CNT-filled polypropylene/plasticized polyvinyl alcohol mixtures: rheology, morphology, and properties of composite threads

The influence of the concentration of plasticizer (glycerine) and carbon nanotubes (CNTs) on the micro- and macrorheological properties of melts of polypropylene/plasticized polyvinyl alcohol (PP/PVA) mixtures is studied. During flow of melts of all the studied compositions, a microfibrillar structure is formed within them. As found, changing the ratio of viscoelastic properties of PP and PVA, when adding different amounts of modifying additives, allows us to adjust the mass fraction of types of structures (microfibrils, films, particles), as well as their dimensional characteristics. Reducing the average diameter of microfibrils from 2.7 to 1.2 μm and increasing their share from 84.3 to 96.8 wt.% in the initial and nanofilled mixtures, respectively, are achieved in a composition with similar values of viscosity and elasticity of the components. As shown, the melts of bi- and three-component systems are typical non-Newtonian fluids, and the viscosity of their melts is several times lower than ɳ of the initial components. The values of elasticity, judging by the equilibrium swelling of extrudates, are higher than for the starting polymers, and depend on the content of nanotubes. The ability to longitudinal deformation of the melt jet, which determines its fibre-forming properties, in composite systems is reduced, but remains sufficient for stable processing into threads on available process equipment. As established, the formed microfibrillary structure helps to improve the performance characteristics of composite monothreads due to the effect of self-reinforcement. Tensile strength and dimensional stability of threads obtained from a mixture containing 0.5 wt.% CNTs increase by 1.5 and 1.6 times, respectively.Вивчено вплив концентрації пластифікатора (гліцерину) та вуглецевих нанотрубок (ВНТ) на мікро- та макрореологічні властивості розтопів сумішей поліпропілен/пластифікований полівініловий спирт (ПП/ПВС). За течії всіх досліджених композицій в них формується мікрофібрилярна структура. Встановлено, що зміна співвідношення в’язкопружніх властивостей ПП і ПВС через додавання у них різної кількости модифікувальних добавок уможливлює реґулювати масову долю різновидів структур (мікрофібрили, плівки, частинки), а також їхні розмірні характеристики. Зменшення середнього діяметра мікрофібрил з 2,7 до 1,2 мкм і збільшення їхньої частки з 84,3 до 96,8 мас.% у вихідній і нанонаповненій сумішах відповідно досягнуто в композиції з близькими величинами в’язкости й еластичности компонентів. Показано, що розтопи бі- та трикомпонентних систем є типовими неньютонівськими рідинами, а в’язкість їхніх розтопів у декілька разів нижча за ɳ вихідних компонентів. Величини еластичности, судячи з показників рівноважного розбухання екструдатів, є вищими, ніж для вихідних полімерів, і залежать від вмісту нанотрубок. Здатність до поздовжньої деформації розтопу струменя, яка визначає його волокноутворювальні властивості, у композиційних систем понижується, але залишається достатньою для стабільної переробки у нитки на наявному технологічному обладнанні. Встановлено, що сформована мікрофібрилярна структура сприяє поліпшенню експлуатаційних характеристик композиційних монониток за рахунок ефекту самоармування. Розривна міцність і формостійкість ниток, одержаних із суміші, що містить 0,5 мас.% ВНТ, зростають в 1,5 і 1,6 рази відповідно

Thermally and organomodified montmorillonite as effective regulators of the structure formation process in polypropylene/polystyrene blends

The influence of the concentration of thermally and organomodified montmorillonite on the processes of structure formation in a blend of polypropylene/polystyrene (PP/PS) was studied. It is established that in nanofilled compositions, as well as in the original, is formed a microfibrillar structure, the dimensional characteristics of which depend on the content of the additive and the method of its modification. The investigated clays by content (0.2-2.0) wt. % by weight of polypropylene have a compatibilizing effect in the blend of PP/PS, which reduces the average diameter of microfibers by 1.6 times and increases the homogeneity of their distribution by diameter: statistical indicators decrease (standard deviation, variance, coefficient of variation). The modifying effect of thermally modified clay is higher – the improvement of the dimensional characteristics of PP microfibers is achieved at its minimum content in the blend (0.2 wt. %). The formation of anisotropic PP structures in the PS matrix and the relaxation of the accumulated stresses at the exit of the molding hole is the main factor that causes high values of the coefficient of swelling of the extrudates (4.0-7.7). The change in the microstructure of the extrudates of nanofilled systems during spinning depends on the composition of the blend and the method of modification of montmorillonite. The average diameters of microfibers decrease from 2.2 μm (in the original blend) to (1.3-2.0) μm (in threecomponent) depending on the content of additives. The ability to regulate the microstructure of incompatible polymer blends by introducing additives of thermally and organomodified montmorillonite will contribute to the creation of nanocomposites with controlled morphology, as well as new fine-fiber materials with improved filtering characteristics

Regularities of producing of nano-filled polypropylene microfibers

The research on the influence of the concentration of the combined nano-dispersing additive of titanium oxide / silica (TiO2/SiO2) on the rheological properties and the structure-formation processes in a mixture of polypropylene / co-poliamid (PP/CPA) has been conducted. Established that during the flow of melt the allocation of components on phases with the formation of liquid jets (PP microfiber) in the matrix spa takes place

Measurement of J/ψ→γηcJ/\psi\to\gamma\eta_{\rm c} decay rate and ηc\eta_{\rm c} parameters at KEDR

Using the inclusive photon spectrum based on a data sample collected at the $J/\psi$ peak with the KEDR detector at the VEPP-4M $e^+e^-$ collider, we measured the rate of the radiative decay $J/\psi\to\gamma\eta_{\rm c}$ as well as $\eta_{\rm c}$ mass and width. Taking into account an asymmetric photon lineshape we obtained $\Gamma^0_{\gamma\eta_{\rm c}}=2.98\pm0.18 \phantom{|}^{+0.15}_{-0.33}$ keV, $M_{\eta_{\rm c}} = 2983.5 \pm 1.4 \phantom{|}^{+1.6}_{-3.6}$ MeV/$c^2$, $\Gamma_{\eta_{\rm c}} = 27.2 \pm 3.1 \phantom{|}^{+5.4}_{-2.6}$ MeV.Comment: 6 pages, 3 figure

Precise measurement of RudsR_{\text{uds}} and RR between 1.84 and 3.72 GeV at the KEDR detector

The present work continues a series of the KEDR measurements of the $R$ value that started in 2010 at the VEPP-4M $e^+e^-$ collider. By combining new data with our previous results in this energy range we measured the values of $R_{\text{uds}}$ and $R$ at nine center-of-mass energies between 3.08 and 3.72 GeV. The total accuracy is about or better than $2.6\%$ at most of energy points with a systematic uncertainty of about $1.9\%$. Together with the previous precise $R$ measurement at KEDR in the energy range 1.84-3.05 GeV, it constitutes the most detailed high-precision $R$ measurement near the charmonium production threshold.Comment: arXiv admin note: text overlap with arXiv:1610.02827 and substantial text overlap with arXiv:1510.0266

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations