DOCSLIB.ORG

Understanding Pigments: the Third Step to Higher Quality And

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Understanding Pigments: the Third Step to Higher Quality And Understanding Pigments: The Third Mark Harber October, 2000 Step to Higher Quality and Consistency Putting great color in your product is part of the pigments. However, they are less opaque and systems approach for resolving issues of sub- would have to be used at higher loading levels to standard properties and appearance. achieve similar whiteness and opacity. This article on pigments is the third in a four-part Titanium Dioxide is used in the majority of the series about the interrelationship of the material products made by the cast polymer industry. Tita- components used in marble and solid surface nium Dioxide-based colors include most whites, manufacturing. These AOC-authored articles re- pastels, earth tones and off-whites such as bone, spond to the challenge that the cast polymer in- ivory, beige or biscuit. As noted in Table 1, non- dustries aspire to higher standards of quality and white synthetic oxides are combined with Titani- consistency. Because resolving cast polymer is- um Dioxide to create pastels and earth tones for sues requires a systems approach, other articles cultured marble and solid surface applications. in this series address resins, gel coats and pro- cessing. All articles begin with background infor- Phthalocyanine pigments, or "Phthalos," impart mation on the main subject matter, followed by deep colors such as the automotive "Hunter ten related issues and guidelines. Green" of a sport utility vehicle or the high strength Blue used in ballpoint pens. Because A BACKGROUND ON COLORANTS they are so deep when used by themselves, In their natural state, cast polymer resins meet a Phthalo Blue and Phthalo Green are normally variety of performance requirements but are lack- blended with other pigments, many times Titani- ing in the color that draws the customer to the um Dioxide. end product. Achieving a marketable color re- quires the addition of one or more pigments. Among black pigments, Iron Oxide Black is used Each pigment type or chemistry has an inherent to achieve a "jet" black look in cast polymer prod- property for imparting color to the final formula- ucts. Carbon blacks are used judiciously in many tion. Gray and Platinum colors, and as a shading com- ponent in many other formulations. Ultramarine Most of the primary pigments used in the cast blues, which have a deep "royal blue" color, can polymer industry are listed in Table 1. The first be blended with Titanium Dioxide to create the pigment listed, Titanium Dioxide, is often referred appearance of "Bright White" colors. to as "tee-eye-oh-two" after its chemical symbol, TiO2. Titanium dioxide is the most widely used ANALYZING COLOR AND CONSISTENCY white pigment because of its unique ability to pro- At AOC, scientists and technicians generally em- vide exceptional opacity and to lend whiteness ploy the CIE L*a*b* Color Scale for analyzing col- and brightness. Because of this opacity property, or. The Scale is a three-dimensional "map" that Titanium Dioxide is better able to "hide" the color determines the location of a specific color by lo- of the base resin than other commercially availa- cating the intersection of three different axes of ble white pigments. For example, Zinc Oxide (ZnO) color values. By using this system, a color analyst or zinc sulfide (ZnS) can be employed as white can numerically express or analyze if a product's Understanding Pigments, continued color is on target or if it is getting too blue or yel- 2. Dry or wet...the choice is yours. low, too green or red, too light or dark. See the For some operations, adding dry pigment to the sidebar report, "The CIE L*a*b* Scale 'Elevator,'" cast polymer batch can be cost and performance for details on this color evaluation system. effective. However, dry pigment addition is much less "forgiving" of formulation and process varia- While several different instruments are available tion. In dry form, a pigment is usually in a small for measuring color, visual assessment is still a particle size and irregular shape that causes it to very powerful and important technique. Cast poly- stick on equipment and workers. Without strict mers are not the only products where sight is attention to bin and hopper design, the handling used to make a subjective appraisal. Thus it is of solid pigments can lead to "bridging" and "rat- important the human observer agrees with and holing" problems. General maintenance and up- sophisticated color computer. Many important keep are also increased. purchasing decisions, such as homes, clothes and automobiles, are influenced entirely by visual Dry pigments take longer to blend into the cast color assessment. polymer system to ensure uniform distribution of color and to eliminate the possible appearance of GUIDELINES TO BETTER COLOR undispersed pigment specks. Furthermore, the Establishing color parameters and maintaining resin adsorption characteristics of dry