric films, in which the distribution function of directional relative tensions in the direction of orientation is a hyperbola. If the shape of the original sample is a curvilinear trapezoid and the distribution function is planned in advance, then a system of equations is adopted to determine the dimensions of the sample. The method makes it possible to obtain polymer films with a given gradient of all properties depending on the degree of orientation.

Introduction in science of a new specific state of polymer materials and corresponding new physical characteristic – notion of gradientally oriented state essentially widens view on the generally polymer science problems. The results obtained in this sphere will principally increase the possibilities of regulation of mechanical, thermal, electric, optical, acoustic and other properties of polymers, they will give an impulse to formation of a new scientific directions, as it had already happened on the example of GB-optics. The method of formation of optical polymer elements, having gradient of birefringence (GB-elements) and experimental results of its polarizable properties study are described.GBelements was made using thin films of PVA (PVA,d=100-150 mk) and Polyethylentherephtalate (PETPh,d=190mk). A polymer film to be stretched is placed between clamps. The inter-location and/or their form has been selected so, that it is provided with preliminary established gradient of relative lengthens in various sections of polymer sample. By means of variation of other parameters (value, rate and distribution of deformation, temperature, environment, the chemical structure of polymer) it is possible to regulate gradient oriented state of polymers. Characterization of this state will be effected by means of observation on polarized light through the polarized microscope and studying of birefringence. Thus, the birefringence is a testing characteristic of gradient oriented state and at the same time it may be itself a purposeful property of the material. It is shown, that in the middle of GB-element gradient of birefringence Δn increases exponentially across the central axes z, and = 0,02 .Increasing of GB-element formation temperature from 80 Δn 0 to 900 C improve linearity of the relation Δn = f(z), but in the peripheric zone line is broken.  

Fabrication a new type of polymeric optical elements with specified properties- with the given axial gradient birefrigence(GB) is described. For fabrication GB-elements the inhomologeneous mechanical field with the given heterogeneity is used. The GB- elements onPVS and PETPh thin filmsbasesare created and their properties are investigated.

Doctoral Thesis Referee

Master Theses Supervisor

Doctoral Thesis Supervisor/Co-supervisor

Scientific editor of monographs in foreign languages

Scientific editor of a monograph in Georgian

Editor-in-Chief of a peer-reviewed or professional journal / proceedings

Review of a scientific professional journal / proceedings

Member of the editorial board of a peer-reviewed scientific or professional journal / proceedings

Participation in a project / grant funded by an international organization

Participation in a project / grant funded from the state budget

Patent authorship

Membership of the Georgian National Academy of Science or Georgian Academy of Agricultural Sciences

Membership of an international professional organization

Membership of the Conference Organizing / Program Committee

National Award / Sectoral Award, Order, Medal, etc.

Honorary title

Monograph

Handbook

Research articles in high impact factor and local Scientific Journals

Publication in Scientific Conference Proceedings Indexed in Web of Science and Scopus