K2SiF6:Mn4+@K2SiF6 phosphor with remarkable negative thermal quenching and high water resistance for warm white LEDs

2021 ◽  
Vol 234 ◽  
pp. 117968
Author(s):  
Yuelan Li ◽  
Yan Yu ◽  
Xue Zhong ◽  
Youmiao Liu ◽  
Long Chen ◽  
...  
Keyword(s):  
Water Resistance ◽  
Thermal Quenching ◽  
High Water ◽  
White Leds

scholarly journals Enhanced Water Resistance of Recycled Newspaper/High Density Polyethylene Composite Laminates via Hydrophobic Modification of Newspaper Laminas

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 421
Author(s):  
Binwei Zheng ◽  
Weiwei Zhang ◽  
Litao Guan ◽  
Jin Gu ◽  
Dengyun Tu ◽  
...  
Keyword(s):  
Stearic Acid ◽  
Photoelectron Spectroscopy ◽  
Composite Laminates ◽  
High Density Polyethylene ◽  
Water Resistance ◽  
Laminated Composite ◽  
High Strength ◽  
High Water ◽  
High Density ◽  
X Ray

A high strength recycled newspaper (NP)/high density polyethylene (HDPE) laminated composite was developed using NP laminas as reinforcement and HDPE film as matrix. Herein, NP fiber was modified with stearic acid (SA) to enhance the water resistance of the NP laminas and NP/HDPE composite. The effects of heat treatment and SA concentration on the water resistance and tensile property of NP and composite samples were investigated. The chemical structure of the NP was characterized with X-ray diffractometer, X-ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared spectra techniques. The surface and microstructure of the NP sheets were observed by scanning electron microscopy. An expected high-water resistance of NP sheets was achieved due to a chemical bonding that low surface energy SA were grafted onto the modified NP fibers. Results showed that the hydrophobicity of NP increased with increasing the stearic acid concentration. The water resistance of the composite laminates was depended on the hydrophobicity of the NP sheets. The lowest value of 2 h water absorption rate (3.3% ± 0.3%) and thickness swelling rate (2.2% ± 0.4%) of composite were obtained when the SA concentration was 0.15 M. In addition, the introduction of SA can not only enhance the water resistance of the composite laminates, but also reduce the loss of tensile strength in wet conditions, which shows potential in outdoor applications.

scholarly journals Water-Resistant Latex Coatings: Tuning of Properties by Polymerizable Surfactant, Covalent Crosslinking and Nanostructured ZnO Additive

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 347
Author(s):  
Jana Machotová ◽  
Andréa Kalendová ◽  
Denisa Steinerová ◽  
Petra Mácová ◽  
Stanislav Šlang ◽  
...  
Keyword(s):  
High Performance ◽  
Water Resistance ◽  
High Water ◽  
Coating Performance ◽  
Polymerizable Surfactant ◽  
Ionic Crosslinking ◽  
Latex Coatings ◽  
Covalent Crosslinking ◽  
Coating Composition ◽  
Acrylic Latexes

This paper deals with the development of acrylic latexes providing high-performance water-resistant coatings. For this purpose, mutual effects of anionic surfactant type (ordinary and polymerizable), covalent intra- and/or interparticle crosslinking (introduced by allyl methacrylate copolymerization and keto-hydrazide reaction, respectively) and ionic crosslinking (provided by nanostructured ZnO additive) were investigated. The latexes were prepared by the standard emulsion polymerization of methyl methacrylate, butyl acrylate and methacrylic acid as the main monomers. The addition of surface-untreated powdered nanostructured ZnO was performed during latex synthesis, resulting in stable latexes comprising dispersed nanosized additive in the content of ca 0.9-1.0 wt.% (based on solids). The coating performance with emphasis on water resistance was evaluated. It was determined that the application of the polymerizable surfactant improved coating adhesion and water-resistance, but it wasn′t able to ensure high water-resistance of coatings. Highly water-resistant coatings were obtained provided that covalent intra- and interparticle crosslinking together with ionic crosslinking were employed in the coating composition, forming densely crosslinked latex films. Moreover, coatings comprising nanostructured ZnO additive displayed a significant antibacterial activity and improved solvent resistance.