pigments color consistency is a complex proposition. A list can lead to variations in gel time, higher catalyst of basic troubleshooting tips has a useful purpose demand and differences in green strength devel- but do not always address individual shop prefer- opment. ences and routines. In an alternative approach, let's look at key issues and guidelines for optimiz- Most operations prefer the convenience, simplici- ing color quality and consistency. These guide- ty and effectiveness of liquid or paste pigment lines are not presented in any particular order of dispersion. With pigment dispersions, the color is importance. suspended in a "vehicle" of monomer free polyes- ter resin. When added to the matrix resin of a Three of these guidelines - on record keeping, casting formulation, the dispersion gives the fin- manufacturing repeatability, and communicating ished part molded-in color. In pigment disper- with your suppliers - may look familiar. These uni- sions, potential clumps of solid color concentrate versal principles are important enough to be in- are broken down by high-shear premixing. cluded in all four articles of this series. The wet dispersion is easily added and blended 1. Judging the color that meets the eye. into the overall formulation for easier mainte- The way a color is judged can vary by the lighting nance of color consistency from run to run. environment. The same sample will take on a different appearance under a conventional incan- This is especially important for "mix and match" descent light bulb, outdoor daylight, and fluores- components, such as a back splash that is pro- cent office lighting. There are even more variables duced at a different time and with a different to consider for a company that has more than one batch than a vanity. visual inspector and when color-critical parts are manufactured and shipped from several loca- 3. Veining without or with monomer. tions. Shop workers take pride in developing techniques that create just the right effect with veining The appearance of some parts may change simp- pastes. When veining pastes are supplied without ly by changing the angle of illuminating light. Nor- styrene monomer, the resulting veins tend to be mal wear, scuffing, chalking or surface erosion on more subdued. Veining pastes supplied with mon- a part can also significantly alter the way overall omer tend to be bolder and brighter. However, the color and appearance is judged. Surface gloss monomer-containing paste calls for closer atten- plays a huge role in the perceiving color and ap- tion to reaction and cure to ensure consistency pearance of finished parts. and quality. Understanding Pigments, continued 4. Master the art and science of blending. es, changing the vehicle chemistry may be the Quality is improved when there is a greater under- most effective way to minimize the impact anoth- standing of the individual and total contributions er change would have on existing shop prefer- of resin, catalyst, filler and pigment. To ensure ences and practices. formulation consistency, it is best to maintain consistent parameters for the mixing procedure. 8. Put it in writing. This includes: the order of ingredient addition, the Good record keeping starts by saving the manu- time of addition, the length of each ingredient facturing and quality control records that your pig- blending cycle, and the temperature during addi- ment supplier provides. Combine that information tion. Part quality is also enhanced when ingredi- with a record of any variables that may affect ents are blended with clean and well maintained profitability and customer-acceptance. Keep a equipment. record of how changes and variations in the for- mulation and process affect the original optimized 5. Optimize your formulation for color. formulation. Test the pigment you intend to use at differing levels to achieve the best balance of cost and ap- 9. Seek repeatability, and repeat it. pearance. A general rule of thumb is to make and The key to color consistency is establishing con- compare test specimens at 0.25% increments sistency in your formulation and shop conditions. (0.25%, 0.50%, 0.75%, 1.00%, etc.). While higher In a never-ending quest for improvement, you can pigment loading will help reduce color variability, make methodical and incremental changes to pigment loadings are generally held to less than determine which factors increase quality, con- 2%. If any changes are made to a formulation, sistency and productivity. test the proposed formulation against the current formulation. 10. Talk to your material suppliers. Take advantage of outside technical expertise. A 6. Not all pigments, resins, catalysts and fillers professional technical service representative can are created equal. help you avoid or minimize "trial and error." Mak- Every ingredient in a cast polymer formulation ing good parts sooner saves time and money. Be contributes to the color of the final part. It is ex- specific about the make-up of your formulation tremely rare to find a "drop-in" replacement for an and details about your process and shop.
