The Effect of Various Pigments and Binders on Coated Gloss, Print Gloss, and Delta Gloss

The objective of this thesis is to determine the effects that various pigments and binders have on the coated gloss, print gloss, and delta gloss values. The effects of coat weight and calendering on the glossing response of the sheet will also be determined. Supplemental tests such as Parker Print Surf Roughness, brightness, and opacity will be measured to further evaluate the coating formulations. A total eight different coating formulations were made using four very common pigments and two latex binders. The four pigments used were #2 clay (100%), calcined clay (15% substitution), delaminated clay (25% substitution), and calcium carbonate (100%). The two latex binders used were styrene butadiene (SBR) and polyvinyl acetate (PVAC). Latex binders were chosen because their gloss response when applied in coatings is better than starch or protein binders. In order to isolate the effect of the pigment and binders a number of variables were held constant or within the same range. The solids levels of all coatings was adjusted to 62%. The binder ratio used was 12% based on dry parts pigment. The Brookfield viscosity was adjusted within the same range using polyacrylate. The printing ink and the print conditions were held constant also. The ink used was a low viscosity water based flexographic ink. A low gloss ink was chosen in order to eliminate the effects of the ink on the print gloss. When pigments are used alone in coating formulations, their particle size has the most dramatic effect on the gloss response of the sheet. The finer particles create a more optically smooth sheet therefore giving higher gloss values. When binders are introduced into the sheet, the pigment to binder particle interaction also plays a major role. A coat weight increase of 5 g/m^2 gave an average increase in coated gloss of 10% and gave a 20% increase in calendered gloss. The delaminated clay using the PVAC as the binder showed the highest gloss response due to an increase in coat weight. Calendering the sheet improved all gloss values. The effect was greater for coated gloss than for the print gloss. This was desired because it proves that the gloss of ink did not contribute to the print gloss but that it was the coating structure that affected the gloss response. The effect of pigment and binder type varied depending upon the combination used. The calcined clay gave the highest calendered gloss values which was not expected. However, when these samples were printed they displayed the highest delta gloss. This is due to the large particle size of the calcined clay. High delta gloss values are not desired because they produce a contrast between the image of the coating and the printed image. The pigment-binder interaction played a major role in determining the gloss response. When the PVAC binder was used, the delaminated clay gave the best gloss response with a delta gloss value of near zero (.2). When the SBR was used, the #2 clay gave the best response in gloss response. This was expected because the SBR latex is known for its high gloss response. A more detailed description and interpretation of the results can be found in the results and discussion section

Simulation and assimilation of satellite altimeter data at the oceanic mesoscale

An improved "objective analysis' technique is used along with an altimeter signal statistical model, an altimeter noise statistical model, an orbital model, and synoptic surface current maps in the POLYMODE-SDE area, to evaluate the performance of various observational strategies in catching the mesoscale variability at mid-latitudes. In particular, simulated repetitive nominal orbits of ERS-1, TOPEX, and SPOT/POSEIDON are examined. Results show the critical importance of existence of a subcycle, scanning in either direction. Moreover, long repeat cycles ( 20 days) and short cross-track distances ( 300 km) seem preferable, since they match mesoscale statistics. Another goal of the study is to prepare and discuss sea-surface height (SSH) assimilation in quasigeostrophic models. Restored SSH maps are shown to meet that purpose, if an efficient extrapolation method or deep in-situ data (floats) are used on the vertical to start and update the model

Avaliação da resistência de união à microtração da resina composta pré-aquecida na cimentação de onlays de diferentes espessuras

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências da Saúde. Odontologia.A cimentação é considerada o procedimento mais crítico das restaurações indiretas e o cimento utilizado é considerado o elo mais fraco da estrutura formada pela associação peça protética-cimento-dente. O objetivo deste trabalho foi avaliar a resistência de união a microtração promovida pela resina composta pré-aquecida, utilizada para cimentação de restaurações indiretas de diferentes espessuras. Foram selecionados 32 incisivos bovinos hígidos padronizados com 12mm de comprimento e com a exposição da dentina coronária. Os dentes foram divididos em 4 grupos (n=8), de acordo com a espessura do bloco de resina composta e o cimento utilizado: grupos 1 e 2 (RC2, RC4) – blocos de resina composta de 2mm e 4mm de espessura e cimentação com resina composta pré-aquecida; grupos 3 e 4 (CR2, CR4) – blocos de resina composta de 2mm e 4mm e cimentação com cimento resinoso dual. Previamente a cimentação, os blocos foram jateados com óxido de alumínio, condicionados com ácido fosfórico a 37% e o sistema adesivo foi aplicado sem fotoativação. Os dentes bovinos foram jateados, condicionados e tiveram o adesivo fotoativado por 40s. A cimentação foi realizada com resina composta pré-aquecida para os grupos 1 e 2, e cimento resinoso dual para os grupos 3 e 4, com o auxílio de uma barreira de silicone, afim de permitir que a luz do fotopolimerizador haja somente na superfície oclusal do bloco. Os espécimes ficaram em um ambiente úmido e escuro durante 30 dias para aguardar a polimerização total do material para cimentação. Após 30 dias, os espécimes foram seccionados para obtenção de palitos de 1mm2, que foram submetidos ao teste de microtração. Os resultados mostraram que não houve diferenças estatísticas entre a resistência de união à microtração nos grupos RC2 e RC4 (p>0,05), bem como entre os grupos CR2 e CR4 (p>0,05). Entretanto, houve diferenças estatisticamente significativas entre CR2 e RC4 (p<0,05). Concluiu-se que a resina composta pré-aquecida como agente cimentante é tão efetiva quanto o cimento resinoso independente da espessura da restauração indireta utilizada (até 4 mm)

