Graphite Dispersion. I. Spectrocolorimetric Characterization

2008 ◽  
Vol 59 (2) ◽  
pp. 226-230
Author(s):  
Sorin Radoiu
Keyword(s):  
Visible Light ◽  
Point Of View ◽  
Light Spectrum ◽  
Color Parameters ◽  
Acrylic Resins ◽  
Chromaticity Coordinate ◽  
Color Differences ◽  
Special Programs ◽  
Chromatic Coordinates ◽  
Chromatic Color

The aim of the present study is to characterize from the spectrocolorimetric point of view the graphite films dispersed in epoxy, chloral-rubber, polyurethane and acrylic resins. By using a HunterLab system the remission spectrum in the visible light spectrum (400 � 700 nm) of the resulted films was measured. With special programs, from the spectrum were calculated the color parameters L*, a*, b*, C*, h*, the total color differences in three chromatic color units DE*, DEcmc, the three chromatic coordinates X, Y, Z, the chromaticity coordinate y, black index (without coloured undertone) of the films My and black shade index (contribution of the coloured undertone), dM.

scholarly journals Photocatalytic Activity and Characterization of Carbon-Modified Titania for Visible-Light-Active Photodegradation of Nitrogen Oxides

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Chun-Hung Huang ◽  
Yu-Ming Lin ◽  
I-Kai Wang ◽  
Chun-Mei Lu
Keyword(s):  
Visible Light ◽  
Carbon Number ◽  
Red Light ◽  
Matrix Material ◽  
Carbon Sources ◽  
Impregnation Method ◽  
Light Spectrum ◽  
Precursor Molecule ◽  
Visible Light Active ◽  
Carbonate Species

A variety of carbon-modified titania powders were prepared by impregnation method using a commercial available titania powder, Hombikat UV100, as matrix material while a range of alcohols from propanol to hexanol were used as precursors of carbon sources. Rising the carbon number of alcoholic precursor molecule, the modified titania showed increasing visible activities ofNOxphotodegradation. The catalyst modified with cyclohexanol exhibited the best activities of 62%, 62%, 59%, and 54% for the totalNOxremoval under UV, blue, green, and red light irradiation, respectively. The high activity with long wavelength irradiation suggested a good capability of photocatalysis in full visible light spectrum. Analysis of UV-visible spectrum indicated that carbon modification promoted visible light absorption and red shift in band gap. XPS spectroscopic analysis identified the existence of carbonate species (C=O), which increased with the increasing carbon number of precursor molecule. Photoluminescence spectra demonstrated that the carbonate species suppressed the recombination rate of electron-hole pair. As a result, a mechanism of visible-light-active photocatalyst was proposed according to the formation of carbonate species on carbon-modified TiO2.

scholarly journals A Modular, Self-Assembling Metallaphotocatalyst for Cross Couplings Using the Full Visible-Light Spectrum

2020 ◽  
Author(s):  
Susanne Reischauer ◽  
Volker Strauss ◽  
Bartholomäus Pieber
Keyword(s):  
Titanium Dioxide ◽  
Visible Light ◽  
Excited States ◽  
Catalyst System ◽  
Chemical Energy ◽  
Modular Approach ◽  
Nickel Catalysis ◽  
Light Spectrum ◽  
Dye Sensitized ◽  
Self Assembling

The combination of nickel- and photocatalysis has unlocked a variety of cross couplings. These protocols rely on a few photocatalysts that can only convert a small portion of visible light (<500 nm) into chemical energy. Many dyes that absorb a much broader spectrum of light are not applicable due to their short-lived excited states. Here we describe a self-assembling catalyst system that overcomes this limitation. The modular approach combines nickel catalysis with dye-sensitized titanium dioxide and can be used to catalyze various bond formations. <br>

Siliconic and Acrylic Resins Dispersed in Water as Protectives for Stone Surface

1992 ◽  
Vol 267 ◽  
Author(s):  
Guido Biscontin ◽  
P. Maravelaki ◽  
E. Zendri ◽  
A. Glisenti
Keyword(s):  
Contact Angle ◽  
Protective Effect ◽  
Water Absorption ◽  
Water Repellency ◽  
Point Of View ◽  
General Effect ◽  
Pore Filling ◽  
Complete Wetting ◽  
Vapour Permeability ◽  
Acrylic Resins

