Harnessing the Melting Peculiarities of Ultra‐High Molecular Weight Polyethylene Fibers for the Processing of Compacted Fiber Composites

Summary: Compacted fiber composites offer unique properties due to their lack of an extraneous matrix. The conditions of processing ultra‐high molecular weight polyethylene (UHMWPE) fibers were simulated in a heated pressure cell. In situ X‐ray diffraction measurements were used to follow the relevant transitions and the changes in the degree of crystallinity during melting and crystallization. The results strongly support the suggestion that the hexagonal crystal phase, in which the chain conformation is extremely mobile on the segmental level, constitutes the physical basis of compaction technologies for processing UHMWPE fibers into a single‐polymer composite. This report suggests that using a pseudo‐phase diagram outlining the occurrence of different phases during slow heating and the degree of crystallinity can provide valuable insight into the technological parameters relevant for optimal processing conditions.

Degree of crystallinity as a function of pressure and temperature in a region relevant to compaction processes.     

Hydrogenation of Citral Over a Polymer Fibre Catalyst

A polymer-supported Pd catalyst was investigated in hydrogenation of citral (3,7-dimethyl-2,6-octadienal), which is a stereoisomer with an isolated and a conjugated double bond as well as a carbonyl group. The catalyst was a fibrous polymer-supported catalyst modified with functional groups and immobilized metals. A comparison of the polymer-supported catalyst with conventional catalysts was made.     

Furfural Oxidation with Hydrogen Peroxide Over ZSM-5 Based Micro-Mesoporous Aluminosilicates

Micro-mesoporous aluminosilicates based on ZSM-5 zeolite, obtained by a dual template method, as well as in the presence of a dual-functional template (i.e. a Gemini-type surfactant), were tested in the oxidation of furfural with hydrogen peroxide. Even substantial changes in acidity and porosity of the catalysts result in minor variations of selectivity towards the desired products. Application of the synthesized zeolite-based materials in the oxidation of furfural with hydrogen peroxide leads to formation of 2(5H)-furanone (yield up to 28.5%) and succinic acid (up to 19.5%) as the main C4 reaction products. The kinetic model developed previously to treat the results for oxidation of furfural over sulfated zirconia was able to describe the data also for micro-mesoporous aluminosilicates.

Graphical Abstract

     

Tuning fermi level and band gap in Li4Ti5O12 by doping and vacancy for ultrafast Li+ insertion/extraction

Li₄T_i5O₁₂ (LTO) attracts great interest due to the “zero strain” during cycles but the poor electronic and ionic conductivity critically impede the practical application. Herein, we report a synergy strategy of tuning localized electrons to shift Fermi level and band gap by Mg/Zr co-doping and oxygen vacancy incorporation, which significantly improves Li⁺ and electronic transport. More importantly, the intrinsic synergistic mechanism has been revealed by neutron diffraction, X-ray absorption spectra, and first-principles calculations. The “elastic effect” of lattice induced by Mg/Zr co-doping allows LTO to accommodate more oxygen vacancies to a certain degree without a severe lattice distortion, which largely improves the electronic conductivity. Mg/Zr co-doping and oxygen vacancy incorporation effectively enhanced the dynamic characteristics of LTO electrode, achieving the excellent rate performance (90 mAh/g at 20C) and cycle stability (96.9% after 500 cycles at 10C). First-principles calculations confirm Fermi level shifts to the conduction band, and the band gap becomes narrowed due to the synergistic modulation, and the intrinsic mechanism of the enhanced electronic and Li-ion conductivity is clarified. This study offers some insights into achieving the fast Li⁺ insertion/extraction by tuning the crystal and electronic structure with lattice doping and oxygen vacancy engineering.     

