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Search results for: isocyanate index
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THERMOMECHANICAL PERFORMANCE OF FLEXIBLE POLYURETHANE FOAMS AS A FUNCTION OF THE ISOCYANATE INDEX
PublicationPolyurethane foams are very versatile materials applied in different branches of industry. Their popularity is attributed, among others, to the flexibility in engineering their mechanical performance by the adjustment of their formulations. One of the most crucial factors is the isocyanate index, determining the ratio between the free hydroxyl and isocyanate groups present in the polyurethane system. By the change of this ratio,...
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Performance properties of rigid polyurethane-polyisocyanurate/brewers’ spent grain foamed composites as function of isocyanate index
PublicationIn the presented work, rigid polyurethane-polyisocyanurate (PUR-PIR) foams filled with brewers’ spent grain (BSG) were prepared. The influence of the isocyanate index (II) on its performance was investigated. Foams obtained with higher isocyanate index required a higher amount of hydrofluorocarbon physical blowing agent to provide the same apparent density of material. An increase of isocyanate index resulted in a slight decrease...
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The Impact of Isocyanate Index and Filler Functionalities on the Performance of Flexible Foamed Polyurethane/Ground Tire Rubber Composites
PublicationThe structure and performance of polyurethane (PU) foams are strongly driven by the stoichiometry of the polyaddition reaction, quantitatively described by the isocyanate index. It determines the balance between isocyanate and hydroxyl groups in the reacting system and is affected by the introduction of additional functionalities originated, e.g., from applied fillers. Nevertheless, this issue is hardly taken into account in research...
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Non-isocyanate Polyurethanes
PublicationThe main aim of this chapter is to present a general overview of the NIPU synthesis method (i.e., polycondensation and polyaddition), and to describe structure and properties of selected intermediates and final polymeric products. The focus is on five-membered ring cyclic carbonate intermediates, which were obtained by cycloaddition of carbon dioxide to selected glycidyl ethers and thiol-ene coupling of unsaturated cyclic carbonates...
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Isocyanate-Free Polyurethanes
PublicationIsocyanate-free polyurethanes (also called non-isocyanate polyurethanes, or NIPUs) are alternatives to the conventional (commercially used) polyurethanes synthesized using di- or polyisocyanates, polyols, and chain extenders with low molecular weight. The major routes of NIPUs’ synthesis involve polyaddition of cyclic carbonates and di- or polyamines, polycondensation of carbamates, and diols. The most important intermediates are...
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Non-Isocyanate-Based Waterborne Polyurethanes
PublicationNon-isocyanate polyurethanes (NIPUs) are a greener alternative for the conventional polyurethanes synthesized using toxic and moisture-sensitive di- or polyisocyanates. The most often described method of NIPU synthesis involves the reaction of five-membered cyclic carbonates with amines, and resulting polymers containing primary and secondary hydroxyl groups (so they are also known as polyhydroxyurethanes), which can be further...
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Parallel simulations of electrophysiological phenomena in myocardium on large 32 and 64-bit Linux clusters.
PublicationW pracy podjęto badania i przeprowadzono symulacje zjawisk elektrofizjologicznych w mięśniu sercowym z wykorzystaniem wytworzonego w tym celu oprogramowania równoległego opartego na MPI. Zaimplementowano i zbadano ulepszenia kodu prowadzące do uzyskania dobrej skalowalności oraz przeprowadzono testy wydajności na najnowszych 32 i 64-bitowych klastrach linuksowych. Praca stanowi próbę równoległej implementacji znanego podejścia...
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An efficient algorithm for the longest tandem scattered subsequence problem.
PublicationReferat dotyczy zagadnienia wyznaczania najdłuższego podciągu podwójnego (typu x1,x2,...,xk,x1,x2,...,xk) dla zadanego ciągu znaków (y1,y2,...,yn). Podano algorytm o złożoności obliczeniowej O(n^2) i pamięciowej O(n) znajdujący optymalne rozwiązanie postawionego problemu.
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Challenges and recent advances in bio-based isocyanate production.
PublicationPolyurethanes (PUs) are key players in the plastics industry. According to the Global Polyurethane Market (2019–2023), their value in the global market reached $95.13 billion in 2019 and is expected to grow at a compound annual growth rate of 12%. This is in line with the increase in the number of research papers and patents on the synthesis and application of petroleum-based PUs (P-PUs) and biomass or green PUs (G-PUs) (from 67 657...