Nanocrystalline Phosphors for Lighting and Detection Applications

2010 ◽  
Vol 654-656 ◽  
pp. 1130-1133 ◽  
Author(s):  
Christopher J. Summers ◽  
Hisham M. Menkara ◽  
Richard A. Gilstrap ◽  
Mazen Menkara ◽  
Thomas Morris
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Shell Growth ◽  
Stokes Shift ◽  
Thermal Quenching ◽  
High Sensitivity ◽  
In Situ Monitoring ◽  
White Leds ◽  
Sensing Applications ◽  
Improved Stability

We report the development of new nanoparticle phosphors and quantum dot structures designed for applications to enhance the color rendering and efficiency of high brightness white LEDs, as well as for bio-sensing applications. The intrinsic problem of self-absorption, high toxicity, and high sensitivity to thermal quenching of conventional quantum dot systems has prevented their adoption to LED devices. Doped Cd-free quantum dots may circumvent these issues due to their distinct Stokes shift and improved stability at high temperature. We report on the modification of Mn-doped ZnSe/ZnS core-shell quantum dots for application to the (blue diode + yellow emitter) white LED system. Band gap tuning for 460 nm excitation, inorganic shell growth and in-situ monitoring for enhanced efficiency, and analysis of thermal stability will are reported.

INFLUENCE OF STRUCTURE OF POLYMERIC MATRIX ON STRUCTURE AND PROPERTY PRIMING COVERINGS

2021 ◽  
pp. 50-58
Author(s):  
V.A. Kuznetsova ◽  
◽  
V.G. Zheleznyak ◽  
S.L. Lonskii ◽  
N.A. Kovrizhkina ◽  
...  
Keyword(s):  
Water Absorption ◽  
Epoxy Resin ◽  
Phase Structure ◽  
Water Resistance ◽  
High Water ◽  
Physicomechanical Properties ◽  
Structure And Property ◽  
Organic Silicon ◽  
To Receive ◽  
Kinetics Of

Adhesion, physicomechanical properties, and also kinetics of water absorption of priming coatings on basis the E-41 epoxy resin modified by liquid Thiokol 1 and by Laproxide AF, and also their phase structure are investigated. As hardeners of primer compositions organic silicon ammine ASOT-2 and low-molecular polyamide PO-200 has been used. It is shown that use of the reactive modifier Laproxide AF and hardener ASOT-2 in the epoxy and thiokol film-formers allows to receive priming coating with uniform finely divided phase structure with low porosity and high water resistance.

Luminescence properties of Mn4+ with high 2Eg level energy in the polyfluoride Na3Li3Sc2F12

2020 ◽  
Vol 49 (33) ◽  
pp. 11613-11617
Author(s):  
Hong Li ◽  
Yan Liu ◽  
Shu Tang ◽  
Lijun Luo ◽  
Qiang Zhou ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Thermal Quenching ◽  
Luminescence Properties ◽  
Level Energy ◽  
Red Emission ◽  
White Leds ◽  
Red Emitting Phosphor

Red-emitting phosphor Na3Li3Sc2F12:Mn4+ with the high 2Eg level energy shows intensive red emission accompanied with the high external quantum efficiency and thermal-quenching resistance for warm white LEDs.

Preparation and Characterization of Bio-Degradable Plastic from Banana Kepok Peel Waste

2020 ◽  
Vol 981 ◽  
pp. 132-137
Author(s):  
Suharno Rusdi ◽  
Ridwan A. Destian ◽  
Fitratur Rahman ◽  
Achmad Chafidz
Keyword(s):  
Water Resistance ◽  
Raw Materials ◽  
Human Life ◽  
Base Material ◽  
High Water ◽  
Plastic Waste ◽  
Banana Peel ◽  
Recycled Plastics ◽  
Almost All

Everyday human life cannot be separated from plastic. Almost all objects that are around us are made of plastic. In general, plastics are non-biodegradable, causing environmental problems caused by the increased volume of plastic waste. One way to overcome this is by recycling existing plastic waste. But the use of recycled plastics is very limited and considered inefficient because the process is more difficult and processing is more expensive than buying new plastic raw materials. Another alternative is to use bioplastics or biodegradable plastic. This plastic is more environmentally friendly because it is biodegradable or easily decomposed by microorganisms. Basically, bioplastics can be made from vegetable starches. In this study we will use starch extracted from banana peel waste as a base material for making bioplastics. In this research, glycerin which is used as a bioplastic adhesive or plasticizer will be used. Whether or not bioplastics depend on the resistance to water, the attractiveness of the bioplastics, the ability of the plastic to be decomposed by microorganisms. From this research, it is expected to produce bioplastics with high water resistance and high tensile strength and easy to decompose microorganisms.

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