Load more

Recommended publications
  • Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 11
    This PDF is available from The National Academies Press at http://www.nap.edu/catalog.php?record_id=13374 Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 11 ISBN Committee on Acute Exposure Guideline Levels; Committee on 978-0-309-25481-6 Toxicology; National Research Council 356 pages 6 x 9 PAPERBACK (2012) Visit the National Academies Press online and register for... Instant access to free PDF downloads of titles from the NATIONAL ACADEMY OF SCIENCES NATIONAL ACADEMY OF ENGINEERING INSTITUTE OF MEDICINE NATIONAL RESEARCH COUNCIL 10% off print titles Custom notification of new releases in your field of interest Special offers and discounts Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the National Academies Press. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Request reprint permission for this book Copyright © National Academy of Sciences. All rights reserved. Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 11 Committee on Acute Exposure Guideline Levels Committee on Toxicology Board on Environmental Studies and Toxicology Division on Earth and Life Studies Copyright © National Academy of Sciences. All rights reserved. Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 11 THE NATIONAL ACADEMIES PRESS 500 FIFTH STREET, NW WASHINGTON, DC 20001 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Insti- tute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.
    [Show full text]
  • Nitrogen Dioxide
    Common Name: NITROGEN DIOXIDE CAS Number: 10102-44-0 RTK Substance number: 1376 DOT Number: UN 1067 Date: May 1989 Revision: April 2000 ----------------------------------------------------------------------- ----------------------------------------------------------------------- HAZARD SUMMARY * Nitrogen Dioxide can affect you when breathed in. * If you think you are experiencing any work-related health * Nitrogen Dioxide may cause mutations. Handle with problems, see a doctor trained to recognize occupational extreme caution. diseases. Take this Fact Sheet with you. * Contact can irritate and burn the skin and eyes with * Exposure to hazardous substances should be routinely possible eye damage. evaluated. This may include collecting personal and area * Breathing Nitrogen Dioxide can irritate the nose and air samples. You can obtain copies of sampling results throat. from your employer. You have a legal right to this * Breathing Nitrogen Dioxide can irritate the lungs causing information under OSHA 1910.1020. coughing and/or shortness of breath. Higher exposures can cause a build-up of fluid in the lungs (pulmonary edema), a medical emergency, with severe shortness of WORKPLACE EXPOSURE LIMITS breath. OSHA: The legal airborne permissible exposure limit * High levels can interfere with the ability of the blood to (PEL) is 5 ppm, not to be exceeded at any time. carry Oxygen causing headache, fatigue, dizziness, and a blue color to the skin and lips (methemoglobinemia). NIOSH: The recommended airborne exposure limit is Higher levels can cause trouble breathing, collapse and 1 ppm, which should not be exceeded at any even death. time. * Repeated exposure to high levels may lead to permanent lung damage. ACGIH: The recommended airborne exposure limit is 3 ppm averaged over an 8-hour workshift and IDENTIFICATION 5 ppm as a STEL (short term exposure limit).
    [Show full text]
  • Emerging Technology
    INDUSTRY NEWS EMERGING TECHNOLOGY Iron-based superconductors reinforce link to magnetism BRIEFS A new class of iron-oxyarsenide-based superconductors discovered earlier this year shares IDES Inc., a plastic similar unusual magnetic properties with previously known high-temperature superconductors materials information based on copper-oxide materials, report researchers at the National Institute of Standards and management company, Technology, Gaithersburg, Md. The work emphasizes a critical but as yet unexplained link be- and Firehole Technologies Inc., a tween magnetism and high-temperature superconductors. developer of innovative The importance of magnetism to high-temperature superconductors is remarkable because simulation technologies magnetism strongly interferes with conventional, low-temperature superconductors, but now for composite materials may prove to be an integral element of such materials. and structures, have The team used neutron beams to demonstrate that, like copper-oxide superconductors, the entered into a strategic new iron-oxyarsenide HTc materials discovered by Japanese researchers share an unusual partnership to develop a magnetic structure with magnetically active layers interspersed with layers of nonmagnetic searchable composite material. materials database. For more information: Qingzhen Huang, National Institute of Standards & Technology, 100 www.ides.com Bureau, Gaithersburg, MD 20899; tel: 301/ 975-6164; [email protected]; www.nist.gov. Intel Corp., Samsung Electronics, Copper nanowire arrays grown on different surfaces and Taiwan A simple process to grow upright copper nanowires on a variety of materials is under develop- Semiconductor ment by researchers at the University of Illinois in Urbana Champaign. The nanowire arrays Manufacturing could be suitable for field-emission displays, a new type of display technology that promises to pro- Company (TSMC) vide brighter, more vivid pictures than ex- have reached agreement on the need for industry- isting flat-panel displays.
    [Show full text]
  • The Oxidation of Carbon Monoxide Using a Tin Oxide
    THE OXIDATION OF CARBON MONOXIDE USING A TIN OXIDE CATALYST Christopher F. Sampson and Nicholas J. Gudde United Kingdom Atomic Energy Authority A.E.R.E. Harwell, Didcot, Oxon. United Kingdom SUMMARY This paper outlines some of the steps involved in the development by the United Kingdom Atomic Energy Authority (UKAEA) of a catalytic device for the recombination of carbon monoxide and oxygen in a C02 laser system. It contrasts the differences between CO oxidation for air purification and for laser environmental control, but indicates that there are similarities between the physical specifications. The principal features of catalytic devices are outlined and some experimental work described. This includes measurements concerning the structure and mechanical properties of the artifact, the preparation of the catalyst coating and its interaction with the gaseous environment. The paper concludes with some speculation about the method by which the reaction actually occurs. INTRODUCTION During the late 1970's, the United Kingdom Atomic Energy Authority at Harwell became involved in sol-gel technology as a result of oxide fuel development. The sol-gel method was found to be suitable for the preparation of catalytic materials which eventually led to their use in car exhaust catalytic converters and for air purification catalysts. Such catalysts were usually in the form of coatings applied to supporting artifacts such as monoliths, formed from either cordierite or from a corrosion resistant metal such as Fecralloy steel (R). The UKAEA has experience in the use of sol-gel catalysts for CO removal from air and so has a technological link to a system intended to recombine O2 and CO formed in sealed C02 lasers.
    [Show full text]
  • Zinc Oxide Sulfide Scavenger Contains a High-Quality Zinc Oxide
    ZINC OXIDE ZINC OXIDE sulfide scavenger contains a high-quality ZINC OXIDE. The very fine particle-size of ZINC OXIDE scavenger results in a maximum amount of surface area for fast, efficient sulfide scavenging. It reacts with sulfides (see APPLICATIONS below) to form ZnS. This precipitate is an insoluble, inert, fine solid that remains harmlessly in the mud system or is removed by the solids-control equipment. Typical Physical Properties Physical appearance ������������������������������������������������������������������������������������������������������������������������������������������������������������������������������ White to off-white powder Specific gravity .......................................................................................................................................................................................................................... 5.4 – 5.6 Bulk density ........................................................................................................................................................................................................ 164 lb/ft3 (2627 kg/m3) Applications Under operating conditions, ZINC OXIDE scavenger reacts with sulfides to form ZnS, as shown in these equations: Zn2+ + HS- + OH- → ZnS ↓ + 2+ 2- H2O Zn + S → ZnS ↓ INC XIDE Z O scavenger is effective at the pH levels found in drilling fluids. It is recommended that a pH above 11 be maintained whenever H2S is - 2- expected. This high alkalinity converts the dangerous H2S gas to less toxic bisulfide
    [Show full text]
  • Sulfur Dioxide Emissions
    Report on the Environment https://www.epa.gov/roe/ Sulfur Dioxide Emissions Sulfur dioxide (SO2) belongs to the family of sulfur oxide (SOx) gases. These gases are formed when fuel containing sulfur (mainly coal and oil) is burned (e.g., for electricity generation) and during metal smelting and other industrial processes. High concentrations of SO2 are associated with multiple health and environmental effects. The highest concentrations of SO2 have been recorded in the vicinity of large industrial facilities. SO2 emissions are an important environmental issue because they are a major precursor to ambient PM2.5 concentrations. Short-term exposure to airborne SO2 has been associated with various adverse health effects (ATSDR, 1998; U.S. EPA, 2017). Multiple human clinical studies, epidemiological studies, and toxicological studies support a causal relationship between short-term exposure to airborne SO2 and respiratory morbidity. The observed health effects have included respiratory symptoms, airway inflammation, and increased emergency department visits and hospitalizations for all respiratory causes. These studies further suggest that asthmatics, children, older adults, and people who spend a lot of time outdoors at increased exertion levels are potentially susceptible or vulnerable to these health effects (U.S. EPA, 2017). In addition, SO2 reacts with other air pollutants to form sulfate particles, which are constituents of fine particulate matter (PM2.5). Inhalation exposure to PM2.5 has been associated with various cardiovascular and respiratory health effects (see PM Concentrations indicator). Many other environmental effects are associated with high concentrations of SO2. For example, airborne SO2, along with nitrogen oxides (NOx), contributes to acidic deposition (the Acid Deposition indicator); SO2 is a major precursor to PM2.5 (the PM Concentrations indicator); and SO2 contributes to impaired visibility (the Regional Haze indicator).
    [Show full text]
  • Reduction of Nitrogen Oxides by Carbon Monoxide Over an Iron Oxide Catalyst Under Dynamic Conditions
    Applied Catalysis B: Environmental 17 (1998) 357±369 Reduction of nitrogen oxides by carbon monoxide over an iron oxide catalyst under dynamic conditions Harvey Randall, Ralf Doepper, Albert Renken* Institute of Chemical Engineering, Federal Institute of Technology, 1015 Lausanne, Switzerland Received 6 July 1997; received in revised form 23 November 1997; accepted 2 December 1997 Abstract The reduction of NO and N2O by CO over a silica-supported iron oxide catalyst was investigated by the transient response method, with different initial oxidation states of the catalyst, i.e. completely reduced (Fe3O4), or oxidised (Fe2O3). The in¯uence of CO pre-adsorption was also studied. From the material balance on the gas phase species, it was shown that the composition of the catalyst changes during relaxation to steady-state. The degree of reduction of the catalyst at steady-state could thus be estimated. During the transient period, CO was shown to inhibit N2O as well as NO reductions by adsorption on reduced sites. The activity of the reduced catalyst was found to be substantially higher as compared to the oxidised catalyst for both reactions. On this basis, it was attempted to keep the catalyst in a reduced state by periodically reducing it with CO. As a result, a signi®cant increase in the performance of the reactor with respect to steady-state operation could be achieved for N2O reduction by CO. Finally, the dynamic behaviour of the N2O±CO and NO±CO reactions made it possible to evidence reaction steps, the occurrence of which could not be shown during our previous investigations on the separate interactions of the reactants with the catalyst.
    [Show full text]
  • Superconducting Properties of the Oxygen-Vacant Iron Oxyarsenide
    Superconducting properties of the oxygen-vacant iron oxyarsenide TbFeAsO1- from underdoped to overdoped compositions Y.G. Sh i, 1,2,* S. Yu,3 A.A. Belik,1,2 Y. Mat sushi ta, 4 M. Tanaka,4 Y. Katsuya,5 K. Kobayashi,4 Y. Hata, 6 H. Yasuoka,6 K. Yamaura,2,3 E. Takayama-Muromachi1,2,3 1 International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan. 2 JST, Transformative Research-Project on Iron Pnictides (TRIP), Tsukuba, Ibaraki 305-0044, Japan. 3 Superconducting Materials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 Ibaraki, Japan 4 NIMS Beamline Station at SPring-8, National Institute for Materials Science, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan 5 SPring-8 Service Co. Ltd., 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan 6 Department of Applied Physics, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka 239-8686, Japan. Abstract A wide-range doping was achieved by a high-pressure method for TbFeAsO1- from “under doped” to “over doped” superconducting compositions throughout the optimized superconductivity (Tc of 44 K). Tc vs. shows a dome-shaped feature, while Tc vs. the lattice constant likely follows a unique empirical curve over the doping range. The relatively large amount of oxygen vacancies up to ~0.3 per the formula unit was introduced possibly because of the smaller replacement Tb than the other Ln (rare-earth element) in the LnFeAsO1- system. PACS: 74.62.Bf, 74.25.Dw, 74.70.Dd 1 Introduction Discovery of high-Tc superconductivity in the iron oxypnictide LnFeAsO probably caused one of the highest impacts in materials science since 1986, the year copper oxide superconductor was discovered [1,2].