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The LS-index: A Survey
PublicationNiniejszy przegląd jest oparty na wykładach autora wygłoszonych na NATO-ASI-SMS w 2004 roku na University of Montreal w Kanadzie.Niech H będzie przestrzenią Hilberta. Rozważmy pole wektorowe f zdefiniowane na H postaci f(x)=L(x)+K(x), gdzie L jest silnie nieokreślonym, ograniczonym operatorem liniowym, a K jego pełnociągłym zaburzeniem. W tej pracy prezentujemy rozszerzenie klasycznego indeksu Conley'a na potoki generowane przez...
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Indeks nazwisk [Index of persons]
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The Conley index and spectral sequences
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E-cohomological Conley index
PublicationIn this thesis we continue with developing the E-cohomological Conley index which was introduced by A.Abbondandolo. In particular, we generalize the index to non-gradient flows, we show that it an possesses additional multiplicative structure and we prove the continuation principle. Then, using continuation principle, we show how the computation of the E-cohomological Conley index can be reduced to the computation of the classical...
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Cross-linked epoxy-isocyanate blends containing Epidian-6 modified by glycols
PublicationPolymeric films of cross-linked structure may be formed using epoxy-isocyanate blends composed of Epidian-5 epoxy resin, 4,4’-diphenylmethanediisocyanate (MDI), Z-1 polyamine hardener and Epidian-6 epoxy resin modified by glycols. The effect of the component natures and ratio, process temperature and time on the gel-fraction content, as well as film hardness, was examined. The chemistry of the film forming process was determined...
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Numerical Modelling for Prediction of Compression Index from Soil Index Properties in Jimma town, Ethiopia
PublicationIn this study, correlations are developed to predict compression index (Cc) from index parameters so that one can be able to model Jimma soils with compression index using simple laboratory tests. Undisturbed and disturbed soil samples from twelve different locations in Jimma town were collected. Laboratory tests like specific gravity, grain size analysis, Atterberg limit, and one-dimensional consolidation test for a total of twenty-four...
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Recent advances in compatibilization strategies of wood-polymer composites by isocyanates
PublicationWood-polymer composites technologies are gaining more and more attention in the scientific community, positively affecting the increase in their industrial applications, for example, automotive, building, 3D printing, etc. Many research works are focused on the improvement in matrix–lignocellulosic filler interactions to produce highly filled composites with satisfying performance properties. In this field of research, using isocyanates...
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A mathematical model of rheological behavior of novel bio-based isocyanate-terminated polyurethane prepolymers
PublicationIn this paper, the results of rheological study on isocyanate-terminated polyurethane prepolymers, containing modified soybean oil residues incorporated into the chemical structure are described. Isocyanate-terminated prepolymers were synthesized from 4,4′-diphenylmethane diisocyanate and the mixture of hydroxylated soybean oil and commercial polyether. The measurements were performed by using rotary rheometer R/S-CPS+ (Brookfield,...
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Synthesis, structure and properties of novel poly(hydroxyurethane)s obtained by non-isocyanate route
PublicationNon-isocyanate polyurethanes (NIPUs) can be synthesized by polyaddition of five-membered bis(cyclic carbonate)s and primary diamines. NIPUs are an alternative for the commonly used (in the form of foams, elastomers, coatings or fibers) in the industry polyurethanes obtained using toxic and moisture sensitive diisocyanates, polyols and low-molecular weight chain extenders. The main aim of this work was to synthesize non-isocyanate...
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Fixed orbit index for equivariant maps
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The Conley index, cup-length and bifurcation
PublicationZastosowano strukturę modułu w indeksie kohomologicznym Conleya do dowodu twierdzenia o minimalnej ilości rozwiązań okresowych dla układów Hamiltonowskich. Wykazano też ogólne twierdzenia dotyczące nietrywialności struktury mudułu.
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Spectral splittings in the Conley index theory
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Conley type index and hamiltonian inclusions
PublicationOpisano definicję i własności indeksu dla zbiorów niezmienniczych wielowartościowego układu dynamicznego w nieskończenie-wymiarowej przestrzeni Hilberta. Podano nowe przykłady zastosowań do twierdzeń o istnieniu nietrywialnych rozwiązań okresowych układów hamiltonowskichz prawą stroną niegładką.