A compressible two-layer model for transient gas–liquid flows in pipes

International audienceThis work is dedicated to the modeling of gas-liquid flows in pipes. As a first step, a new two-layer model is proposed to deal with the stratified regime. The starting point is the isentropic Euler set of equations for each phase where the classical hydrostatic assumption is made for the liquid. The main difference with the models issued from the classical literature is that the liquid as well as the gas is assumed compressible. In that framework, an averaging process results in a five-equation system where the hydrostatic constraint has been used to define the interfacial pressure. Closure laws for the interfacial velocity and source terms such as mass and momentum transfer are provided following an entropy inequality. The resulting model is hyperbolic with non-conservative terms. Therefore, regarding the homogeneous part of the system, the definition and uniqueness of jump conditions is studied carefully and acquired. The nature of characteristic fields and the corresponding Riemann invariants are also detailed. Thus, one may build analytical solutions for the Riemann problem. In addition, positivity is obtained for heights and densities. The overall derivation deals with gas-liquid flows through rectangular channels, circular pipes with variable cross section and includes vapor-liquid flows

Technological solutions to reduce the geometrical defects during the cast film process

International audienceThe polymer cast film process induces some geometrical defects : the width reduction (neck-in defect) and the inhomogeneous decrease of the thickness distribution (edge bead defect). These defects prevent from predicting the film final dimensions and thus from a high industrial productivity. In this paper, a numerical model developed by the authors is used to test and optimize two technological solutions, aimed at reducing the geometrical defects : a localized air cooling on the edges of the film at the die exit and an "encapsulation die" which enables the extrusion of a high melt strength polymer along the outer edge of a core polymer. Numerical results are confronted with experimental investigation

Competition between Traveling Fluid Waves of Left and Right Spiral Vortices and Their Different Amplitude Combinations

Stability, bifurcation properties, and the spatiotemporal behavior of different nonlinear combination structures of spiral vortices in the counter rotating Taylor-Couette system are investigated by full numerical simulations and by coupled amplitude equation approximations. Stable cross-spiral structures with continuously varying content of left and right spiral modes are found. They provide a stability transferring connection between the initially stable, axially counter propagating wave states of pure spirals and the axially standing waves of so-called ribbons that become stable slightly further away from onset of vortex flow.Comment: 4 pages, 5 figure

An Overview of Molten Polymer Drawing Instabilities

International audienceDrawing instabilities and rupture are a serious limitation in polymer fibre and film processing. Draw resonance and fibre or film rupture depend on the processing conditions, heat transfer and on the rheology of the polymer and some of these defects may also be encountered for Newtonian fluids. This paper reviews the different instabilities observed in fibre spinning, cast-film and film blowing. The time dependent equations are presented for the simplified situation of constant width cast-film and two modelling strategies, linear stability analysis and direct simulation, are proposed and then applied to the different fibre and film processes. Read More: http://www.hanser-elibrary.com/doi/abs/10.3139/217.283

Etude expérimentale du défaut hélicoïdal d'un polystyrène en écoulement

National audienceL'objet de cet article est la caractérisation expérimentale de l'instabilité hélicoïdale observée lors de l'écoulement d'un polystyrène en géométrie axisymétrique. C'est en effet en rhéométrie capillaire que l'étude du défaut s'avère la plus simple : l'extrudat présente, au delà d'un certain débit, des distorsions hélicoïdales très nettes. L'étude présentée s'attache à décrire l'influence des conditions d'écoulement (géométrie, température...) sur le déclenchement de cette instabilité. Par ailleurs, une quantification du défaut en terme de périodicité révèle que la fréquence caractéristique de l'instabilité repose sur les propriétés viscoélastiques du polymère utilisé. Il semblerait, en outre, que l'initiation du défaut hélicoïdal soit liée au caractère élongationnel de l'écoulement dans le convergent