Małgorzata Gil

Physical sorption and thermogravimetry as the methods used to analyze linear polymeric structure

An increased interest in polymer optical fibers can be observed in the last years. One of the main problems in the technology of these fibers is achieving good optical and thermal stability of used polymer materials. This paper presents a series of manufactured poly(methyl methacryalte) samples which quality was investigated using the physical sorption and the thermogravimetry methods. Studies were carried out to optimize the composition of the starting mixtures used to obtain proper polymer optical fibers.

Copolymerization and thermal study of the new methacrylate derivative of 2,4,6-trichlorophenol

In this study, 2,4,6-trichlorophenyl methacrylate (TClPhMA) was synthesized by the reaction of methacryloyl chloride with 2,4,6-trichlorophenol in the ice bath condition. The obtained monomer was extracted by chloroform and purified on a chromatography column. In order to confirm the chemical structure of the new compound, spectroscopic studies (ATR-FTIR, 1H NMR, 13C NMR and GC–MS) were undertaken. The obtained TClPhMA was copolymerized with commercially available monomers such as methyl methacrylate, styrene, 1,4-divinylbenzene and 2-hydroxymethyl methacrylate. The copolymers were obtained by bulk polymerization in which benzoyl peroxide was used as a free radical initiator. The thermal properties of the copolymers were investigated by differential scanning calorimetry and thermogravimetry.

Low loss poly(methyl methacrylate) useful in polymer optical fibres technology

The paper presents the way that colour can serve solving the problem of calibration points indexing in a camera geometrical calibration process. We propose a technique in which indexes of calibration points in a black-and-white chessboard are represented as sets of colour regions in the neighbourhood of calibration points. We provide some general rules for designing a colour calibration chessboard and provide a method of calibration image analysis. We show that this approach leads to obtaining better results than in the case of widely used methods employing information about already indexed points to compute indexes. We also report constraints concerning the technique. Nowadays we are witnessing an increasing need for camera geometrical calibration systems. They are vital for such applications as 3D modelling, 3D reconstruction, assembly control systems, etc. Wherever possible, calibration objects placed in the scene are used in a camera geometrical calibration process. This approach significantly increases accuracy of calibration results and makes the calibration data extraction process easier and universal. There are many geometrical camera calibration techniques for a known calibration scene [1]. A great number of them use as an input calibration points which are localised and indexed in the scene. In this paper we propose the technique of calibration points indexing which uses a colour chessboard. The presented technique was developed by solving problems we encountered during experiments with our earlier methods of camera calibration scene analysis [2]-[3]. In particular, the proposed technique increases the number of indexed points points in case of local lack of calibration points detection. At the beginning of the paper we present a way of designing a chessboard pattern. Then we describe a calibration point indexing method, and finally we show experimental results. A black-and-white chessboard is widely used in order to obtain sub-pixel accuracy of calibration points localisation [1]. Calibration points are defined as corners of chessboard squares. Assuming the availability of rough localisation of these points, the points can be indexed. Noting that differences in distances between neighbouring points in calibration scene images differ slightly, one of the local searching methods can be employed (e.g. [2]). Methods of this type search for a calibration point to be indexed, using a window of a certain size. The position of the window is determined by a vector representing the distance between two previously indexed points in the same row or column. However, experiments show that this approach has its disadvantages, as described below. * E-mail: A.Nowakowski@ire.pw.edu.pl Firstly, there is a danger of omitting some points during indexing in case of local lack of calibration points detection in a neighbourhood (e.g. caused by the presence of non-homogeneous light in the calibration scene). A particularly unfavourable situation is when the local lack of detection effects in the appearance of separated regions of detected calibration points. It is worth saying that such situations are likely to happen for calibration points situated near image borders. Such points are very important for the analysis of optical nonlinearities, and a lack of them can significantly influence the accuracy of distortion modelling. Secondly, such methods may give wrong results in the case of optical distortion with strong nonlinearities when getting information about the neighbouring index is not an easy task. Beside this, the methods are very sensitive to a single false localisation of a calibration point. Such a single false localisation can even result in false indexing of a big set of calibration points. To avoid the above-mentioned problems, we propose using a black-and-white chessboard which contains the coded index of a calibration point in the form of colour squares situated in the nearest neighbourhood of each point. The index of a certain calibration point is determined by colours of four nearest neighbouring squares (Fig.1). An order of squares in such foursome is important. Because the size of a colour square is determined only by the possibility of correct colour detection, the size of a colour square can be smaller than the size of a black or white square. The larger size of a black or white square is determined by the requirements of the exact localisation step which follows the indexing of calibration points [3]. In this step, edge information is extracted from a blackand-white chessboard. This edge information needs larger Artur Nowakowski, Wladyslaw Skarbek Institute of Radioelectronics, Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warszawa, A.Nowakowski@ire.pw.edu.pl Received February 10, 2009; accepted March 27, 2009; published March 31, 2009 http://www.photonics.pl/PLP