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Sources of Return in the Index Futures Markets
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The cohomological span of LS-Conley index
PublicationIn this paper we introduce a new homotopy invariant – the cohomological span of LS-Conley index. We prove the theorems on the existence of critical points for a class of strongly indefinite functionals with the gradient of the form Lx+K(x), where L is bounded linear and K is completely continuous. We give examples of Hamiltonian systems for which our methods give better results than the Morse inequalities. We also give a formula...
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The Maslov index and the spectral flow—revisited
PublicationWe give an elementary proof of a celebrated theorem of Cappell, Lee and Miller which relates the Maslov index of a pair of paths of Lagrangian subspaces to the spectral flow of an associated path of self-adjoint first-order operators. We particularly pay attention to the continuity of the latter path of operators, where we consider the gap-metric on the set of all closed operators on a Hilbert space. Finally, we obtain from Cappell,...
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Poly(urethaneamideimide)s from a cycloaliphatic diisocyanate
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On the Conley index in Hilbert spaces –- a multivalued case
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Morse inequalities via Conley index theory
PublicationThe relation known as the Morse inequalities can be extended to a more general setting of flows on a locally compact metric spaces (Conley index) as well as dynamical systems on Hilbert spaces (LS-index). This paper is a discourse around this extension. Except the part concerning the LS-index the material is self-contained and has a character of a survey.
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On the Conley index in Hilbert spaces - a multivalued case
PublicationW pracy podano definicję niezmiennika topologicznego wykrywającego zbiory niezmiennicze dla wielowartościowych układów dynamicznych generowanych przez inkluzje różniczkowe semiliniowe w przestrzeni Hilberta. Naszkicowano możliwość zastosowania do badania rozwiązań okresowych inkluzji hamiltonowskich.
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Conley type index applied to Hamiltonian inclusions
PublicationPodano dowód istnienia nietrywialnych rozwiązań okresowych dla inkluzji Hamiltonowskich, z potencjałem lokalnie Lipschitzowskim, okresowym, uogólniając klasyczne twierdzenie Ammana- Zehndera. Użyto techniki z teorii indeksu Conley'a dla wielowartościowych potoków w przestrzeni Hilberta.
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On splitting of the NICS(1) magnetic aromaticity index
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Opitmalising Human Development Index with sensitivity analysis
PublicationResearch background: Composite indicators are commonly used not only to measure economic development, the standard of livin g, competitiveness, fairness, effectiveness but are also willingly implemented in to many different fields. How- ever, it seems that in most cases the variable weig hting procedure is avoided or erroneous since in most cases so-called “wights by belief” are...
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On the Conley index in Hilbert spaces in the absence of uniqueness
PublicationW artykule podana jest konstrukcja indeksu Conley`a w przestrzeniach nieskończonego wymiaru dla równań różniczkowych bez jednoznaczności rozwiązań. Celem pracy jest przygotowanie właściwej teorii do badań ilościowych i jakościowych pewnych typów nieliniowych układów eliptycznych.
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Operation of diesel engines as the index of their reliability and safety
PublicationPrzedstawiono propozycję ilościowej interpretacji działania systemów technicznych która jest rozpatrywana jako wielkość fizyczna z jednostką miary zwaną dżulosekundą [dżulxsekunda]. Wykazane zostanie też, że taka interpretacja działania może być uznana za wskaźnik niezawodności, a w szczególnych przypadkach - wskaźnik bezpieczeństwa funkcjonowania takiego sytemu. Do uzasadnienia takiej przydatności wspomnianego działania silnika...
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Renewable natural resources as green alternative substrates to obtain bio-based non-isocyanate polyurethanes-review
PublicationCommercially available polyurethanes are synthesized by the polyaddition of diisocyanates with polyols and low molecular weight chain extenders. A new approach to polyurethanes synthesis is realized via non-isocyanate routes. Negative impacts of petroleum-based chemicals on the environment and human health as well as gradual reduction of fuel-based resources, which leads to an increase in their prices, are an incentive to looking...
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DETERMINATION OF THE HYDROXYL NUMBER OF GROUND TIRE RUBBER PARTICLES VIA MODIFIED TEST METHOD FOR ISOCYANATE GROUPS
PublicationNowadays, considering the environmental trends and law regulations associated with the circular economy, it is very important to seek for the methods of by-products and waste utilization. The example of such material, which requires the attention and recycling method is ground tire rubber generated during recycling of post-consumer car tires. It can be introduced into various polymer matrices as a filler, but to enhance its effectivity...
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Synthesis and structural characterization of bio-based bis(cyclic carbonate)s for the preparation of non-isocyanate polyurethanes
PublicationBio-based cyclic carbonates are of significant research interest as monomers for non-isocyanate polyurethane (NIPU) synthesis. This research describes the synthesis of a series of five-membered bis(cyclic carbonate)s using bio-based polyether polyols (PO3G) with different molecular weights (250, 650 and 1000 g mol−1) and carbon dioxide as green feedstocks. The utilization of CO2 as a source of carbon in the chemical reaction is...
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Index filtrations and Morse decompositions for discrete dynamical systems
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Fixed point index for $G$-equivariant multivalued maps
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On homotopy Conley index for multivalued flows in Hilbert spaces
PublicationPodano aproksymacyjną definicję indeksu homotopijnego, otrzymując naturalne związki z podobnymi niezmiennikami. Zbadano własności tego niezmiennika i zastosowano do badania gradientowych potoków wykazując pewne geometryczne własności zbiorów niezmienniczych
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Non-disjoint functional decomposition of index generation functions
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Linear and Non-linear Decomposition of Index Generation Functions
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The Conley Index and Rigorous Numerics for Attracting Periodic Orbits
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Relations between the domination parameters and the chromatic index of a graph
PublicationIn this paper we show bounds for the sum and the product of the domination parameters and the chromatic index of a graph. We alsopresent some families of graphs for which these bounds are achieved.
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Conley index in Hilbert spaces and the Leray-Schauder degree
PublicationZdefiniowane są liczby Bettiego i charakterystyka Eulera LS-indeksu dla potoków generowanych przez pole zwarte w przestrzeni Hilberta. Główna teza pracy to wzór typu Poincare-Hopfa łączący wspomnianą chatrakterystykę Eulera ze stopniem Leray-Schaudera.
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The circular chromatic index of some class 2 graphs
PublicationW artykule został wyznaczony cyrkularny indeks chromatyczny dla dwóch rodzin grafów klasy 2. Co więcej, podano nie trywialne oszacowania tego parametru dla snarków Isaacsa i Goldberga. Na koniec artykułu rozważana jest złożoność obliczeniowa problemów związanych z cyrkularnym kolorowaniem krawędzi.
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Quantitative interpretation of energy-based systems and index of their reliability
PublicationW artykule zaproponowano interpretację wartościującą działania, które rozumiane jest jako wielkość fizyczna o jednostce miary zwanej dżulosekundą. Przedstawiono oryginalną metodę analizy i oceny tak rozumianego działania dowolnego systemu energetycznego z uwzględnieniem jego niezawodności i bezpieczeństwa. Do uzasadnienia przydatności tak interpretowanego działania zastosowano jednorodny proces Poissona. Proces ten umożliwił skonstruowanie...
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Index filtrations and Morse decomposition for discrete dynamical systems
PublicationOn a Morse decomposition of an isolated invariant set of a homeomorphism(discrete dynamical system) there are partial orderings defined by the homeomorphism.These are called admissible orderings of the...
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Topological invariants for equivariant flows: Conley index and degree
PublicationAbout forty years have passed since Charles Conley defined the homotopy index. Thereby, he generalized the ideas that go back to the calculus of variations work of Marston Morse. Within this long time the Conley index has proved to be a valuable tool in nonlinear analysis and dynamical systems. A significant development of applied methods has been observed. Later, the index theory has evolved to cover such areas as discrete dynamical...
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Morse cohomology in a Hilbert space via the Conley index
PublicationThe main theorem of this paper states that Morse cohomology groups in a Hilbert space are isomorphic to the cohomological Conley index. It is also shown that calculating the cohomological Conley index does not require finite-dimensional approximations of the vector field. Further directions are discussed.