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Titre : Chemical properties of polymers Type de document : texte imprimé Auteurs : Tipanna Melkeri, Auteur Année de publication : 2021 Article en page(s) : p. 98-100 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Polymères -- Propriétés chimiques Index. décimale : 668.9 Polymères Résumé : Chemical resistance is the ability of a polymeric material to maintain its original properties such as mechanical, electrical, optical etc. when exposed to certain chemicals. The chemical structure of the polymer and functional group present in it is responsible for chemical resistance. Polymers are used in plastics as well as paints. Chemical resistance testing on plastic automotive materials is essential to gauge how such parts withstand the influence of mostly aggressive, automotive fluids such as fuels, biofuels, cleaners, cooling liquids and lubricants, often in combination with high temperature fluctuations. Steel structure has to be protected from the corrosion atmosphere specially in chemical industry so these structures are painted. The polymer used in these paints are must be resistance towards acid, alkali, solvents and other reactive chemical reagent. It is important that these polymer must exhibits good chemical resistance. Polymer can be affected by two ways either the chemical reagent acts as a solvent or chemical reagent attacks the polymeric material. Factors affecting the chemical resistance of the polymer are time of exposure, temperature of exposure, concentration of reagent, stress present in polymer and other ingredients present in plastics or paint formulations. Note de contenu : - INTRODUCTION : The chemical reagent act as a solvent - Chemical reagent attacks the polymeric material
- FACTORS AFFECTING CHEMICAL RESISTANCE : I) Time of exposure in the presence of the indicated chemical reagent - II) Temperature of expose - III) Stresses in molded and external to which the application is subjected - IV) Concentration of the indicated chemical reagent - V) Presence of other ingredients
- Solvent resistance testing : Test procedure - Specimen size - Data
- Table 1 : Material, Hansen parameters and Hilderbrand solubility parameter
- Table 2 : Chemical resistance of plasticsEn ligne : https://drive.google.com/file/d/1Z_E7kfN2Jk8k72my223vaKHmHsHxkW1R/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35229
in PAINTINDIA > Vol. LXXI, N° 1 (01/2021) . - p. 98-100[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 22557 - Périodique Bibliothèque principale Documentaires Disponible
Titre : Cholesteric liquid crystal pigments Type de document : texte imprimé Auteurs : Yash Melkeri, Auteur ; Tipanna Melkeri, Auteur Année de publication : 2017 Article en page(s) : p. 55-58 Langues : Anglais (eng) Catégories : Iridescence L’iridescence (aussi connu sous le nom de goniochromisme) est la propriété de certaines surfaces qui semblent changer de couleur selon l'angle de vue ou d'illumination. Des exemples d'iridescence comprennent notamment : les bulles de savon, les ailes de certains papillons, certains coquillages et certains minéraux. L'iridescence est souvent créée par une coloration structurelle de microstructures qui interfèrent avec la lumière.
Matières plastiques
Opacité (optique)
Pigments
Polymères à cristaux liquides cholestériques
Procédés de fabrication
Revêtements poudre:Peinture poudre
Revêtements:Peinture
SiliconesLes silicones, ou polysiloxanes, sont des composés inorganiques formés d'une chaine silicium-oxygène (...-Si-O-Si-O-Si-O-...) sur laquelle des groupes se fixent, sur les atomes de silicium. Certains groupes organiques peuvent être utilisés pour relier entre elles plusieurs de ces chaines (...-Si-O-...). Le type le plus courant est le poly(diméthylsiloxane) linéaire ou PDMS. Le second groupe en importance de matériaux en silicone est celui des résines de silicone, formées par des oligosiloxanes ramifiés ou en forme de cage (wiki).Index. décimale : 667.2 Colorants et pigments Résumé : Effect pigments are specialty pigments, display a wide range of properties such as colour-travel, reflect or refract light, act as a mirror (metal flakes) and multiple colour effect called Iridescence. Liquid crystals (LCs) are molecules that enter a state of malter showing characteristics of both isotropic melt and the ordered crystal when heated above their melting point. In liquid crystal polymer pigments (LCP pigment), a cholesteric phase is fixed by crosslinking therefore they also called cholesteric liquid crystal (CLC) pigments. CLC based pigment have excellent blue shifting colour travel. Most CLC pigments are based on polysiloxane. CLC Pigments are easily dispersed and compatible with most binder systems including water, solvent, and powder vehicle systems. Currently Wacker is the only commercial producer of CLC pigment under brand of Helicone HC. CLC pigments are used in both water and solvent based Paints. They also used in plastics due to their heat stability and resistance towards shear force. Note de contenu : - Application in liquid paint
- Application in powder coatings paints
- Application in plastics
- FIGURES : 1. Structure of nematic LC phase - 2. Twisted nematic LC - 3. Opacity and liquid crystal phase - 4. Cholesteric liquid crystal structure - 5. Iridescence effect in CLC pigment - 6. Colour travelling in CLC pigments - 7. History of CLC pigments - 8. Four different coloured helicone HC pigments - 9. CLC pigment manufacturing processEn ligne : https://drive.google.com/file/d/1vh2IA0WTfm_-mTYJAyWhT-hOiK2KQ0Tg/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28978
