Melt rheology of tin phosphate glasses

Tags: phosphate glass, organic-inorganic, Beall GH, zinc phosphate, Applied Rheology, viscosity, U.S. National Science Foundation, JU, polyphosphate, Adalja SB, Quinn CJ, Otaigbe JU, Beall BH, Fundamentals of Inorganic Glasses, Encyclopedia of Polymer Science and Technology, University of Massachusetts, Amherst, Iowa State University, Pruski M, Iowa State University of Science and Technology Ames, Iowa, Chemical Engineering, temps de relaxation, Joshua U. Otaigbe, Arrhenius equation, Schmelzprozessieren von Glas, inorganic glasses, Tischendorf, Materials Science and Engineering, viscoelastic behavior, silicate glasses, Baumgaertel M
Content: Melt Rheology of Tin Phosphate Glasses
Sunil B. Adalja 1 and Joshua U. Otaigbe 1, 2* 1 Dept. of Materials Science and engineering 2 Dept. of Chemical engineering Iowa State University of science and technology Ames, Iowa 50011, USA *Email: [email protected] Fax: x1.515.294.5444 Received: 22.9.2000, Final version: 26.10.2000 Abstract: The melt rheology of a low Tg tin phosphate glass [Pglass] has been studied with oscillatory shear flow experiments to accelerate efforts to melt process the glass with different organic polymers. The w dependence of the complex viscosity h* of the Pglass is easily predicted by a modified Rouse model with two relaxation times. The complex viscosity of the glass at different temperatures and frequencies can be superposed and described by the Arrhenius equation. At higher temperatures, the melt viscosity of the Pglass increased monotonically with time. This viscosity rise is thought to be due to sample crystallization. The Pglass was melt-mixed with two different thermoplastic polymers (low-density polyethylene and polystyrene) to produce unique hybrid materials with interesting microstructures. Zusammenfassung: Die Schmelzrheologie eines niedrig-Tg Zinnphosphatglases wurde mittels oszillatorischen Scherstrmungsexperimenten untersucht, um die Anstrengungen zum Schmelzprozessieren von Glas mit verschiedenen organischen Polymeren zu beschleunigen. Die Frequenzabhдngigkeit der komplexen Viskositдt h* des Zinnphosphatglases kann leicht anhand eines modifizierten Rousemodells mit zwei Relaxationszeiten vorausgesagt werden. Die komplexe Viskositдt des Glases bei verschiedenen Temperaturen und Frequenzen kann ьberlagert und durch eine Arrhenius- Gleichung beschrieben werden. Bei hцheren Temperaturen steigt die Viskositдt der Schmelze aus Zinnphosphatglas monoton mit der Zeit an. Dieser Anstieg der Viskositдt ist vermutlich auf Kristallisation in der Probe zurьckzufьhren. Das Zinnphosphatglass wurde mit zwei verschiedenen, thermoplastischen Polymeren (LDPE und PS) schmelzvermischt um einzigartige Hybridmaterialien mit interessanten Mikrostrukturen herzustellen. Rйsumй: La rhйologie а l'etat fondu d'un verre de phosphate [verreP] de basse Tg a йtй йtudiйe au moyen d'expйriences d'йcoulement en cisaillement oscillatoire, afin d'accйlйrer les efforts entrepris pour mettre en oeuvre le fondu de verre aveC Diffйrents polymиres organiques. La dйpendance en frйquence de la viscositй complexe h* du verreP est aisйment prйdite par un modиle de Rouse modifiй avec deux temps de relaxation. La viscositй complexe du verre а diffйrentes tempйratures et frйquences peut кtre superposйe et est dйcrite par une йquation de type Arrhenius. A plus hautes tempйratures, la viscositй du fondu de verreP augmente avec Le Temps de maniиre monotone. Cette montйe en viscositй est attribuйe а la cristallisation de l'йchantillon. Le verreP a йtй mйlangй а l'йtat fondu avec deux polymиres thermoplastiques diffйrents (polyйthylиne basse densitй et polystyrиne) pour produire des matйriaux hybrides uniques possиdant des microstructures intйressantes.
Key words: Rheology, phosphate glasses, processing, modeling, organic-inorganic polymer hybrids, glass-polymer melt blends
1 INTRODUCTION Recent successes [1-9] in developing low-Tg inorganic glasses based on phosphate glass chemistry have spurred interest in THE RELATIONSHIP among processing, properties, and microstructure of organic-inorganic polymer hybrids. The low Tg [@ 100°C] of the inorganic glass phase permits it's loading at a very high content [up to 50 vol.% or 85 wt.%] in the hybrid. By contrast, such high glass loading levels are impossible to process by using conventional inorganic fillers
such as borosilicate [E-glass] glasses and conventional polymer processing method because of high intractable viscosity of the composite melt. Phosphate glasses [1-4, 7, 10-13] offer many advantages over the more traditional inorganic fillers such as silicate glasses [14]. One key advantage of the former is their Tg that is low enough to permit melt processing with engineering thermoplastics to afford composite hybrid systems
© Appl. Rheol. 11, 1, 10-18 (2001) This is an extract of the complete reprint-pdf, available at the Applied Rheology website http://www.appliedrheology.org 10 This is an exAtprapclitedofRthheeolcoogymplete reprint-pdf, available at the Applied Rheology website January/February 2h0t0tp1 ://www.appliedrheology.org
Fig. 9: SEM micrograph of the pure Pglass powder used in making the hybrids with organic polymers.