    [Show full text]
  • Croconate Salts. New Bond-Delocalized Dianions, &Q
    JOURNAL OF RESEARCH of the National Bureau of Standards Volume 85, No.2, March·April1980 Pseudo-Oxocarbons. Synthesis of 2, 1,3-Bis-, and 1, 2, 3-Tris (Dicyanomethylene) Croconate Salts. New Bond-Delocalized Dianions, "Croconate Violet" and "Croconate Blue"* Alexander J. Fatiadit National Bureau of Standards, Washington, D.C. 20234 October 24,1979 Synthesis and characteri zation of new bond·delocalized dianions, e.g., 2, 1,3·bis·, 1,2, 3·tris (di cyanomethyl. ene) croconate salts have been described. The dianions re ported represent a new class of aromati c, nonbenze· noid co mpounds, named pseudo·oxocarbons. A study of their physical, analytical and chemical properties offer a new direction in the chemistry of oxocarbons. Key words: Acid; aromatic; bond·delocalized; croco nic; diani on; malononitrile; nonbenzenoid; oxocarbon; salt; synthesis 1. Introduction molecular properties of the croconic salts (e.g. 2 , dipotas­ sium salt) were first seriously investigated when a symmetri­ The bright ye ll ow dipotassium croconate 1 and croconic cal, delocalized structure fo r the dianion 2 was proposed by acid (1 , K = H, 4,5-dihydroxy-4--cyclopentene-l,2,3-trione) Yamada et aJ. [3] in 1958. A few years later [4], the d i anion 2 were first isolated by Gmelin [1]' in 1825, from the black, ex· and the related deltate [5], squarate, rhodizonate, and plosive, side-reaction product (e.g. K6 C6 0 6 + KOC=COK), tetrahydroxyquinone anions were recognized by West et aJ. by the reaction of carbon with potassium hydroxide, in a [2,4] as members of a new class of aromatic oxocarbons pioneer, industrial attempt to manufacture potassium.
    [Show full text]
  • Graphether：A Two-Dimensional Oxocarbon As a Direct Wide-Gap Semiconductor with High Mechanical and Electrical Performances
    Graphether：A Two-Dimensional Oxocarbon as a Direct Wide-Gap Semiconductor with High Mechanical and Electrical Performances Gui-Lin Zhu1‖, Xiao-Juan Ye1,2‖, and Chun-Sheng Liu1,2* 1Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China 2School of Engineering, University of British Columbia, Kelowna, BC V1V 1V7, Canada ‖The first two authors contributed equally to this work. *E-mail: [email protected] Abstract: Although many graphene derivatives have sizable band gaps, their electrical or mechanical properties are significantly degraded due to the low degree of π-conjugation. Besides the π-π conjugation, there exists hyperconjugation interactions arising from the delocalization of σ electrons. Inspired by the structural characteristics of a hyperconjugated molecule, dimethyl ether, we design a two-dimensional oxocarbon (named graphether) by the assembly of dimethyl ether molecules. Our first-principle calculations reveal the following findings: (1) Monolayer graphether possesses excellent dynamical and thermal stabilities as demonstrated by its favourable cohesive energy, absence of the soft phonon modes, and high melting point. (2) It has a direct wide-band-gap of 2.39 eV, indicating its potential applications in ultraviolet optoelectronic devices. Interestingly, the direct band gap feature is rather robust against the external strains (-10% to 10%) and stacking configurations. (3) Due to the hyperconjugative effect, graphether has the high intrinsic electron mobility. More importantly, its in-plane stiffness (459.8 N m-1) is even larger than that of 1 graphene. (4) The Pt(100) surface exhibits high catalytic activity for the dehydrogenation of dimethyl ether.