in PAINTINDIA > Vol. LXVII, N° 6 (06/2017) . - p. 55-58[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 19145 - Périodique Bibliothèque principale Documentaires Disponible
Titre : Colour physics Type de document : texte imprimé Auteurs : Tipanna Melkeri, Auteur Année de publication : 2020 Article en page(s) : p. 80-92 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Colorimétrie
Couleur
Essais (technologie)
Matières plastiques -- Coloration
Mélange de couleurs
Physique
Revêtements -- Coloration:Peinture -- ColorationIndex. décimale : 667.9 Revêtements et enduits Résumé : The colour wheel or colour circle is the basic tool for combining colours and has 12 colours based on the RYB model. Three primary colours namely Red, yellow and blue (RYB). Secondary colours are obtained by mixing primary colours, Orange, green and violet. Six more colours are obtained by mixing primary and secondary colours. Hue distinguishes one colour from another and is described using common colour names such as green, blue, red, yellow. Value refers to the lightness or darkness of a colour. It defines a colour in terms of how close it is to white or black. Chroma is the attribute that expresses the purity of a colour. When any hue is missed with black you get shade. A tint is any hue which is missed with white. When hue is mixed with both white and black, one get tone. It is degree to which the colour resembles to its hue. Colours which reflects light with mixtures of similar wavelength, the colour obtained is bright. Additive colour, or "additive mixing", is a property of a colour model that predicts the appearance of colours made by coincident component lights. The combination of two of the common three additive primary colours in equal proportions produces an additive secondary colour- cyan, magenta or yellow. Additive colour theory often used in theatrical lighting for plays, concerts, circus shows, and night clubs. Subtracting colouring uses dyes, inks, pigments, or filters to absorb some wavelengths of light and not others. The colour that a surface displays comes from the parts of the visible spectrum that are not absorbed and therefore remain visible. Measurement of colour is known as colorimetry. Variety of instruments are used to find colour properties. To measure colour value the source of light and viewing angle is very important. Tristimulus system, a system for visually match ing a colour under standardized conditions against the three primary colours-red, green and blue. X, Y, and Z are called tristimulus values. These values specify not only colour but also visually perceived reflectance. Commission Internationale d'Éclairage (CIE) in 1931, the chromaticity diagram is obtained by plotting these tristimulus values. For the rapid visual determination of the colour of objects, a colour atlas such as the Munsell book of colour is often used. The CIELAB colour space (also known as CIE L*a*b*. The Hunter Lab color space, defined in 1948 by Richard S Hunter, is another colour space sometimes referred to as "Lab". For the object with opacity greater than 75%, The Kubelka — Munk equation defines the relationship between spectral reflectance (%R), absorption (K) and scattering (S). Shades are compared using above techniques in paints, plastics chips, textile fabric. If one or more types of a person's colour-sensing cones are missing or less responsive than normal to incoming light, that person can distinguish fewer colours and is said to be colour deficient Note de contenu : - Colour theory
- Law of colour mixing
- Secondary colours
- Additive colouring
- Subtractive colouring
- Colour measurement
- Light source : View field (viewing angle) - Tristimulus measurements chromaticity diagram
- Characteristics of chromaticity diagram
- Munsell system : CIELAB system - Hunter lab system - Transferring spectrophotometer data into tristimulus value
- Colour difference : Kubelka- Munk theory
- Data correction
- Comparison of shades
- Testing in plastics
- Testing in paint
- Colour deficiency : Tetrachromacy - Synesthesia - Afterimages - Colour constancy - Colour naming - AssociationsEn ligne : https://drive.google.com/file/d/1C_xtP8QdPaxazVh6vmp4de7MVH4Yoa3Z/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34670
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Code-barres Cote Support Localisation Section Disponibilité 22360 - Périodique Bibliothèque principale Documentaires Disponible Copper phthalocyanine alpha blue (15.0, 15.1 and 15.2) / Tipanna Melkeri in PAINTINDIA, Vol. LXVIII, N° 4 (04/2018)
Accompagne High performance pigments (HPP) / Tipanna Melkeri in PAINTINDIA, Vol. LXVIII, N° 3 (03/2018)
Titre : Copper phthalocyanine alpha blue (15.0, 15.1 and 15.2) : Copper phthalocyanine (CPC pigment : Part 3) Type de document : texte imprimé Auteurs : Tipanna Melkeri, Auteur Année de publication : 2018 Article en page(s) : p. 69-71 Langues : Anglais (eng) Catégories : Phtalocyanine de cuivre
