Academic literature on the topic 'RMN double quanta'

Antecedentes: Las resinas alquídicas altamente ramificadas,usualmente han sido obtenidas a partir de poliésteres polioles altamente ramificados (HBP) de segunda, tercera y cuarta generación. Objetivo: En este estudio se evaluó la influencia de la proporción de TOFA en las propiedades estructurales, térmicas, reológicas y de película de unas resinas alquídicas altamente ramificadas (NRA). Metodología: Para obtener las NRA, las respectivas cantidades de un HBP de primera generación (HBP1G), ácidos grasos de tall oil (TOFA) y de ácido p-toluensulfónico (0.1 %), fueron llevadas al reactor. La temperatura fue mantenida a 200°C. El sistema se mantuvo bajo agitación mecánica (200 rpm) y la conversión de la reacción fue evaluada por mediciones de valor ácido (VA). Las relaciones molares de HBP1G: TOFA, fueron las siguientes: 1:3 (NRA1), 1:4 (NRA2), 1:5 (NRA3) y 1:6 (NRA4). Resultados: El VA de las NRA fue inferior al de TOFA, el valor hidroxilo (VOH) fue inferior al del HBP1G. Esto indica que se llevó a cabo la reacción de esterificación entre TOFA y el HBP1G. La conversión de la reacción para obtener las NRA fue superior al 90 %. Por análisis de resonancia magnética nuclear (RMN) fue evidenciada la señal de los protones metilenos unidos a grupos OH del HBP1G y disminuyó su intensidad en la NRA1, debido a la reacción entre el HBP1G y TOFA. Las dimensiones hidrodinámicas de las NRA1, NRA2 y NRA3 fueron nanométricas. Las propiedades de película fueron buenas. Conclusión: Las NRA presentaron baja viscosidad. Además, todas exhibieron grupos OH y dobles enlaces, los cuales permite que estos materiales sean empleados para obtener materiales híbridos y como agentes entrecruzantes. Las NRA presentaron buenas propiedades de película.Palabras clave: Ácidos grasos de tall oil, poliéster poliol altamente ramificado, propiedades, resinas alquídicas. AbstractBackground: Hyperbranched alkyd resins have usually been obtained from hyperbranched polyester polyols (HBP) of second, third and fourth generations. Objectives: In this work the influence of the proportion of TOFA on the structural, thermal, and rheological and films properties of hyperbranched alkyd resins (NRA) were evaluated. Methodology: In order to obtain the NRA, the respective amount of HBP of fifth generation (HBP1G), tall oil fatty acids (TOFA) and p-toluenesulphonic acid (0.1wt%), were taken to the reactor. The temperature was kept at 200 °C. The system was kept under mechanical stirring (200 rpm) and the conversion of the reaction was evaluated by measurement of acid value (VA). The molar ratios of HBP:TOFA were as follows; 1:3 (NRA1), 1:4 (NRA2), 1:5 (NRA3) y 1:6 (NRA4). Results: VA of the NRA was lower than that of TOFA, the hydroxyl value (VOH) was minor compared to that of HBP1G. This is an indication that the esterification reaction between TOFA and HBP1G was carried out. The reaction conversion for obtaining the conversion to NRA was higher than 90 %. By nuclear magnetic resonance (NMR) analysis, the signals of the methylene protons joined to OH groups of the HBP1G were evidenced and decreased in their intensity in the NRA1, due to the reaction between HBP1G and TOFA. The hydrodynamic dimensions of the NRA1, NRA2 and NRA3 were nanometrics. Conclusions: The NRA presented the lowest viscosity. Furthermore all NRA, exhibited OH groups and double bonds, which allow that these materials be employed for obtaining hybrid materials and also as crosslinking agents. The NRA showed good film properties.Keywords: tall oil fatty acids, hyperbranched polyester polyol, properties, alkyd