    [Show full text]
  • Titanium Dioxide
    Right to Know Hazardous Substance Fact Sheet Common Name: TITANIUM DIOXIDE CAS Number: 13463-67-7 Synonyms: Rutile; Anatase; Brookite Anatase Titanium Dioxide 1317-70-0 (powder form) Chemical Name: Titanium Oxide Rutile Titanium Dioxide 1317-80-2 (powder form) Date: July 2011 Revision: May 2016 RTK Substance Number: 1861 DOT Number: None Description and Use EMERGENCY RESPONDERS >>>> SEE LAST PAGE Titanium Dioxide is an odorless, white powder. It is used in Hazard Summary paints, cosmetics, plastics, paper and food. Hazard Rating NJDOH NFPA HEALTH 2 - FLAMMABILITY 0 - REACTIVITY 0 - CARCINOGEN Reasons for Citation POISONOUS GASES ARE PRODUCED IN FIRE. Titanium Dioxide is on the Right to Know Hazardous DOES NOT BURN Substance List because it is cited by OSHA, ACGIH, NIOSH and IARC. Hazard Rating Key: 0=minimal; 1=slight; 2=moderate; 3=serious; This chemical is on the Special Health Hazard Substance 4=severe List. Titanium Dioxide can affect you when inhaled. Titanium Dioxide should be handled as a CARCINOGEN-- WITH EXTREME CAUTION. Exposure can irritate the eyes, nose and throat. Titanium Dioxide can irritate the lungs. Repeated exposure may cause bronchitis to develop with coughing, phlegm, SEE GLOSSARY ON PAGE 5. and/or shortness of breath. FIRST AID Eye Contact Workplace Exposure Limits Immediately flush with large amounts of water for at least 15 OSHA: The legal airborne permissible exposure limit (PEL) is minutes, lifting upper and lower lids. Remove contact 15 mg/m3 averaged over an 8-hour workshift. lenses, if worn, while rinsing. NIOSH: The recommended airborne exposure limit (REL) is Skin Contact 2.4 mg/m3 for fine Titanium Dioxide, and 0.3 mg/m3 Remove contaminated clothing and wash contaminated skin for ultrafine Titanium Dioxide, averaged over a 10- with soap and water.
    [Show full text]
  • Download Article (PDF)
    Z. Kristallogr. 226 (2011) 435–446 / DOI 10.1524/zkri.2011.1363 435 # by Oldenbourg Wissenschaftsverlag, Mu¨nchen Structural chemistry of superconducting pnictides and pnictide oxides with layered structures Dirk JohrendtI, Hideo HosonoII, Rolf-Dieter HoffmannIII and Rainer Po¨ttgen*, III I Department Chemie und Biochemie, Ludwig-Maximilians-Universita¨t Mu¨nchen, Butenandtstraße 5–13 (Haus D), 81377 Mu¨nchen, Germany II Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan III Institut fu¨r Anorganische und Analytische Chemie, Universita¨t Mu¨nster, Corrensstraße 30, 48149 Mu¨nster, Germany Received October 29, 2010; accepted February 6, 2011 Pnictide / Pnictide oxide / Superconductivity / for hydride formation of CeRuSi ! CeRuSiH [6] and Intermetallics / Group-subgroup relation CeRuGe ! CeRuGeH [7]. The crystal chemical data of the huge number of ZrCuSiAs materials have recently Abstract. The basic structural chemistry of supercon- been reviewed [8]. ducting pnictides and pnictide oxides is reviewed. Crystal Although the basic crystallographic data of the many chemical details of selected compounds and group sub- ThCr2Si2 and ZrCuSiAs type compounds are known for group schemes are discussed with respect to phase transi- several years, especially for the ZrCuSiAs family, systema- tions upon charge-density formation, the ordering of va- tic property studies have been performed only recently. cancies, or the ordered displacements of oxygen atoms. These investigations mainly focused on p-type transparent Furthermore, the influences of doping and solid solutions semiconductors like LaCuSO (for a review see [9]) or the on the valence electron concentration are discussed in or- colored phosphide and arsenide oxides REZnPO [10] and der to highlight the structural and electronic flexibility of REZnAsO [11].
    [Show full text]