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Hybrid Thermoplastic and Thermosetting Composites
Published in Sanjay Mavinkere Rangappa, Jyotishkumar Parameswaranpillai, Suchart Siengchin, Lothar Kroll, Lightweight Polymer Composite Structures, 2020
N. R. Singha, P. K. Chattopadhyay, M. Karmakar, H. Mondal
In contrast, for the preparation of the natural fiber-based fillers, size reduction is carried out by initial grinding of dry natural fibers, followed by pulverization in a pulverizing machine and sieving to separate micro fillers [21,22]. Notably, various pretreatments, such as cyanoethylation [33], acetylation [33], alkali treatment [27], and UV irradiation [28], as illustrated in Figure 6.2a, b, c, and d, respectively, are often pursued for improving the reinforcing abilities of natural fillers, including bamboo [27], jute [28], and sisal [33], in producing PE-based hybrid composites. In this regard, cyanoethylation is basically incorporation of cyanoethyl groups in sisal or any natural fiber by means of initial dewaxing of sisal fibers, followed by refluxing with acrylonitrile, acetone, and pyridine-catalyst at 60°C for 2 h. Thereafter, the treated fibers are washed with acetic acid and acetone, followed by washing with deionized water and vacuum drying. In contrast, acetylation of natural fiber is achieved via treatment of alkali-treated fibers with glacial acetic acid, acetic anhydride, and concentrated H2SO4, followed by the usual washing and drying.
Surface Modification and Activation of Wood
Published in David N.-S. Hon, Chemical Modification of Lignocellulosic Materials, 2017
The surface thermoplasticization of Sugi using etherification was also examined [3]. Acrylonitrile, allyl bromide, and benzyl chloride were used in the cyanoethylation, allylation, and benzylation of wood surfaces (Fig. 10). Cyanoethylation and benzylation produced thermoplasticized surfaces with high glossiness, but allylated surfaces did not exhibit this property. Cyanoe-thylated wood surfaces were a reddish brown color and showed high glossiness, Brinell hardness, and good ultraviolet light resistance, but they did not show any water resistance (Fig. 11). During cyanoethylation many complicated competing reactions [28] take place and hydrophilic subproducts may be produced. This may account for their poor water resistance. Furthermore, acrylonitrile, which is used in the cyanoethylation treatment, is very poisonous and any residual unreacted acrylonitrile remaining in the wood after treatment is dangerous to human health. For this reason, cyanoethylation of wood surfaces with acrylonitrile is unlikely to be commercialized.
Physical Properties of Individual Groundwater Chemicals
Published in John H. Montgomery, Thomas Roy Crompton, Environmental Chemicals Desk Reference, 2017
John H. Montgomery, Thomas Roy Crompton
Uses: Copolymerized with methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, or 1,1-dichloroethylene to produce acrylic and modacrylic fibers and high-strength fibers; ABS (acrylonitrile–butadiene–styrene) and acrylonitrile–styrene copolymers; nitrile rubber; cyanoethylation of cotton; synthetic soil block (acrylonitrile polymerized in wood pulp); manufacture of adhesives; organic synthesis; grain fumigant; pesticide; monomer for a semiconductive polymer that can be used similar to inorganic oxide catalysts in dehydrogenation of tert-butyl alcohol to isobutylene and water; pharmaceuticals; antioxidants; dyes and surfactants.
A review on DBU-mediated organic transformations
Published in Green Chemistry Letters and Reviews, 2022
Shashi Kanth Boddu, Najeeb Ur Rehman, Tapan Kumar Mohanta, Anjoy Majhi, Satya Kumar Avula, Ahmed Al-Harrasi
DBU can be synthesized from a lactam, azepan-2-one (1). N-Cyanoethylation of lactam is carried out using acrylonitrile in the presence of a potassium hydroxide as base to produce the nitrite, 2, which is reduced using Raney-nickel in the presence of NH3to give N-(3-aminopropyl)-azepan-2-one (3). The compound 3 further undergoes condensation in the presence of p-toluenesulphonic acid (p-TSA) to yield DBU (Scheme 2) (18,19).