Initiators
Mostrando 1-12 de 122 artigos, teses e dissertações.
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1. RING OPENING POLYMERIZATION OF L-LACTIDE WITH TWO DIFFERENT ZINC(II) PHENOXY-IMINE COMPLEXES AS INITIATORS
This article reports the synthesis of two zinc(II) complexes containing phenoxy-imine ligands and their application as initiators of bulk ring opening polymerization (ROP) of L-lactide (LLA). The phenoxy-imine ligands (L1 and L2) were obtained by condensation reactions of salicylaldehyde derivatives with 2,6-diisopropylaniline. The reactions of L1 and L2 wit
Quím. Nova. Publicado em: 18/07/2019
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2. Long-term bonding efficacy of adhesives containing benzodioxioles as alternative co-initiators
Abstract This study evaluated the three-year lifespan of the bond to dentin of experimental self-etch adhesives containing benzodioxole derivatives – 1,3-benzodioxole (BDO) and piperonyl alcohol (PA) – as co-initiator alternative to amines. Adhesive resins were formulated using Bis-GMA, TEGDMA, HEMA, camphorquinone and different co-initiators: BDO, PA or
Braz. oral res.. Publicado em: 11/10/2018
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3. Effect of blisters and rims on radial hydride precipitation in fuel elements under dry storage conditions
ABSTRACT Hydrogen enters in Zry clads during fuel element life in service; when hydrogen exceeds the terminal solid solubility, circumferential hydrides are precipitated. In the presence of thermal gradients, produced for instance by oxide spallation, localized concentration of hydrides - known as blisters - can be formed. Due to the fact that zirconium hydr
Matéria (Rio J.). Publicado em: 19/07/2018
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4. Synthesis and Application of Bimetallic Zinc(II) Phenoxy-Imine Complexes as Initiators for Production of Lactide Polymers
This article reports the synthesis of two bimetallic zinc(II) complexes containing phenoxy-imine ligands and their application as initiators of ring opening polymerization (ROP) of L-lactide (LA). The phenoxy-imine ligands were obtained from salicylaldehyde derivatives and 2,3,5,6-tetramethylphenylenediamine, yielding two bidentate regions per ligand. The re
J. Braz. Chem. Soc.. Publicado em: 2018-02
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5. End Functionalization by Ring Opening Polymerization: Influence of Reaction Conditions on the Synthesis of End Functionalized Poly(lactic Acid)
In this paper, chemical functionalization of poly(lactic acid) (PLA) was carried out by using of salicyl aldehyde (SAl) and salicylic acid (SAc) as co-initiators of ring opening polymerization (ROP). Two factorial designs (22) were performed to evaluate the effects of the lactide/catalyst and co-initiator/catalyst molar ratios on the content of aldehyde or c
J. Braz. Chem. Soc.. Publicado em: 2018-01
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6. AN ALTERNATIVE ROUTE TO PRODUCE STANDARDS FOR GEL PERMEATION CHROMATOGRAPHY USING NITROXIDE MEDIATED POLYMERIZATION
Abstract All over the world standards for Gel Permeation Chromatography (GPC) are produced using ionic polymerization. Standards are commercialized in a broad range of molecular weight and their dispersity (Ð) must be lower than 1.1. This work proposes the synthesis of polystyrene standards using Nitroxide Mediated Polymerization (NMP), an alternative techn
Braz. J. Chem. Eng.. Publicado em: 2017-01
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7. Waterborne hyperbranched alkyd-acrylic resin obtained by miniemulsion polymerization
Abstract Four waterborne hyperbranched alkyd-acrylic resins (HBRAA) were synthesized by miniemulsion polymerization from a hyperbranched alkyd resin (HBR), methyl methacrylate (MMA), butyl acrylate (BA) and acrylic acid (AA), by using benzoyl peroxide (BPO) and ammonium persulfate (AP) as initiators. The reaction between HBR and acrylic monomers was evidence
Polímeros. Publicado em: 08/12/2016
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8. PARTICLE NUCLEATION USING DIFFERENT INITIATORS IN THE MINIEMULSION POLYMERIZATION OF STYRENE
Abstract In miniemulsion polymerization, droplet nucleation is the key factor to ensure the production of polymer particles with a desired composition. The influence of the initiation on droplet nucleation is conflicting and it has not been completely considered. The result of employing different initiator systems on the nucleation mechanism and kinetics in
Braz. J. Chem. Eng.. Publicado em: 2015-03
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9. ESTUDO DA IMOBILIZAÇÃO DE LIPASE EM SÍLICA OBTIDA PELA TÉCNICA SOL-GEL
The objective of this work was the immobilization of the enzyme Candida antarctica lipase B (CAL B) using the sol-gel method of immobilization and three different initiators of the polymerization reaction: one acid (HCl), one basic (NH4OH) and the other nucleophilic (HBr). Tetraethylorthosilicate was used as the silica precursor. The influence of the additiv
Quím. Nova. Publicado em: 2015-03
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10. Electronic vs. Steric Hindrance Effects in Amine Ligands to Ru-Based Initiators for ROMP
Complexos do tipo [RuCl2(PPh3)2(amina)x], com NH2Ph (1; x = 2), NH2Bz (2; x = 2) and NHBuPh (3; x = 1) na presença de etildiazoacetato (EDA), foram aplicados em reações de polimerização via metátese por abertura de anel (ROMP) de norborneno (NBE), norbornadieno (NBD) e diciclopentadieno (DCPD). Rendimentos quantitativos de poliNBE foram obtidos a 50 °
J. Braz. Chem. Soc.. Publicado em: 2014-12
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11. On the Determination of a Scatter Factor for Fatigue Lives Based on the Lead Crack Concept
ABSTRACT: The lead crack concept is adopted as the basis for a new fatigue lifeing method using the safe life philosophy. As part of its management strategy, a full-scale fatigue test is conducted to identify high-risk locations in the airframe, and for each item the time for retirement or structural repair is dictated by the safe life limit. A scatter facto
J. Aerosp. Technol. Manag.. Publicado em: 2013-06
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12. Experimental study of impact energy absorption in aluminium square tubes with thermal triggers
This study presents an approach for the improvement of crashworthiness properties of aluminium tubular structures using initiators introduced through localized heating. The main objective of this approach is to improve the ability to absorb impact energy in a progressive and controlled manner by a local modification of material properties. Through a localize
Materials Research. Publicado em: 03/02/2012