resins. ResumoAntecedentes: (foram obtidas) As resinas alquídicas altamente ramificadas foram usualmente obtidas (construção inglesa) de poliésteres poliol altamente ramificados (HBP) de segunda, terceira e quarta geração. Objetivo: Neste estudo foi avaliada a influência da proporção de TOFA nas propriedades estruturais, térmicas, reológicas e de filmes de resinas alquídicas altamente ramificadas (ARN). Metodologia: Para obter a ARN, as quantidades respectivas de uma primeira gera�o de HBP (HBP1G), �idos gordos de tall oil (TOFA) e �ido p-toluenossulf�ico (0,1%) foram levadas para o reactor. A temperatura foi mantida a 200 ° C. O sistema foi mantido sob agitação mecânica (200 rpm) e a conversão da reação foi avaliada por medidas do valor ácido (VA). As proporções molares de HBP1G: TOFA foram as seguintes: 1: 3 (NRA1), 1: 4 (NRA2), 1: 5 (NRA3) e 1: 6 (NRA4). Resultados: VA ARN TOFA foi menor do que o valor de hidroxilo (OHV) foi menor do que HBP1G.Esto indica que realizada a reaco de esterificao entre o TOFA e HBP1G. A conversão da reação para obter a ARN foi maior que 90%. Por análise de ressonância magnética nuclear (RMN), evidenciou-se o sinal dos prótons de metileno ligados aos grupos OH de HBP1Gy e sua intensidade diminuiu em NRA1, devido à reação entre HBP1G e TOFA. As dimensões hidrodinâmicas do NRA1, NRA2 e NRA3 foram nanométricas. As propriedades do filme eram boas. Conclusão: A NRA apresentou baixa viscosidade. Além disso, todos exibiram grupos OH e ligações duplas, o que permite que estes materiais sejam utilizados para obter materiais híbridos e como agentes de reticulação. As NRAs mostraram boas propriedades de filme.Palavras-chave: Ácidos grasos de tall oil, poliéster poliol altamente ramificado, propiedades, resinas alquídicas.

Les thermoplastiques vulcanisés (TPV) sont des mélanges de polymères présentant à la fois des propriétés d'élasticité et de mise en œuvre et en forme. L'objectif de cette thèse est d'étudier les TPV à base d’un système PP/EPDM malgré la complexité de leurs formulations et de comprendre les mécanismes gouvernant la propriété de recouvrance élastique. La première partie de ce travail s'est concentrée sur l'influence de la chimie de réticulation sur les mécanismes de relaxation aux temps longs des réseaux élastomères réticulés. Il a été constaté que la réticulation radicalaire à partir de la décomposition thermique d’un peroxyde menait à une meilleure recouvrance élastique qu’avec la réticulation avec une résine phénolique. Cependant, la chimie de la réticulation n'est pas le paramètre de premier ordre qui influence cette propriété en ce qui concerne les TPV. En effet, elle dépend surtout de la formulation et du ratio thermoplastique/élastomère, ainsi, leurs influences sur les morphologies finales et sur la déformation rémanente en compression ont été étudiées dans une seconde partie. De plus, l'influence des charges inorganiques a également été étudiée dans les systèmes élastomères avec l'ajout de noir de carbone ou de silice ou dans les systèmes TPV avec l'ajout de noir de carbone. Il a été démontré que l'ajout de noir de carbone dans les systèmes réticulés au peroxyde est bénéfique et améliore les propriétés mécaniques : déformation rémanente après compression et comportement en traction (module d’Young, allongement à la rupture). En effet, la densité de réticulation et la compatibilité entre les polymères ont été améliorées. Enfin, une méthode RMN à bas champ a été utilisée pour l’étude de ces systèmes, notamment avec l'utilisation de la séquence Double Quanta (DQ) qui donne accès aux variations des mobilités moléculaires dans les matériaux avec la mesure du couplage dipolaire résiduel