Studies on the synthesis and physico-chemical properties of the new polymeric ion exchangers with sulphur groups

In this paper, new styrene microspheres with pendant methylenethiol or sulphonic groups are presented. The copolymer was obtained by the emulsion–suspension polymerization of aromatic tetrafunctional monomer 1,1′-bis[4-(2-hydroxy-3-acryloiloxypropoxy)phenyl] cyclohexane (C.DA) with styrene. This process was performed at constant mole ratio of C.DA to styrene (1:1 w/w). In order to introduce sulphur groups on the surface of the microspheres, the multistage modification was carried out. After modification very attractive methylenethiol (–CH2SH) and sulphonic (–SO3H) groups were introduced into the structure of microspheres. Elemental analysis and the spectroscopic method (attenuated total reflectance-Fourier transform infrared spectroscopy) were used to confirm the modification reaction. Thermal stabilities and degradation behaviours of the obtained copolymers were characterized by using thermogravimetry/differential scanning calorimetry/quadrupole mass spectrometry analyses.

Synthesis and characterization of new hybrid microspheres with amide functionalization

In this article, synthesis and characterization of new crosslinked hybrid microspheres are presented. This material was obtained by the emulsion-suspension polymerization of 1,4-divinylbenzene and trimethoxyvinylsilane. In the case of introducing biologically active functional groups on the surface of microspheres, methacrylamide as a third monomer was added. Chemical structures of all new materials were confirmed by the spectroscopic method (attenuated total reflectance-Fourier transform infrared spectroscopy) and elemental analysis. The influence of comonomer structure on the physico-chemical properties of the hybrid microspheres was investigated. Porous structures in a dry state were studied by means of nitrogen adsorption–desorption measurements. Thermal stabilities and degradation behavior of the obtained copolymers were characterized by the use of thermogravimetric/derivative thermo-gravimetric analysis.

Thermal and optical study of the new methacrylic copolymers useful in POF technology

This study the copolymerization and physico-chemical properties of the new copolymers of meth/acrylic esters: butyl acrylate (AB), ethylhexyl acrylate (AEH), or methyl methacrylate (MMA) with 2,2,2-trifluoroethyl methacrylate (TFEMA) used as a dopant are presented. Chemical structures of the copolymers were confirmed by attenuated total reflection–Fourier transform infrared (ATR/FT-IR) spectroscopy. Thermal properties of the synthesized materials were investigated by means DSC (Differential Scanning Calorimetry) and TG/DTG analyses. The influence of fluorinated dopant on the thermal and optical properties of the copolymers were evaluated in detail.

Study of physico-chemical properties of the new potential optical polymers based on 2-hydroxyethyl methacrylate

In this work synthesis, optymalization and study of physico-chemical properties of the new functionalized copolymers are presented. 2-Hydroxyethyl methacrylate (HEMA) and 2,4-dichlorophenyl methacrylate (2,4ClPh-M) copolymers have been prepared by bulk polymerisation. As a polymerization initiator (α,α’-azoiso-bis-butyronitrile) was used. A different weight ratio of HEMA to 2,4ClPh-M was applied. In this way 10 different copolymers were obtained. The structure of new materials was confirmed by spectroscopic methods (ATR-FTIR). The thermal stability of the obtained copolymers were studied by thermogravimetric analysis (TG/DTG).

Polymer-based composite active fiber doped with Tm 3+ and Yb 3+ — Technology and luminescent properties in VIS spectral range

Recent years observed significant development of the technology of luminescent materials for application in light sources (both coherent and incoherent) operating in the visible part of the spectrum. Undoubtedly, the most spectacular results have been obtained in the field of wide bandgap semiconductor lasers, considerable progress has been also observed in solid state lasers based on crystalline or glassy hosts with frequency conversion. Despite this results, however, there is still a room for development of entirely new types of active media, like e.g. composite polymers doped with optically active nanocrystals. Such a materials may potentially benefit from excellent luminescent properties of RE3+ doped nanocrystals and good optical and thermo-mechanical properties of polymer matrices enabling drawing the optical fibers based on these composites. In such a design nanocrystalline environment provides the protection of active ions from interactions with highly energetic phonons of polymer matrix and simultaneously, polymer host encapsulating nanoparticles shields these from interactions with OH− groups and other contaminations.

High birefringent microstructured polymer optical fiber with frozen stresses

We report on fabrication of a new type high birefringent microstructured polymer fiber with a PMMA stress applied element in the core. An inner part of preform consists regular three rings of holes, made by drilling method. Inside the microstructure we drilled an additional hole, where a special type – strongly stressed PMMA rod was placed. The manufactured preform was measured in an polarimetric microscope configuration where we observed very large internal stresses - especially seen in a core area.

Spectral characteristics of PMMA doped with dimethacrylate derivative of naphthalene-2,7-diol use full in UV sensors

The paper presents the way that colour can serve solving the problem of calibration points indexing in a camera geometrical calibration process. We propose a technique in which indexes of calibration points in a black-and-white chessboard are represented as sets of colour regions in the neighbourhood of calibration points. We provide some general rules for designing a colour calibration chessboard and provide a method of calibration image analysis. We show that this approach leads to obtaining better results than in the case of widely used methods employing information about already indexed points to compute indexes. We also report constraints concerning the technique. Nowadays we are witnessing an increasing need for camera geometrical calibration systems. They are vital for such applications as 3D modelling, 3D reconstruction, assembly control systems, etc. Wherever possible, calibration objects placed in the scene are used in a camera geometrical calibration process. This approach significantly increases accuracy of calibration results and makes the calibration data extraction process easier and universal. There are many geometrical camera calibration techniques for a known calibration scene [1]. A great number of them use as an input calibration points which are localised and indexed in the scene. In this paper we propose the technique of calibration points indexing which uses a colour chessboard. The presented technique was developed by solving problems we encountered during experiments with our earlier methods of camera calibration scene analysis [2]-[3]. In particular, the proposed technique increases the number of indexed points points in case of local lack of calibration points detection. At the beginning of the paper we present a way of designing a chessboard pattern. Then we describe a calibration point indexing method, and finally we show experimental results. A black-and-white chessboard is widely used in order to obtain sub-pixel accuracy of calibration points localisation [1]. Calibration points are defined as corners of chessboard squares. Assuming the availability of rough localisation of these points, the points can be indexed. Noting that differences in distances between neighbouring points in calibration scene images differ slightly, one of the local searching methods can be employed (e.g. [2]). Methods of this type search for a calibration point to be indexed, using a window of a certain size. The position of the window is determined by a vector representing the distance between two previously indexed points in the same row or column. However, experiments show that this approach has its disadvantages, as described below. * E-mail: A.Nowakowski@ire.pw.edu.pl Firstly, there is a danger of omitting some points during indexing in case of local lack of calibration points detection in a neighbourhood (e.g. caused by the presence of non-homogeneous light in the calibration scene). A particularly unfavourable situation is when the local lack of detection effects in the appearance of separated regions of detected calibration points. It is worth saying that such situations are likely to happen for calibration points situated near image borders. Such points are very important for the analysis of optical nonlinearities, and a lack of them can significantly influence the accuracy of distortion modelling. Secondly, such methods may give wrong results in the case of optical distortion with strong nonlinearities when getting information about the neighbouring index is not an easy task. Beside this, the methods are very sensitive to a single false localisation of a calibration point. Such a single false localisation can even result in false indexing of a big set of calibration points. To avoid the above-mentioned problems, we propose using a black-and-white chessboard which contains the coded index of a calibration point in the form of colour squares situated in the nearest neighbourhood of each point. The index of a certain calibration point is determined by colours of four nearest neighbouring squares (Fig.1). An order of squares in such foursome is important. Because the size of a colour square is determined only by the possibility of correct colour detection, the size of a colour square can be smaller than the size of a black or white square. The larger size of a black or white square is determined by the requirements of the exact localisation step which follows the indexing of calibration points [3]. In this step, edge information is extracted from a blackand-white chessboard. This edge information needs larger Artur Nowakowski, Wladyslaw Skarbek Institute of Radioelectronics, Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warszawa, A.Nowakowski@ire.pw.edu.pl Received February 10, 2009; accepted March 27, 2009; published March 31, 2009 http://www.photonics.pl/PLP