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Yellowness Index (yellowness + index)
Selected AbstractsFluorescence and coloration of grey hairINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2009S. Daly Synopsis Grey hair samples were collected from 11 individuals and separated into un-pigmented and pigmented fibres (International Hair Importers). Fluorescence measurements were obtained by using a double-grating fluorescence spectrophotometer and a bifurcated fibre optics accessory to measure the spectra directly from the surface of hair at various distances from the fibre root. Colour measurements were carried out by using a Hunter colorimeter. The fluorescence spectra of un-pigmented hair obtained by the excitation at 290 nm show a peak at 356 nm [tryptophan (Trp)], and multi-peak emissions in the range from 395 to 500 nm. A significant variation in the Trp emission intensity at 356 nm vs. the intensity of emission in the 395,500 nm range was observed for hair collected from various individuals with yellow coloured hair producing stronger relative emission in 395,500 nm range. Quantitative measurements of coloration and the calculation of the Yellowness Index (YI) showed linear correlation between YI and the ratio of fluorescence intensities I440/I356 The spectra obtained by excitation at 320 nm showed the emission peaks at 395 nm (unidentified), 420 nm (N -formylkynurenine), 460 nm (kynurenine), and 495 nm (3-hydroxykynurenine), which are the products of oxidative or metabolic conversion of tryptophan. Un-pigmented, yellow hair showed a build-up of the fluorescence band corresponding to 3-hydroxykynurenine at 495 nm. The data also showed the fluorescence quenching effect of melanin resulting in the lowering of the fluorescence intensity of pigmented hair. The spectra obtained at various positions along the fibres demonstrated gradual photo-decomposition of hair chromophores during their lifetimes. This was indicated by a decrease of Trp fluorescence intensity, which was relatively fast (8·10,4,1.5·10,3 [day,1] as calculated for hair obtained from various individuals) for un-pigmented hair and slower for pigmented hair. A decrease in Trp emission was accompanied by an increase in the yellow coloration toward the ends of un-pigmented fibres. Resume Des échantillons de cheveux gris ont été collectés chez onze personnes et triés entre fibres non pigmentés et fibres pigmentés (International Hair Importers). Les mesures de fluorescence ont été réalisées à l'aide d'un spectrophotomètre de fluorescence double grille et d'un accessoire constitué d'une fibre optique bifurquée. Ce dispositif permet la mesure du spectre directement depuis la surface d'un cheveu à diverses distances de sa racine. Les mesures de couleur ont été réalisées à l'aide d'un colorimètre HUNTER. Le spectre de fluorescence d'un cheveu non pigmenté obtenu par excitation à 290 nm montre un pic à 356 nm (tryptophane : Trp) et des émissions multi pics dans l'intervalle 395 à 500 nm. On observe une variation significative de l'intensité du Trp à 356 nm par rapport à l'intensité d'émission dans l'intervalle 395,500 nm sur les cheveux prélevés sur diverses personnes, les cheveux colorés en jaune produisant une émission relative plus forte dans l'intervalle 395,500 nm. Les mesures quantitatives de la couleur et le calcul de l'indice de jaunissement (YI) montrent une corrélation linéaire entre YI et le rapport des intensités de fluorescence I 440/I356. Le spectre obtenu par excitation à 320 nm montre des pics d'émission à 395 nm (non identifiés), 420 nm (N-formylkynurenine), 460 nm (kynurenine), 495 nm (3-hydroxy kinurenine) propres aux produits d'oxydation ou de conversion métabolique du Tryptophane. Les cheveux jaunes non pigmentés présentent une saturation de la bande de fluorescence correspondant à la 3-hydroxykynurenine à 495 nm. Ces données montrent également l'effet de quenching de la mélanine entraînant un affaiblissement de l'intensité de la fluorescence des cheveux pigmentés. Le spectre obtenu en divers endroits le long des fibres indique une photodécomposition graduelle des chromophores des cheveux durant leur temps de vie. Ceci se traduit par une diminution de l'intensité de fluorescence du Trp qui est relativement rapide pour les cheveux non pigmentés (8,10,4,1,5,10,3 [jour , 1], conformément aux calculs effectués sur des cheveux prélevés sur différents individus) et par une diminution plus lente pour les cheveux pigmentés. Une diminution de l'émission du Trp s'accompagne d'une augmentation de la coloration jaune de l'extrémité des cheveux, détectable sur des cheveux non pigmentés. [source] A novel route for preparation of PVC sheets with high UV irradiation resistanceJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Xianke Ye Abstract A novel acrylonitrile acrylate copolymer coating was proposed to improve the UV irradiation resistance of poly(vinyl chloride) (PVC) sheets. Its effect on the photoageing properties of the sheets was evaluated by means of Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), yellowness index test, and the oxygen permeability coefficient and mechanical properties measurement. The experimental results show that the novel acrylonitrile acrylate copolymer coating significantly improves the UV irradiation resistance of PVC sheets. Compared with the PVC sheets without coating, the coated PVC sheets show better mechanical