The aim of the present work is to compare the protective effect of solvent and water dispersed products on marble, Lecce and Istria stones. This choice is justified by the need of products effective also from the ecological and toxicological point of view. To obtain these informations two tests have been chosen: contact angle and water absorption. The contact angle may, in theory, be considered a measure of the water repellency, since complete wetting implies a contact angle of 0° and absolutely no wetting an angle of 180°. This does not apply to the water absorption by capillarity test because the absorption variation may be caused by either the water repellency action of the treatments or by the pore filling. However this test may give practical information about the general effect of the treatments. Moreover, the effect of treatments on permeability was investigated by vapour permeability test. Protective effect was studied after application of the products and at various stages of artificial weathering.

Rutile TiO2(011)-2 × 1 Reconstructed Surfaces with Optical Absorption over the Visible Light Spectrum

2016 ◽  
Vol 8 (40) ◽  
pp. 27403-27410 ◽  
Author(s):  
Rulong Zhou ◽  
Dongdong Li ◽  
Bingyan Qu ◽  
Xiaorui Sun ◽  
Bo Zhang ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Visible Light ◽  
Light Spectrum ◽  
Rutile Tio2 ◽  
Reconstructed Surfaces

scholarly journals Influence of White Reference Measurement and Background on the Color Specification of Orange Juices by Means of Diffuse Reflectance Spectrophotometry

2006 ◽  
Vol 89 (2) ◽  
pp. 452-457 ◽  
Author(s):  
Antonio J Melndez-Martnez ◽  
Isabel M Vicario ◽  
Francisco J Heredia
Keyword(s):  
Analysis Of Variance ◽  
Orange Juice ◽  
Diffuse Reflectance ◽  
The Other ◽  
Reflectance Spectrophotometry ◽  
Reference Measurement ◽  
Color Parameters ◽  
Color Differences ◽  
Color Specification

Abstract The color of citrus beverages, in general, is related to the consumers' perception of flavor, sweetness, and other characteristics related to the quality of these products, so it is important to develop suitable methods for accurately assessing this attribute. In this study, the color of 2 different kinds of orange juices (ultrafrozen orange juices and orange juices from concentrate) were measured using different white references in order to demonstrate the influence of white reference measurement on the color parameters obtained. The results of this work indicated that the election of a wrong white reference measurement can affect dramatically the accuracy of the objective specification of orange juice color. Thus, the application of analysis of variance ( = 0.01) revealed that, in most cases, the parameters obtained were significantly different. In terms of color differences, the change of the background for the same white reference affected the measurements less than the changes of white references for the same background. On the other hand, important chromatic differences between the 2 types of orange juices studied were found.

scholarly journals Influence of a cobalt-chromium metal framework on surface roughness and Knoop hardness of visible light-polymerized acrylic resins

2006 ◽  
Vol 14 (3) ◽  
pp. 208-212 ◽  
Author(s):  
Joane Augusto de Souza Júnior ◽  
Renata Cunha Matheus Rodrigues Garcia ◽  
Juliana Silva Moura ◽  
Altair Antoninha Del Bel Cury
Keyword(s):  
Visible Light ◽  
Diamond Particle ◽  
In Vitro Study ◽  
Knoop Hardness ◽  
Water Bath ◽  
Cobalt Chromium ◽  
Significance Level ◽  
Acrylic Resins ◽  
Metal Framework