Pigments organiquesIndex. décimale : 667.2 Colorants et pigments Résumé : Copper phthalocyanine pigment (CuPC) is one of the most stable pigments towards light, temperature and chemicals. It exists in different crystal modifications. Crystal modifications α, and β have gained considerable commercial importance in industry . Crystal modification "α" is called pigment blue 15.0. It is obtained by acid pasting of crude CuPC. Pigment blue 15.0 is only stable upto 170°C. It shows very poor solvent resistant and also limited temperature stability. PB15.1 is improved version of PB15.0 with higher thermal stability but poor solvent stability. High thermal stability is achieved by surface modification of PB15.0 with suitable additive. Because high thermal stability it is used in all types of plastics and rubbers. PB15.2 is improved version of 15.1 with high solvent and thermal stability. All grades of pigment alpha blue are manufactured by process called acid pasting. Pigment alpha blue is used in various applications such as plastics, rubbers, ceramics, cements, inks, paints and cosmetics. Due to its high thermal stability, it is used in high performance coatings and engineering plastics. Note de contenu : - Manufacturing process of pigment "a" blue
- Pigment properties of "a" blue pigment
- Applications of pigment "a" blue
- Fig. 1 : Crystal structure of pigment blue 15.0 (pigment "a" blue)
- Fig. 2 : Reaction steps to manufacture heat stabiliser additive for PB15.1
- Fig. 3 : Schematic diagram showing manufacturing process of pigment blue 15, 15.1 and 15.2
- Table 1 : Comparative pigment properties of PB 15.0, 15.1 and PB 15.2 (5 is excellent and 1 is poor)
- Table 2 : Comparative pigment properties of PB 15.0, 15.1 and PB 15.2
- Table 3 : Various applications of PB 15.0, 15.1 and PB 15.2 and their suitabilityEn ligne : https://drive.google.com/file/d/175UnwNXTiFfQ9Ylaf45i09vVaV4fIHDj/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=30700
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Titre : Density and molecular weight of polymers Type de document : texte imprimé Auteurs : Tipanna Melkeri, Auteur Année de publication : 2020 Article en page(s) : p. 69-74 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Densité
Poids moléculaires
PolymèresIndex. décimale : 668.9 Polymères Résumé : Polymers are high molecular weight compound with low specific gravity (density) and high specific strength. Density of polymers are very low as compared to metal, however, the strength of these materials is relatively very high. Because of high strength to weight ratio polymers have replaced metals for many applications. The variation of density is because of the elements present in the polymer chain and structure of the polymer chain and arrangement of polymer chain. In Polyethylene, the arrangement of polymer chains can be vary, these are available in various densities. Polyethylene with high density have an ordered structure hence are more crystalline in nature with higher strength. Polymers contain polymer chains of unequal length, and so the molecular weight is not a single value - the polymer exists as a distribution of chain lengths and molecular weights. Different average values can be defined, depending on the statistical method applied. i) Number average molar mass or M, (also loosely referred to as Number Average Molecular Weight. ii) Mass average molar mass or M„, (also commonly referred to as Weight Average Molecular Weight iii) Z average molar mass or M, (z is for centrifugation; from German zentrifuge) and iv) Viscosity average molar mass or M. The number average molecular mass of a polymer can be determined by gel permeation chromatography, viscometry via the (Mark-Houwink equation), colligative methods such as vapor pressure osmometry, end-group determination or proton NMR. The mass average molecular mass can be determined by static light scattering, small angle neutron scattering, X-ray scattering, and sedimentation velocity. The graph of variation of number of polymer chains Ni vs molecular weight, is called molecular weight distribution curve. The polydispersity index is used as a measure of the broadness of a molecular weight distribution of a polymer. The ratio of the mass average to the number average is called the dispersity or the polydispersity index. MWD curve is narrow or wide depending upon the poly dispersity index. A narrow MWD is having better mechanical properties over wide MWD. Whereas the processability of the material is easy in wide MWD. Step polymerization reactions typically yield values of Mw/Mn of around 2.0, whereas chain reactions yield Mw/Mn values between 1.5 and 20. Molecular weight, Molecular weight distribution of the polymer is determined by various methods viz osmometry, end group analysis, light scattering method, sedimentation method, Gel permeable chromatography, Matrix-assisted laser desorption/ionization mass spectroscopy (MALDI-MS) and Diffusion-ordered NMR spectroscopy (DOSY). Note de contenu : - Density
- Determination of density of polymers
- Molecular weight distribution (MWD)
- Definitions of molar masses (molecular weight) : Number average molecular mass Mn - Weight average molecular weight : Mw - Z average molar mass, M" - Viscosity average molar mass, Mv - Molecular mass distribution curve
- Methods of molecular weight determination : Osmometry method - End group analysis method - Light scattering method - Sedimentation method
- Gel permeation chromatography (GPC)
- Matrix-assisted laser desorption/ionization mas spectroscopy (MALDI-MS)
- Diffusion-ordered NMR spectroscopy (DOSY)
- Table : Densities of some important polymersEn ligne : https://drive.google.com/file/d/1MUGifUS8EjGox1vy7THmlunq0778nrmZ/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34688
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