properties, lower yellowness index, and smaller oxygen permeability coefficient after UV irradiation. The analysis on the SEM images of the PVC sheets indicates that the coating acts as a film to prevent the PVC sheets from UV energy and oxygen that can accelerate the photochemical reactions of PVC. The FTIR analysis confirms that the coating can slow down the microstructures development of the PVC sheets, also indicating that the coating impeded the photochemical reactions of PVC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] WATER ABSORPTION, LEACHING and COLOR CHANGES DURING the SOAKING FOR PRODUCTION of SOY-BULGURJOURNAL OF FOOD PROCESS ENGINEERING, Issue 2 2004MUSTAFA BAYRAM ABSTRACT In this study, the soaking process, which is the first step of soy-bulgur production to develop a new type food product, was investigated. the soaking operation was conducted at 30, 50 and 70C for 120 min and samples were taken from the soybean and soaking water at 10 min intervals. Moisture content and color (L, a, b and YI values) of soybean were measured, as well as soluble solids content and color (L, a, b and YI values) of soaking water during the soaking process. the results were analyzed by using ANOVA and Duncan test. Soaking time and temperature were significantly effective (P < 0.05) on all variables, except the time effect on the YI-value. During the soaking, moisture content, lightness (L) and yellowness (b) increased and, redness (a) and yellowness index (YI) of soybean decreased. Soluble solids content, yellowness and yellowness index increased in contrast to a decrease in the lightness and greenness of the soaking water. As a result, soluble solids content in the soaking water increased, which illustrated the leaching of soluble solids from soybean to water. Color of soybean turned to lights, in contrast to darkening and opaqueness of water during soaking. Results showed that the moisture content, soluble solid content, L, a, b and YI values can be successfully modeled using polynomial equations, which can be used to estimate their changes during the soaking operation. [source] Novel organosoluble and colorless poly(ether imide)s based on 3,3-bis[4-(3,4-dicarboxyphenoxy)phenyl]phthalide dianhydride and aromatic bis(ether amine)s bearing pendent trifluoromethyl groupsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2006Chin-Ping Yang Abstract A novel series of colorless and highly organosoluble poly(ether imide)s were prepared from 3,3-bis[4-(3,4-dicarboxyphenoxy)phenyl]phthalide dianhydride with various fluorinated aromatic bis(ether amine)s via a conventional two-stage process that included ring-opening polyaddition to form the poly(amic acid)s followed by cyclodehydration to produce the polymer films. The poly(ether imide)s showed excellent solubility, with most of them dissoluble at a concentration of 10 wt % in amide polar solvents, in ether-type solvents, and even in chlorinated solvents. Their films had a cutoff wavelength between 358 and 373 nm, and the yellowness index ranged from 3.1 to 9.5. The glass-transition temperatures of the poly(ether imide) series were recorded between 237 and 297 °C, the decomposition temperatures at 10% weight loss were all above 494 °C, and the residue was more than 54% at 800 °C in nitrogen. These films showed high tensile strength and also were characterized by higher solubility, lighter color, and lower dielectric constants and moisture absorption than an analogous nonfluorinated polyimide series. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3140,3152, 2006 [source] Synthesis and properties of fluorinated polyimides based on 1,4-bis(4-amino-2-trifluoromethylphenoxy)-2,5-di- tert -butylbenzene and various aromatic dianhydridesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2004Chin-Ping Yang Abstract A novel fluorinated diamine monomer, 1,4-bis(4-amino-2-trifluoromethylphenoxy)-2,5-di- tert -butylbenzene (2), was prepared through the nucleophilic substitution reaction of 2-chloro-5-nitrobenzotrifluoride and 2,5-di- tert -butylhydroquinone in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Fluorinated polyimides (5a,5f) were synthesized from diamine 2 and various aromatic dianhydrides (3a,3f) via thermal or chemical imidization. These polymers had inherent viscosities of 0.77,1.01 dL/g. The 5 series polyimides were soluble in N -methyl-2-pyrrolidone, N,N -dimethylacetamide, and N,N -dimethylformamide and were even soluble in dioxane, tetrahydrofuran, and dichloromethane. 5(C) showed cutoff wavelengths between 363 and 404 nm and yellowness index (b*) values of 6.5,40.2. The polyimide films had tensile strengths of 93,114 MPa, elongations to break of 9,12%, and initial moduli of 1.7,2.1 GPa. The glass-transition temperatures were 255,288 °C. The temperatures of 10% weight loss were all above 460 °C in air or nitrogen atmospheres. In comparison with a nonfluorinated polyimide series based on 1,4-bis(4-aminophenoxy)-2,5-di- tert -butylbenzene, the 5 series showed better solubility and lower color intensity, dielectric constants, and moisture absorption. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2272,2284, 2004 [source] Effects of diamines and their fluorinated groups on the color lightness and preparation of organosoluble aromatic polyimides from 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]-hexafluoropropaneJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2003Chin-Ping Yang Abstract To investigate the position and amount of the CF3 group affecting the coloration of polyimides (PIs), we prepared 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane (2) with four CF3 groups with 2-chloro-5-nitrobenzotrifluoride and 2,2-bis(4-hydroxyphenol)hexafluoropropane. A series of soluble and light-colored fluorinated PIs (5) were synthesized from 2 and various aromatic dianhydrides (3a,3f). 5a,5f had inherent viscosities ranging from 0.80 to 1.19 dL/g and were soluble in amide polar solvents and even in less polar solvents. The glass-transition temperatures of 5 were 221,265 °C, and the 10% weight-loss temperatures were above 493 °C. Their films had cutoff wavelengths between 343 and 390 nm, b* values (a yellowness index) ranging from 5 to 41, dielectric constants of 2.68,3.01 (1 MHz), and moisture absorptions of 0.03,0.29 wt %. In a comparison of the PI series 6,8 based on 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]propane, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane, we found that the CF3 group close to the imide group was more effective in lowering the color; this means that CF3 of 5, 7, and 8f was more effective than that of 6c. The color intensity of the four PI series was lowered in the following order: 5 > 7 > 6 > 8. The PI 5f, synthesized from diamine 2 and 4,4,-hexafluoroisopropylidenediphthalic anhydride, had six CF3 groups in a repeated segment, so it exhibited the lightest color among the four series. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 922,938, 2003 [source] Additive interactions in the stabilization of film grade high-density polyethylene.JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 2 2002Part I: Stabilization, influence of zinc stearate during melt processing The melt stabilization activity of some of the most commercially significant phenolic antioxidants and phosphites (alone and in combination), without and with zinc stearate, was studied in high-density polyethylene (HDPE) produced by Phillips catalyst technology. Multiple pass extrusion experiments were used to degrade the polymer melt progressively. The effect of stabilizers was assessed via melt flow rate (MFR) and yellowness index (YI) measurements conducted as a function of the number of passes. The level of the phenolic antioxidant remaining after each extrusion was determined by high-performance liquid chromatography (HPLC). Phenolic antioxidants and phosphites both improved the melt stability of the polymer in terms of elt viscosity retention; the influence of zinc stearate was found to be almost insignificant. However, phosphites and zinc stearate decreased the discoloration caused by the phenolic antioxidants. A correlation was found between the melt stabilization performance of phosphites and their hydroperoxide decomposition efficiency determind via a model hydroperoxide compound. Steric and electronic effects associated with the phosphorus atom influenced the reactivity towards hydroperoxides. Furthermore, high hydrolytic stability did not automatically result in lower efficiency. Besides phosphite molecular structure, stabilization activity was also influenced by the structure of the primary phenolic antioxidant and the presence of zinc stearate. [source] New Shade Guide for Evaluation of Tooth Whitening,Colorimetric StudyJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 5 2007RADE D. PARAVINA DDS ABSTRACT Statement of the Problem:, Available shade guides lack colorimetric uniformity, which compromises the validity of visual evaluation of tooth whitening efficacy. Purpose:, The objective of this study was to perform a colorimetric analysis of a new shade guide designed primarily for the visual evaluation of tooth whitening efficacy and to compare this shade guide with two commercial shade guides. Materials and Methods:, Color ranges and color distribution of three shade guides (prototype of the new Vita Bleachedguide 3D-Master [BG, Vita Zahnfabrik, Bad Säckingen, Germany], value scale of Vitapan Classical [VC, Vita], and color-ordered Trubyte Bioform porcelain shade guide [TB, Dentsply International, York, PA, USA]) were analyzed (N=3). A circular area (d=1.7 mm) on the middle of the labial surface of the tab, excluding the cervical portion, was measured with a spectroradiometer (D65, 2). Whiteness and yellowness indices were computed. Data were analyzed by analysis of variance and Fisher's PLSD test at a 0.05 level of significance. Results:, The range of color difference (,E*) from the lightest to the darkest tab was 33.8 (BG), 17.1 (VC), and 23.2 (TB). Mean values of ,E* among pairs of adjacent tabs were 3.0 (BG), 4.2 (VC), and 3.3 (TB). BG exhibited the highest R2 values between color coordinate pairs and between whiteness and yellowness indices with the respective color coordinates. Conclusions:, BG exhibited the widest color range and had the most consistent color distribution as compared with the two commercial products. Extension of the lightness range of BG toward higher L* values (bleach shades) was confirmed. CLINICAL SIGNIFICANCE A dental shade guide that is colorimetrically uniform might increase the reliability of visual comparisons of tooth whitening efficacy, whereas the inclusion of realistic bleaching shades in the shade guide will complement contemporary esthetic dentistry. (J Esthet Restor Dent 19:276,283, 2007) [source] | |||||||||||||