Although visible light-polymerized acrylic resins have been used in removable partial dentures, it is not clear whether the presence of a metal framework could interfere with their polymerization, by possibly reflecting the light and affecting important properties, such as roughness and hardness, which would consequently increase biofilm accumulation. The aim of this study was to compare the roughness and Knoop hardness of a visible light-polymerized acrylic resin and to compare these values to those of water-bath- and microwave-polymerized resins, in the presence of a metal framework. Thirty-six specimens measuring 30.0 x 4.0 ± 0.5 mm of a microwave- (Onda Cryl), a visible light- (Triad) and a water-bath-polymerized (Clássico) (control) acrylic resins containing a cobalt-chromium metal bar were prepared. After processing, specimens were ground with 360 to 1000-grit abrasive papers in a polishing machine, followed by polishing with cloths and 1-µm diamond particle suspension. Roughness was evaluated using a profilometer (Surfcorder SE 1700) and Knoop hardness (Kg/mm²) was assayed using a microhardness tester (Shimadzu HMV 2000) at distances of 50, 100, 200, 400 and 800 µm from the metal bar. Roughness and Knoop hardness means were submitted to two-way ANOVA and compared by Tukey and Kruskal Wallis tests at a 5% significance level Statistically significant differences were found (p<0.05) for roughness and Knoop hardness, with light-polymerized resin presenting the highest values (Ra = 0.11 µm and hardness between 20.2 and 21.4 Kg/mm²). Knoop values at different distances from the metal bar did not differ statistically (p>0.05). Within the limitations of this in vitro study, it was concluded that the presence of metal did not influence roughness and hardness values of any of the tested acrylic resins.

scholarly journals Additives for Ambient 3D Printing with Visible Light

2021 ◽  
Author(s):  
Dowon Ahn ◽  
Lynn Stevens ◽  
Kevin Zhou ◽  
Zachariah Page
Keyword(s):  
3D Printing ◽  
Visible Light ◽  
Reaction Times ◽  
High Energy ◽  
Energy Methods ◽  
Mechanical Responses ◽  
Violet Light ◽  
Acrylic Resins ◽  
Printing Processes ◽  
Made In

With 3D printing we desire to be “limited only by our imagination”, and although remarkable advancements have been made in recent years the scope of printable materials remains narrow compared to other forms of manufacturing. Light-driven polymerization methods for 3D printing are particularly attractive due to unparalleled speed and resolution, yet the reliance on high energy UV/violet light in contemporary processes limits the number of compatible materials due to pervasive absorption, scattering, and degradation at these short wavelengths. Such issues can be addressed with visible light photopolymerizations. However, these lower-energy methods often suffer from slow reaction times and sensitivity to oxygen, precluding their utility in 3D printing processes that require rapid hardening (curing) to maximize build speed and resolution. Herein, multifunctional thiols are identified as simple additives to enable rapid high resolution visible light 3D printing under ambient (atmospheric O<sub>2</sub>) conditions that rival modern UV/violet-based technology. The present process is universal, providing access to commercially relevant acrylic resins with a range of disparate mechanical responses from strong and stiff to soft and extensible. Pushing forward, the insight presented within this study will inform the development of next generation 3D printing materials, such as multicomponent hydrogels and composites.

scholarly journals Additives for Ambient 3D Printing with Visible Light

2021 ◽  
Author(s):  
Dowon Ahn ◽  
Lynn Stevens ◽  
Kevin Zhou ◽  
Zachariah Page
Keyword(s):  
3D Printing ◽  
Visible Light ◽  
Reaction Times ◽  
High Energy ◽  
Energy Methods ◽  
Mechanical Responses ◽  
Violet Light ◽  
Acrylic Resins ◽  
Printing Processes ◽  
Made In

With 3D printing we desire to be “limited only by our imagination”, and although remarkable advancements have been made in recent years the scope of printable materials remains narrow compared to other forms of manufacturing. Light-driven polymerization methods for 3D printing are particularly attractive due to unparalleled speed and resolution, yet the reliance on high energy UV/violet light in contemporary processes limits the number of compatible materials due to pervasive absorption, scattering, and degradation at these short wavelengths. Such issues can be addressed with visible light photopolymerizations. However, these lower-energy methods often suffer from slow reaction times and sensitivity to oxygen, precluding their utility in 3D printing processes that require rapid hardening (curing) to maximize build speed and resolution. Herein, multifunctional thiols are identified as simple additives to enable rapid high resolution visible light 3D printing under ambient (atmospheric O<sub>2</sub>) conditions that rival modern UV/violet-based technology. The present process is universal, providing access to commercially relevant acrylic resins with a range of disparate mechanical responses from strong and stiff to soft and extensible. Pushing forward, the insight presented within this study will inform the development of next generation 3D printing materials, such as multicomponent hydrogels and composites.

Sign in / Sign up

Export Citation Format

Share Document