Thermoplastics vulcanizates (TPVs) are polymer blends with interesting elasticity and processability properties. The objective of this thesis was to study PP/EPDM TPV despite the complexity of their formulations and to understand what influences the elastic recovery property. The first part of this work was focused on the influence of crosslinking chemistry and its statistics on the long-time relaxation mechanisms of crosslinked elastomeric networks. It was found that radical peroxide crosslinking provides better recovery elasticity than phenolic resin one. However, crosslinking chemistry has been seen to not be the first-order parameter that influences this property for TPV. It depends mostly on the formulation and the thermoplastic/elastomer ratio, their influence on the final morphology and compression set have been then studied in a second part. Moreover, the influence of inorganic fillers was also studied in elastomeric systems with the addition of CB or silica or in TPV systems with the addition of CB. It has been seen that the addition of CB in a system crosslinked with peroxides is beneficial for the improvement in mechanical properties: compression set or tensile test. Indeed, the crosslinking density and the compatibility between polymers were improved. Finally, a low-field NMR method has been applied to these systems, in particular with the use of the Double Quanta (DQ) sequence which gives access to the variations of molecular mobilities in the materials with the measurement of a residual dipolar coupling

Esta tese baseia-se no estudo da dinâmica e conformação de polímeros no estado sólido utilizando-se técnicas modernas de RMN. Para o estudo quantitativo da dinâmica molecular lenta dos grupos laterais em uma série de poli (alqui1 metacrilato)s que apresentam diferentes tamanhos para os seus grupos laterais foram utilizadas duas novas técnicas de exchange: centerband-only detection of exchange (CODEX) e pure exchange (PUREX). Rotações dos grupos ésteres de 180° flip) acopladas a movimentos de pequenos ângulos em torno da cadeia principal (< 20°), que são associados a relaxação β nestes polímeros, são observados distintamente. As porcentagens de grupos laterais que realizam os movimentos de flip foram obtidas com 3% de precisão. Esses valores decrescem com o tamanho do grupo lateral, indo de 34% (PMMA) até cerca de 10% (PcHMA) à temperatura ambiente. No PMAA nenhum movimento lento dos grupos laterais é detectado. A fração de grupos laterais que realizam o flip se mantém constante com o aumento da temperatura para o PMMA até próximo da sua transição vítrea (Tg), enquanto que para o PEMA, o PiBMA e o PcHMA essa fração aumenta continuamente até próximo da Tg (de 31% para 80% para o PEMA). Movimentos independentes de pequena amplitude (< 5°) que cooperam para a acomodação dos grupos laterais durante o flip das cadeias vizinhas também foram verificados. O monitoramento do sinal atribuído ao grupo CH2 através da técnica CODEX confirma os resultados obtidos para o movimento da cadeia principal. Além disso, observa-se em alguns poli(acri1atos α-substituídos) que o tamanho dos grupos laterais a também têm influência na fração dos grupos ésteres que sofrem reorientação a 25°C . Para o estudo da conformação de polímeros foram implementados experimentos Double Quantum, que determinam ângulos de torção entre pares 13C-13C na cadeia polimérica. Foram realizados experimentos para dois polímeros, poli(óxido etileno) - (POE) e poli(eti1eno teraftalato) - (PET), enriquecidos em 13C com e sem desacoplamento homonuclear (13C-13C) em um espectrômetro Variam Inova 400.
