Due to their excellent mechanical and thermal properties and medium resistance, epoxy/carbon nanotubes and nanocomposites have been widely used in many fields. However, the conventional thermosetting process is not only time- and energy-consuming, but also causes the agglomeration of nanofillers, which leads to unsatisfactory properties of the obtained composites. In this study, multi-walled carbon nanotubes (MWCNTs)/epoxy nanocomposites were prepared using UV photoinduced frontal polymerization (PIFP) in a rapid fashion. The addition of MWCNTs modified by a surface carboxylation reaction was found to enhance the impact strength and heat resistance of the epoxy matrix effectively. The experimental results indicate that with 0.4 wt % loading of modified MWCNTs, increases of 462.23% in the impact strength and 57.3 °C in the glass transition temperature were achieved. A high-performance nanocomposite was prepared in only a few minutes using the PIFP approach. Considering its fast, energy-saving, and environmentally friendly production, the PIFP approach displays considerable potential in the field of the fast preparation, repair, and deep curing of nanocomposites and coatings.
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http://dx.doi.org/10.3390/ma13245838 | DOI Listing |
Materials (Basel)
December 2020
Aviation Key Laboratory of Science and Technology on Life-Support Technology, Xiangyang 441000, China.
Due to their excellent mechanical and thermal properties and medium resistance, epoxy/carbon nanotubes and nanocomposites have been widely used in many fields. However, the conventional thermosetting process is not only time- and energy-consuming, but also causes the agglomeration of nanofillers, which leads to unsatisfactory properties of the obtained composites. In this study, multi-walled carbon nanotubes (MWCNTs)/epoxy nanocomposites were prepared using UV photoinduced frontal polymerization (PIFP) in a rapid fashion.
View Article and Find Full Text PDFRSC Adv
November 2020
Laboratoire de Photochimie et d'Ingénierie Macromoléculaires, Université de Haute Alsace 3b rue Alfred Werner 68093 Mulhouse France
A new combination of sulfonium salts has been investigated to cure opaque and thick carbon composite materials through photoinduced thermal frontal polymerization reaction. The photopolymerization occurs at the surface of the cycloaliphatic epoxide through the excitation of a triarylsulfonium salt and releases enough heat to decompose an alkyl-based sulfonium salt acting as a latent thermal initiator. Thus, a thermal front propagates into the medium leading to the polymerization of the whole sample.
View Article and Find Full Text PDFMacromol Rapid Commun
July 2017
Mäder Research, 130 rue de la Mer Rouge, 68200, Mulhouse, France.
Pyrylium salts combined with vinyl ethers are shown to act as new versatile dual-cure initiating systems for both photochemical and thermal initiation of oxirane monomers. The combination of both possibilities allows the curing of thick samples through photoinduced frontal polymerization. On the basis of quantum calculations and photochemical experiments, some clues are given about the reaction mechanisms involved.
View Article and Find Full Text PDFChronic experiments were made on 35 non-inbred male rats (200-250 g b.w.) to study functional and morphological consequences of photochemical thrombosis of frontal cortex vessels Defects in CNS function were assessed by conditioned reflexes of passive avoidance and behavior in open field tests.
View Article and Find Full Text PDFJpn J Psychiatry Neurol
December 1989
Department of Psychiatry and Neurology, Hokkaido University School of Medicine, Sapporo, Japan.
Coherence and cross-phase-spectral analysis of EEG were applied to photo-sensitive subjects to investigate the mechanism of the generalization of photo-induced paroxysms. Coherence values were high between frontal (F) and central (C) in resting records and between F-C in EEGs revealing harmonic responses, where the coherence values of F-O (occipital) were also high, and the waves of F preceded those of O. In cases of occipital-localized 3/6 Hz (poly) spike-waves, discharges of O preceded those of F.
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