accounted for in the Palierne model and are expected to play a significant role in the viscoelastic behavior of the polymer-Pglass hybrid system. The Palierne model can be used to predict the linear viscoelastic behavior of polymer emulsions, taking into account the size of the viscoelastic droplets dispersed in a viscoelastic polymer matrix and the interfacial tension between the components. The model reduces to the Oldroyd model if the components are Newtonian liquids and the droplets are of a unique size [30]. CONCLUSION The melt rheology of a low Tg tin phosphate glass was studied and used to guide the selection of optimum processing temperatures with different thermoplastic polymers. The complex viscosity of the Pglass can be modeled by a modified Rouse model with two relaxation times. The frequency and temperature dependence of complex viscosity of the glass can be superposed and described by the Arrhenius- type relation. An Arrhenius flow activation energy of 87.08 kJ/mol was estimated for the Pglass. This value is consistent with the values reported for inorganic glass melts. The superpositioning of the experimental data enables the estimation of the viscosity for any frequency and temperature relevant to the processing of the Pglass. Thermal instabilities in the melt viscosity of the Pglass were observed at longer times, and these were accelerated at elevated temperatures. Special organic-inorganic hybrid materials were developed by melt-mixing the Pglass with LDPE and PS to yield materials showing evolution of a unique and interesting microstructure of the Pglass phase in the organic-inorganic polymer hybrids.These microstructures maybe beneficially exploited in applications requiring the desirable properties of the hybrid components such as high stiffness and strength, excellent flame resistance, gas/liquid barrier properties, ease of processing, and low cost. The dynamics of the microstructure evolution in these hybrid materials is one critical area for additional study because it will afford the knowledge needed to
tailor the final properties of these interesting materials to specific applications. ACKNOWLEDGEMENTS The funding support of the U.S. National Science Foundation through a grant, NSF-DMR 9733350, from the Division of Materials Research is gratefully acknowledged. The assistance of Dr. Roland Horst from Prof. H. Winter's group at University of Massachusetts, Amherst in extracting the relaxation data with the IRIS software is greatly appreciated. REFERENCES [1] Beall GH, and Quinn CJ: ``Zinc-Containing Phosphate Glasses,'' U.S. Patent 4,940,677 (1990). [2] Beall BH, Dickinson JE, and Quinn CJ: ``Rare earthcontaining zinc phosphate glasses; Alkali resistance, chemical durability; consists of rare earth oxides and at least two alkali metal oxide with tin/aluminum/ and lead oxide,'' U.S. Patent 4,996,172 (1991). [3] Ray NH, Laycock JNC, and Robinson WD: ``Oxide glasses of very low softening point. Part 2. Preparation and properties of some zinc phosphate glasses,'' Glass Technol. 14 (1973) 55-59. [4] Quinn CJ, Frayer PD, and Beall GH: ``Glass-polymer melt blends,'' Encyclopedia of Polymer Science and Technology, 4, J.C. Salamone [ed.], (1996) 2766-2777. [5] Quinn CJ, Beall GH, and Dickinson JE: "Alkali Zinc Pyrophosphate Glasses for polymer blends," Bull. Spanish Soc. Of Ceramics on Glass 31-C (1992) 79-84. [6] Sammler RL, Otaigbe JU, Lapham ML, Bradley NL, Monahan BC, and Quinn CJ: "Melt Rheology of zinc alkali phosphate glasses," J. Rheol. 40 (1996) 285-302. [7] Otaigbe JU, and Beall GH: "Inorganic Phosphate Glasses as Polymers," Trends in Polymer Science 5 (1997) 369-379. [8] Bahn WA, and Quinn CJ: ``Microstructure of low melting temperature glass-poly [aryletherketone] Blends,'' SPE-ANTEC Tech. Papers 49 (1991) 2370-2372. [9] Otaigbe JU, Quinn CJ, and Beall GH: "Processability and Properties of Novel Glass-Polymer Melt Blends," polymer composites 19 (1998) 18-22.
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File: melt-rheology-of-tin-phosphate-glasses.pdf
Title: Melt rheology of tin phosphate glasses
Author: Sunil B. Adalja and Joshua U. Otaigbe
Subject: Journal Article DOI 10.3933/ApplRheol-11-10 published as: Applied Rheology 11:1 (2001) 10
Published: Tue Mar 20 22:13:05 2001
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