Rheo‐kinetic measurement of thermoplastic polyurethane polymerization in a measurement kneader

Verhoeven, V. W. A.; Vondel, M. P. Y. Van; Ganzeveld, K. J.; Janssen, L.P.B.M.

doi:10.1002/pen.20163

Cited by 10 publications

(16 citation statements)

References 15 publications

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“…In that case the polymerization is dominated by diffusion phenomena. Verhoeven et al [218] pointed out that diffusion limitations can be most noticeable during the initial stage of the reaction depending on the miscibility of monomers and also at high conversions.…”

Section: Methodsmentioning

confidence: 99%

“…To overcome these problems when mixing is a determinant step, the general approach is to use a batch mixer and to deduce the viscosity and shear rate from the speed and torque measurements. Verhoeven et al [218] investigated the rheo-kinetics of thermoplastic polyurethanes (TPU) formation in a measurement kneader at high temperature. However, due to the amount of polymer introduced in such apparatus and the low heat conductivity of polymers, self heating phenomenon by viscous dissipation does not allow to control well the operating temperature.…”

Section: New Rheological Devicesmentioning

confidence: 99%

“…Furthermore, molten polymers may be non-newtonian and their properties may change along the processing machine (spatial and temporal evolution) due to the mixing process and/or chemical reaction progress. As previously explained, the diffusion process has also to be considered since it can become a significant limiting step at the mole- 218  Carl Hanser Verlag, Munich Intern. Polymer Processing XXII (2007) 3 cular scale of mixing and as far as chemical reactions are present, their rates have to be known.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Reactive Processing of Thermoplastic Polymers: A Review of the Fundamental Aspects

Cassagnau

Bounor‐Legaré

Fenouillot

2007

International Polymer Processing

100

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This work is dedicated to Dr. Alain Michel for his retirement and in memory of Prof. Morand Lambla. Dr. Michel and Prof. Lambla were the pioneers of the development of reactive processing in FranceThe review is devoted to the fundamental aspects of the reactive processing of thermoplastic polymers. First of all, some reactive processing examples, including polymer grafting (vinyl silane, maleic anhydride) and/or functionalization, bulk polymerization (urethane, lactams, acrylate, e-capolactone), polyester modification and new copolymers synthesis, are presented. From a fundamental point of view, the review covers the state of the art in the domains of rheology (specifically modelling of rheo-kinetics), diffusion and mixing in highly viscous reactive or non reactive media. Finally, 1, 2 and 3-D simulation of the reactive extrusion process in twin-screw extruder is reported at the end of the review.

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Section: Methodsmentioning

confidence: 99%

Section: New Rheological Devicesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reactive Processing of Thermoplastic Polymers: A Review of the Fundamental Aspects

Cassagnau

Bounor‐Legaré

Fenouillot

2007

International Polymer Processing

100

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“…The samples obtained in this way were analyzed through SEC. The SEC procedure was described in a previous publication 20. The experiments for system 1 were performed at five different temperatures (150, 160, 170, 180, and 200°C).…”

Section: Methodsmentioning

confidence: 99%

A kinetic investigation of polyurethane polymerization for reactive extrusion purposes

Verhoeven

Padsalgikar²,

Ganzeveld

et al. 2006

J of Applied Polymer Sci

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ABSTRACT:The effects of the reaction conditions on the kinetics of two different polyurethane systems were investigated. To do so, three different kinetic methods were compared: adiabatic temperature rise (ATR), measurement kneader, and high-temperature measurements. For the first polyurethane system, consisting of 4,4-diphenylmethane diisocyanate (4,4-MDI), butane diol, and a polyester polyol, the reaction conditions did not seem to matter; a kinetically controlled reaction was implicated for all reaction conditions. The reaction was second order in isocyanate concentration and 0.5th order in catalyst concentration and had an activation energy of 52 kJ/mol. The second polyurethane system consisted of a mixture of 2,4-diphenylmethane diisocyanate and 4,4-MDI, methyl propane diol, and a polyester polyol. For this system, each of the three measurement methods showed different behavior. Only at a low catalyst concentration did the ATR experiments show catalyst dependence; at higher catalyst levels and for the other two measurement methods, no catalyst dependence was present. Furthermore, the ATR experiments proceeded much faster. Presumably, for this system, the rapid diffusion interfacial of the species present was hindered by the presence of bulky oligomer molecules. The result was a diffusion limitation reaction at low conversions and an inhomogeneous distribution of species at higher conversions.

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“…Note that t max also represents the reaction time needed to form a polymer network. The values of can be correlated to the viscosity of the system by the following relationships [114]:…”

Section: Simultaneous Effects Of Mixing Chemical Reaction and Molecmentioning

confidence: 99%

Evolution of Nonlinear Rheology and Network Formation during Thermoplastic Polyurethane Polymerization and Its Relationship to Reaction Kinetics, Phase Separation, and Mixing

Jana

2010

Nonlinear Dynamics With Polymers

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Understanding the evolution of nonlinear rheological properties during polymerization has been of significant industrial and academic interest [1]. The industrial interest originated from the design, operation, and control requirements of polymerization processes [2,3]. The industrial polymerization processes cover a broad spectrum from bulk production of thermoplastics, such as polyolefins, to production of thermosets, such as tires, comprising many simultaneous steps, such as chemical reactions and mixing, followed by compounding, molding, and cross-linking reactions [4,5]. The most relevant and widely documented rheological property for success of industrial processes is the viscosity of the polymerizing medium, which directly influences mass, heat, and momentum transfer processes. The academic interest, on the other hand, has its roots in utilizing rheology as a valuable tool to understand the properties of polymer chains whether in bulk, in solution, or in a polymerizing medium [6]. Monitoring the changes in rheological properties, such as normal stresses, relaxation times, storage, and loss moduli, which are usually nonlinear functions of time, temperature, and morphology, has undeniable significance in providing insights into structure and properties of polymers as they develop during polymerization or during shape-forming operations such as of extrusion, injection molding, casting, and film blowing, to name a few.The nonlinear rheological properties of growing polymer chains, irrespective of the growth mechanisms -such as free-radical or step-growth -are governed by similar parameters. Chemical structure, flexibility, and mobility of chains, the available free volume during polymerization, the degree of conversion, the extent of chain entanglements, the degree of phase separation, and the presence of chemical or physical cross-links are a few of the morphological features and physical phenomena [7] with strong influence on polymerization.

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Rheo‐kinetic measurement of thermoplastic polyurethane polymerization in a measurement kneader

Cited by 10 publications

References 15 publications

Reactive Processing of Thermoplastic Polymers: A Review of the Fundamental Aspects

Reactive Processing of Thermoplastic Polymers: A Review of the Fundamental Aspects

A kinetic investigation of polyurethane polymerization for reactive extrusion purposes

Evolution of Nonlinear Rheology and Network Formation during Thermoplastic Polyurethane Polymerization and Its Relationship to Reaction Kinetics, Phase Separation, and Mixing

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