Simultaneous measurement of viscoelastic changes and cell opening during processing of flexible polyurethane foam

Neff, Raymond; Macosko, Christopher W.

doi:10.1007/bf00396514

Cited by 41 publications

(49 citation statements)

References 25 publications

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“…As reported by Singh and Bhattacharya (2005), the phenomenon of opening of the gas cells is directly associated with release of gas from the cells, which leads to reduction of pressure. Similar results were reported for reacting polyurethane foams, where the cell opening was detected by a sudden drop in normal force (Neff and Macosko 1996).…”

Section: Changes In Dough Pressuresupporting

confidence: 88%

Identification of Baking Expansion Phases of Leavened Dough Using an Experimental Approach

Miś

Nawrocka

Dziki³

2016

Food Bioprocess Technol

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A measurement system was designed to study changes in the volume, pressure, and viscosity of dough leavened by baking powder during model baking. Analysis of the volume changes demonstrated two baking stages, i.e. dough expansion and crumb shrinking. Through the analysis of pressure and viscosity extremes, the expansion stage was divided into five phases: stress relaxation (R) characterised by a mild pressure decline; gluten matrix softening (S), during which the decrease in viscosity is accompanied by a gradual pressure rise contributing to substantial dough expansion (by ∼54 %); starch gelatinisation and protein aggregation (G) characterised by rapidly increasing viscosity; gas bubble opening (O) reflecting a rapid pressure reduction; and boiling of water in dough (B), which ends at initiation of crumb shrinking. The study showed that enrichment of the dough with carob fibre increased the contribution of phases S and O to dough expansion at the cost of phase G. A similar contribution of the expansion phases was reported for the Bombona cultivar, which exhibits the highest gluten content. In contrast, the Finezja and Katoda cultivars, which have a lower gluten level, were characterised by an approximately two-fold higher impact of phase G on the increase in dough expansion. The results indicated that the developed method for identification of baking expansion phases of leavened dough can be useful in baking characteristics of raw materials and bakery additives.

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Section: Changes In Dough Pressuresupporting

confidence: 88%

Identification of Baking Expansion Phases of Leavened Dough Using an Experimental Approach

Miś

Nawrocka

Dziki³

2016

Food Bioprocess Technol

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“…to form a stable cellular structure, but not so fast as to stop bubble growth. [27] This process has been described by in-situ studies [12,50,51], establishing four stages during polyurethane foaming (Figure 2.6).…”

Section: Foaming Processmentioning

confidence: 92%

“…Therefore, the function of a shield is to prevent the emissions of the electric and magnetic waves from propagation from one region to another by using conducting or magnetic materials. [257,258] The EMI shielding effectiveness (SE) of FPU nanocomposite foams is directly related to their conductivity in the X-band frequency region (8)(9)(10)(11)(12) and defined as: (4.24) where Pin is the incident power and Pout is the power transmitted through a shielding material. In order to compare the different systems, the specific EMI shielding effectiveness that is, the EMI SE corrected by the density of the material is plotted for FPU-25% HS and FPU-32.5% HS nanocomposite foams (Figure 4.32).…”

Section: Electromagnetic Interference (Emi) Shieldingmentioning

confidence: 99%

“…The blowing reaction, produced between the isocyanate and water, forms urea hard segments (HS) and carbon dioxide gas. [12] A segmented block copoly(urethane-urea) is then the result of these two reactions, where the urea hard segment groups are covalently bonded to the polyol soft segments (SS) through urethane linkages. The phase-separated morphology of PU foams and the ratio of HS/SS have a profound effect on the final properties of the system.…”

Section: Introductionmentioning

confidence: 99%

“…La reacción de espumado, se produce entre el isocianato y el agua, formando segmentos duros de urea y dióxido de carbono. [12] Como resultado de estas reacciones se forma un copolímero de bloque segmentado uretano-urea, donde los segmentos duros de urea están covalentemente unidos a los segmentos blandos de poliol mediante enlaces uretano. La morfología de fases separadas de las espumas de PU y la relación entre segmentos duros y blandos tienen un efecto significativo en las propiedades finales del sistema.…”

Section: Introductionunclassified

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Estudio de Nanocompuestos de Espumas de Poliuretano Reforzadas con Nanocargas en Base Carbono