Synthesis of amphiphilic (meth)acrylates with oligo(ethylene glycol) and (or) oligo(propylene glycol) blocks by the esterification of (meth)acrylic acid

Thermoresponsive PEG-based (PEG stands polyethylene glycol) polymers are unique for use in medicine because of their low toxicity, good biocompatibility and biodegradability, but usually more hydrophobic and more toxic comonomers are used to adjust lower critical solution temperature (LCST). A convenient way to overcome this problem and to finely tune LCST is to use alkoxy oligo(ethylene glycol)- or alkoxy oligo(propylene glycol) (meth)acrylates as starting comonomers. Here we report on the conditions for the simple and affordable synthesis of methoxy oligo(propylene glycol) (meth)acrylate- and methoxy oligo(propylene glycol)-block-oligo(ethylene glycol) (meth)acrylate-based macromonomers with high yields (80%–98.7%) by the acid-catalyzed esterification of (meth)acrylic acid with alkoxy oligo(alkylene glycols) containing oligo(ethylene glycol) (OEG) and/or oligo(propylene glycol) (OPG) blocks. p-Toluene sulphonic acid (pTSA), alkyl(C₁₂–C₁₄)benzene sulfonic acid (ABSA) and H₂SO₄ were used as catalysts. It has been shown that pTSA and ABSA are practically the same in catalytic activity and are superior to sulfuric acid. The reaction orders with respect to catalyst was found to be close to 1 in all cases. It has been shown that the reaction is actually insensitive to the lengths of OEG and OPG blocks, as well as to the structure of the terminal alkyl group, while the esterification of acrylic acid (AA) proceeds much faster compared to methacrylic acid (MAA) one under the same conditions. The influence of temperature on the equilibrium conversions of alcohols was determined, which were found to be 89%–93% for the esterification of AA and 61%–86% for MAA in the temperature range of 60–120°C. A further increase in conversion was achieved by introducing an azeotropic agent (toluene), its optimal concentration was found to be 10%–15%.     

Methods of handling of in-bulk agglomeration layer image representation for granulometric composition assessment

The analysis of methods of images handling is carried out, the method of dynamic threshold division which is based on the calculation of weight coefficient of points in the local area is suggested. The method of adaptive adjustment of the size of the local area of the image representation is carried out to define the threshold value. Also methods of binary recursive filtration and mathematical morphology to reduce interference are introduced. The article is published in the original. Evgenii Valentinovich Ershov. The first pro-rector, head of the department of PC software, professor of the Cherepovetsk State University. Finished postgraduate studies at the North-Western Polytechnic Correspondence Institute (the city of St. Petersburg) in 1993 and defended a Ph.D. thesis on specialty 05.02.11 “Methods of Control and Diagnostics in Mechanical Engineering.” Circle of scientific interests: the development of methods and principles for the building of multi-functional technical vision systems, their mathematical and software support. Five postgraduate students defended theses under his supervision. Author of 170 scientific and teaching works, including 4 monographs, 85 articles, of which 12 were published in reviewed journals, 39 theses of reports, 2 reports on SRD, 3 patents. Took part in 20 scientific and technical conferences in Moscow, St. Petersburg, Cherepovetsk, Kursk, Tambov, Vologda, Tula, Krasnoyarsk, Yoshkar Ola, and Kemerovo. Vera Vital’evna Selivanovskikh. Docent of the department of PC software of the Cherepovetsk State University. Finished postgraduate studies at the Cherepovetsk State University on specialty “Solid-State Physics” in 2000 and began to study the problem of the optic-electronic control over the quality of metallurgical industry products. Defended a Ph.D. thesis on specialty 05.13.06 “Automation and Management of Technological Processes and Productions” in 2007. Author of more than 30 scientific and teaching works, including 1 monograph, 7 articles, of which 2 were published in reviewed journals, 13 theses of reports. Took part in the scientific and technical conferences in Moscow, Cherepovetsk, Kursk, Tambov, Vologda, Tula, Yoshkar Ola. Oksana Georgievna Ganicheva. Docent of the department of PC software of the Cherepovetsk State University. Finished postgraduate studies at the Cherepovetsk State University and defended a Ph.D. thesis on specialty 05.13.06 “Automation and Management of Technological Processes and Productions” in 2007. Circle of scientific interests: the development and perfecting of methods for the optic-electronic control over the quality of metallurgical industry products. Author of more than 30 scientific and teaching works, including 1 monograph, 7 articles, of which 2 were published in reviewed journals, 10 theses of reports. Took part in the scientific and technical conferences in Cherepovetsk, Kursk, Vologda, Tula, Yoshkar Ola.