This work is based on the study of dynamics and conformation of solid-state polymers, using NMR modern techniques. For the quantitative study of slow sidegroup dynamics in a series of poly(alkyl methacrylate)s and other of poly(α-substituted acrylate)s with varying sidegroup sizes two new 13C exchange techniques were used: centerband-only detection of exchange (CODEX) and pure exchange (PUREX). Flips and small-angle motions of the ester groups associated with the p-relaxation are observed distinctly, and the fraction of slowly flipping groups has been measured with 3% precision. A decreasing in these values occurs growing the sidegroup size. In PMMA, 34% of sidegroups flip, while the fraction is c.a. 10% in PcHMA around room temperature. In PMAA, no slow sidegroup flips are detected. In PMMA, the flipping fraction is temperature-independent between 25°C and 96°C, while in PEMA, PiBMA, and PcHMA it increases continuously between room temperature and Tg (from 31 to 80% for PEMA). Backbone CH2 CODEX data confirm the results obtained for the main chain movements. Flip-independent small amplitude motions (< 5°) are also observed. Besides, it is noticed that in some poly(α -substituted acrylate)s the a sidegroup size has influence in the fraction of slowly flipping ester groups at 25°C. For the study of polymers conformation Double Quantum NMR experiments were used, for torsion angles determination between 13C-13C pairs through the polymer chain. Experiments for two standards 13C labeled samples: poly(ethy1ene oxide) - (PEO) and poly(ethy1ene teraftalate) - (PET) were performed, with and without homonuclear decoupling (13C-13C), in a Varian Inova 400 spectrometer.

Abstract The Doubled-Semion model is another simple example of generalizing the toric code. Here we start with a planar diagram algebra that is the d=-1, Z2 loop gas. I.e, here a loop is given the value of -1. This is also known as the nontrivial cocyle of Z2. This model can be thought of as the simplest case of a twisted Kitaev Quantum Double, and it is also the simplest example of the Drinfeld double of a modular anyon theory (the double of the semion theory). In this case we construct a Hamiltonian such again we have a loop gas, but now flipping over a plaqutte incurs a sign in the wavefunction if we change the parity of the number of loops. We again turn to the tube algebra to identify the excitations of the model, which are both right- and left-handed semions. We run into a problem related to the nontrivial Frobenius-Schur indicator of the input diagram algebra. However, here we can resolve the issue by choosing a convenient gauge.

To achieve reliable system intelligence outstanding results, current computational system modeling and simulation community has to face and to solve two orders of modeling limitations at least. As a solution, the author proposes an exponential, pre-spatial arithmetic scheme (“all-powerful scheme”) by computational information conservation theory (CICT) to overcome the Information Double-Bind (IDB) problem and to thrive on both deterministic noise (DN) and random noise (RN) to develop powerful cognitive computational framework for deep learning, towards deep thinking applications. In a previous paper the author showed and discussed how this new CICT framework can help us to develop even competitive advanced quantum cognitive computational systems. An operative example is presented. This paper is a relevant contribution towards an effective and convenient “Science 2.0” universal computational framework to develop deeper learning and deep thinking system and application at your fingertips and beyond.

Of all the lasers in use today, it is only the semiconductor laser where the quantum noise, inevitable in all lasers, is of major practical concern. This is due to two reasons. The first one is that since semiconductor lasers have a very small physical volume, the cavity quality factor is very small, which results, according the the Schalow-Townes formula, in a large spectral width of the laser output. The second reason is that due to the widespread application of semiconductor lasers in real-life optical fiber comunications systems, the noise aspects are of real concern. The basic physical mechanism of this noise is the addition of spontaneous emission power to the laser field. This effect is compounded and amplified by coupling between intensity and phase fluctuations, which are characteristic of semiconductor lasers. In the talk we will review those physical effects and show some possible ways of reducing the laser linewidth. These ways include the use of large external cavity and/or coupling of frequency dependent loss mechanism into the laser oscillators. The effect of spontaneous emission is also a limiting factor in optical fiber amplifier systems, which are assuming major practical importance. In this case the major noise mechanism is beating between the signal propagating in the fiber and the background amplified spontaneous emission power. The basic limitation on signal to noise ratio in a practical system because of this mechanism will be reviewed. Experiments performed in various laboratories will be discussed and compared to the theory. A limiting noise behavior of the optical amplifier fiber system is shown to consist of a transmission system with uniformly distributed gain along the whole length of the fiber. The penalty factors for using other schemes of optical fiber amplification compared to the ideal system will be discussed. The last mechanism to be discussed will be that of double Rayleigh scattering in fibers. This converts phase noise to intensity noise. The resulting limiting RIN will be discussed and compared with new experiments.