Bernal¹,

Mar²

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A la meua familia AGRADECIMIENTOSQuisiera agradecer, en primer lugar, al Ministerio de Ciencia e Investigación por la financiación para la realización de esta Tesis, mediante la concesión de la Beca FPI.A mis directores de Tesis, Dra. Raquel Verdejo y Dr. Miguel Ángel López Manchado por darme la oportunidad de trabajar con vosotros. A Raquel, por todo lo que me has enseñado durante estos años y por todo el tiempo que me has dedicado. A Miguel Ángel por tus comentarios constructivos, tus consejos y tu paciencia.A mi tutor en la UPV, Prof. Vicente Amigò por toda la ayuda que me has brindado sin apenas conocerme.Al Prof. Miguel Ángel Rodríguez Pérez de la Universidad de Valladolid por darme la posibilidad de trabajar en tu grupo y aprender más sobre espumas.I would like to thank Prof. Anthony J. Ryan, from The University of Sheffield, and Prof. Isabelle Huynen, from Université Catholique de Louvain, for your support and interest on my work.A todos mis compañeros del grupo por todos los ánimos y las risas. A Mario, Lean, Laura Peponi, Nicoletta, Iván y Sami. A mis chicas, Nella, Nat y Lauris, por todos los buenos momentos juntas entre recetas de cocina, clases de punto y bailes Bollywood! Quiero agradecer especialmente a Nella por ser mi profesora de la vida durante estos años y por las largas tardes-noches compartidas en la oficina. Y a Mario, nuestro "chico guapo" por todo el apoyo y por esas "características limitantes" que nos unen.A todo el grupo de Cauchos, en especial a Juan, Irene, Marta y Pilar, por ser como sois y por todas esas celebraciones en el laboratorio con vino, callos, migas y pasteles. Y a Miguel Arroyo, por esas paellas "madrileñas" que me hacen sentir como en casa.A Rodri, Jose e Isabel Quijada por haberme dejado participar en vuestros trabajos, por todo lo que he aprendido con vosotros y por haber confiado en mí.Al grupo del CellMat de la Universidad de Valladolid por haberme acogido tan bien durante las semanas que he estado con vosotros. En especial a Samu, Sergio y a Eusebio por vuestra colaboración en mis experimentos de radioscopia y DMA.I would like to thank my dear friends Masa, AC and Susi, for our great times in Sheffield.A special thanks to Isabel and Margherita for taking care of me during those hard months in Louvain-la-Neuve and for your friendship. Grazie Margheri per le nostre pause caffè e tutti gli scherzi! A todos mis amigos que me habéis apoyado durante este tiempo y, aunque en "la terreta" siempre os he tenido cerca. Y gracias a todas las personas que me han ayudado durante estos años. RESUMENLas espumas de nanocompuestos poliméricos tienen un gran interés tanto en áreas tecnológicas como científicas. Esto es debido a la combinación de las excelentes propiedades de las nanopartículas y la tecnología de espumado, dando lugar al desarrollo de materiales ligeros y multifuncionales. Este tipo de sistemas se utilizan en aplicaciones de alto rendimiento tan diversas como biomedicina, electrónica, paneles estructurales y embalajes, entre otras.Esta Tesis está basada en el desarro...

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Modeling the dynamics of reactive foaming and film thinning in polyurethane foams

Harikrishnan

Khakhar

2009

AIChE Journal

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Flexible polyurethane foams are widely used in cushioning and packaging applications. A model for the dynamics of formation of polyurethane foams is presented, which includes thinning of foam lamellae. Experimental measurements for water blown flexible foam formulations at different water concentrations are presented to validate the model. Adiabatic temperature rise measurements during foaming are used to obtain the kinetic parameters of the reactions of isocyanate with polyol and water. The variation of foam density during foaming is studied by weight loss and video shooting methods and both are compared to estimate the amount of blowing gas lost during foaming.

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Simultaneous measurement of viscoelastic changes and cell opening during processing of flexible polyurethane foam

Cited by 41 publications

References 25 publications

Identification of Baking Expansion Phases of Leavened Dough Using an Experimental Approach

Identification of Baking Expansion Phases of Leavened Dough Using an Experimental Approach

Estudio de Nanocompuestos de Espumas de Poliuretano Reforzadas con Nanocargas en Base Carbono

Modeling the dynamics of reactive foaming and film thinning in polyurethane foams

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