Microdispersive interfacial mixing in fast polymerizations

Machuga, S.; Midje, Heather L.; Peanasky, John; Macosko, Christopher W.; Ranz, W. E.

doi:10.1002/aic.690340702

Cited by 20 publications

(20 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This can be a result of a mutual increase of the equilibrium area per polar head-group when the film is in pure water and the fluctuations caused by unbinding [21,22] of the membranes when the film is in excess water. Similar [23] surface-roughening behavior has been observed when a surface-active molecule is formed by reaction at the smooth interface between two incompatible polymers. In Figure 2 a the initial evolution with time of such wrinkles was measured.…”

supporting

confidence: 69%

Neuron‐Like Tubular Membranes Made of Diblock Copolymer Amphiphiles

Battaglia

Ryan

2006

Angew Chem Int Ed

View full text Add to dashboard Cite

The complexity and the functionalities of biological membranes have been recently mimicked [1][2][3][4][5] by synthetic block copolymer amphiphiles. The entirely artificial nature of these polymeric membranes allows an extensive variety of chemistry to be applied to the design of mechanically and chemically enhanced [2] micro-and nanostructures with a tunable range of dimensions and membrane thicknesses.[6] In analogy with biological membranes, polymer membranes have also been found to generate more complex architectures. [7] Myelins are very long (up to a few meters) multilamellar tubules that connect the neuronal cells and together with them make up the intricate network essential for the function of the nervous system and brain.Studies of the water-solid amphiphile interface have revealed that myelins form upon dissolution of membraneforming synthetic amphiphiles. [8][9][10][11][12] Indeed, whilst the morphology of water-amphiphile mixtures is strongly dependent on the concentration, several studies have reported how membrane-forming amphiphiles assemble into different morphologies as a function of the water/amphiphile ratio.

show abstract

supporting

confidence: 69%

Neuron‐Like Tubular Membranes Made of Diblock Copolymer Amphiphiles

Battaglia

Ryan

2006

Angew Chem Int Ed

View full text Add to dashboard Cite

show abstract

“…This second (fast) mixing process seemed to be related to surface instabilities. Machuga et al16 confirmed the observation of other authors that the polyol at the boundary layer diffuses spontaneously and rapidly (<1 s) in the isocyanate to form a well‐mixed intermaterial phase. They found that the dimers that are formed on the boundary layer of the isocyanate and the polyol play an important role in this process.…”

Section: Theory: Reaction Kineticssupporting

confidence: 80%

“…The effect of catalyst on the interfacial process was ambivalent. Wickert et al14 observed a much finer dispersion with catalyst than without, whereas Machuga et al16 detected no difference between catalyzed and uncatalyzed experiments.…”

Section: Theory: Reaction Kineticsmentioning

confidence: 98%

A kinetic investigation of polyurethane polymerization for reactive extrusion purposes

Verhoeven

Padsalgikar²,

Ganzeveld

et al. 2006

J of Applied Polymer Sci

View full text Add to dashboard Cite

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.

show abstract

“…The above rather crude analysis neglects some of the subtleties which have been recently observed, such as the microdispersive interfacial mixing, occurring within fractions of a second, upon contact at the interfacial plane of the reactants (20). This effect would further reduce the scale of segregation in actual RIM systems.…”

Section: Injection Mixingmentioning

confidence: 99%

Rotary injection reaction injection molding (RI‐RIM). Part I: Basic design features

Briscoe

Khan

Richardson

1990

Polymer Engineering & Sci

View full text Add to dashboard Cite

This paper describes the basic design features of a new reaction injection molding (RIM) processing device, Rotary Injection RIM (RI‐RIM). The new design includes a novel mixing concept which furnishes high intermaterial contact area upon shear imposed rotary injection of the RIM components for effective in situ polymerization. This system operates in low pressure and laminar flow conditions, as opposed to the high pressure and turbulent flow, found in conventional RIM systems. The mixing process is described and quantified in terms of the various forces which govern the injection process. A progressive diminution in the average size of the dispersions generated is found with increasing rate of shear, continuous‐phase viscosity, and injection rate. These results are compared with those expected from traditional shear mixing (bulk convective shearing) under comparable conditions and the current system found to be more efficacious. Reaction molding experiments with RI‐RIM using a model polyurethane system are described and the influence of operating conditions on the mechanical properties of the finished moldings are elucidated. A detectable change in the morphology of the system is observed following increase in the total shear strain imparted to the initial mix of the multiphase reactants. It is suggested that the observed change is affected by a segregation between the components of the segmented polymer.

show abstract

Microdispersive interfacial mixing in fast polymerizations

Cited by 20 publications

References 16 publications

Neuron‐Like Tubular Membranes Made of Diblock Copolymer Amphiphiles

Neuron‐Like Tubular Membranes Made of Diblock Copolymer Amphiphiles

A kinetic investigation of polyurethane polymerization for reactive extrusion purposes

Rotary injection reaction injection molding (RI‐RIM). Part I: Basic design features

Contact Info

Product

Resources

About