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Production and Modification of PHA Polymers Produced from Long-Chain Fatty Acids
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Chris Dartiailh, Nazim Cicek, John L. Sorensen, David B. Levin
Click chemistry can be applied to the vinyl groups of mcl-PHA derived from unsaturated fatty acid substrates, which drastically increases the number of modification permutations. Click-ready mcl-PHA were first produced by converting PHOU to contain terminal R-group carboxylic acids, then by esterification with propargyl alcohol yielding a “clickable” terminal alkyne. The objective was to produce amphiphilic polymers through polyethylene glycol (PEG) grafting. PHA-g-PEG was produced using PEG-azide producing polymers using longer PEG oligomers than could be grafted with previous direct esterification methods, ultimately increasing the molecular weight and crystallinity of this copolymer [105]. The terminal alkyne produced enables copper-catalyzed azide-alkyne [3+2] cycloaddition (CuAAC) with molecules containing azide groups.
Amphiphiles from Poly(3-hydroxyalkanoates)
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Poly(3-hydroxyoctanoate-co-3-hydroxyundecenoate) (PHOU) is methanolyzed and its unsaturated side chains are quantitatively oxidized to carboxylic acid. Alkyne-containing “clickable” PHA is obtained by the esterification with propargyl alcohol [50]. A click reaction of propargyl terminated PHOU with the azide terminated PEG leads to a PHOU-PEG graft copolymer. Figure 3.6 renders the synthesis of a PHOU-g-PEG graft copolymer using an azide-acetylene click reaction. Synthesis of PHOU-g-PEG graft copolymer using azide-acetylene click reaction [50].
Chemical Analysis
Published in Rudolf Puffr, Vladimír Kubánek, Lactam-Based Polyamides, 2019
Božena Lánská, Jaroslav Stehlíček
The limited solubility of polyamides, especially of polyamide 12, considerably restricts the choice of the solvent. In 1947, Waltz and Taylor112,113 determined carboxylic groups of polyamide 66 in benzyl alcohol solutions; benzyl alcohol has been predominantly used up to this day. Phenol, cresol, a mixture of phenol with benzyl alcohol, propargyl alcohol, chloral hydrate-methanol, and 2,2,2-trifluoroethanol were also used.114-119 In all these solvents polymers dissolve to a limited extent. To reach a concentration in solution, which is necessary for the titrimetric determination, all polymers must be dissolved at temperatures above 100°C. Even so, this means that the titrated solutions have a very low concentration of carboxylic groups, viz., 10–7 mol/ml by order of magnitude. To make the accuracy of determination satisfactory, the solvent must be accordingly pure. Consumption of the titrant by acid impurities in the solvent should not exceed 10% of that by carboxylic groups in the sample; hence, the content of carboxylic groups in the solvent should be below 10–8 mol/ml. For benzyl alcohol, this means that it must be free of benzaldehyde, which is transformed into benzoic acid in an uncontrollable way. A suitable method of purification is seen in the disproportionation of aldehyde into alcohol and acid, which proceeds in an alkaline medium. After purification, benzyl alcohol must be kept under protection of an inert gas, to rule out further possible oxidation. Similarly, all operations of the titrimetric determination must be performed in a stream of inert gas, because otherwise blank consumption by the titration medium has no constant value but increases.
Enhancement method of CFRP with the non-hydrophobized cellulose nanofibers using aqueous electrodeposition solution
Published in Mechanics of Advanced Materials and Structures, 2022
Kazuaki Katagiri, Shinya Honda, Toshihiko Okumura, Shimpei Yamaguchi, Sonomi Kawakita, Kazuhiro Kume, Katsuhiko Sasaki
In this study, a cationic EDS containing a resin with an epoxy group (INSULEED 3030, Nippon Paint Co., Ltd., Osaka, Japan) was selected [16]. The constituents of EDS were the ionized sulfonium salts with epoxy groups, fine particles of epoxy resin, propargyl alcohol and water. The EDS solution was set pH 7.5–8.5. The solid concentration of resin in EDS was adjusted to 20 wt.%. The EDS has been widely used for the electrodeposition painting for automotive bodies. Conventional EDS was oil-based, and a blocking agent was required to separate a resin prepolymer and curing agent to prevent chemical reaction before energization [17]. However, in recent years, aqueous EDS has been developed to reduce the environmental impact. The EDS used in this study was aqueous, and sulfonium reduction reaction is employed, instead of a blocking agent that becomes VOCs.
EUROCORR 2020: ‘closing the gap between industry and academia in corrosion science and prediction’: part 4
Published in Corrosion Engineering, Science and Technology, 2021
D. J. Mills (University of Nottingham, UK) addressed, ‘Exploring green corrosion inhibitors using electrochemical noise measurements of corrosion in acidic conditions.’ ‘Green’ corrosion inhibitors derived from plant materials such as henna leaves, celery seeds and banana skins, provide alternatives to conventional corrosion inhibitors. Certain extracts contain electron-rich polar atoms, e.g. N, O, S and P which confer inhibition. However, it is difficult to predict effective reagents on a molecular basis. Electrochemical noise (ECN), a quick and non-invasive method, using the natural fluctuations that occur during corrosion, was used. Corrosion rates could be derived from Resistance noise (Rn). The instrument used (ProCoMeter) is an improvement on hitherto conventional methods. The corrosion of mild steel in 1 M HCl (typically used in the pickling industry) at room temperature, was studied. A comparison between using propargyl alcohol and using broccoli extract was reported.
Enhancement of the bending strength of I-shaped cross-sectional beam of CFRP by dispersing cellulose nanofibers without hydrophobic treatment on the surface
Published in Mechanics of Advanced Materials and Structures, 2021
Kazuaki Katagiri, Shinya Honda, Sayaka Minami, Shimpei Yamaguchi, Hirosuke Sonomura, Ozaki Tomoatsu, Sonomi Kawakita, Sohei Uchida, Masayuki Nezu, Mamoru Takemura, Yayoi Yoshioka, Katsuhiko Sasaki
An electro-activated deposition solution for precipitating an epoxy resin on the cathode, INSULEED 3030 (Nippon Paint Co., Ltd., Japan) was selected [16]. This solution is an aqueous system, which contains a sulfonium salt of polymer with epoxy groups and propargyl alcohol. A sulfonium reduction precipitation occurs and epoxy is precipitated on the cathode side by energization. It is believed that sulfur is interposed between the carbon and resin (vulcanizing bond). Therefore, unlike conventional electrodeposition solution, a blocking agent to prevent chemical reaction in the solution to separate an epoxy resin prepolymer and a curing agent is unnecessary. Thus, no void was generated due to the evaporation of the blocking agent, and there is no emission of VOC which becomes air pollutant. No metal catalyst is used in the electro-activated deposition reaction.