Foam Rheometer: Its Principle and Applications

Kostrzewski, W.

doi:10.1177/0021955x8502100608

Cited by 11 publications

(10 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Traditionally, volume expansion was measured by detecting the position of the foam with a light weight float placed on top of the expanding mixture (Bailey and Critchfield, 1981;Hanusa and Hunt, 1982). The float, however, interacted physically with the foam distorting the volume rise determination (Kostrzewski, 1985).…”

Section: Experimental Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Volume Rise During Flexible Urethane Foaming

Artavia

Macosko

Priester

et al. 1993

Polymer Reaction Engineering

View full text Add to dashboard Cite

During the formation of flexible urethane foams, isocyanate and water react to form urea dimers and oligomers which eventually segregate as a microdisperse solid phase. The role that urea segregation plays on reaction kinetics and flowability during foaming is examined in this work. Temperature and volume rise profiles were measured for a series of foam systems by varying the amount of water (2-6 pphp), isocyanate (90, 110, 130 index), and amine or tin catalysts in the formulation . Model calculations showed that 84-90% conversion of isocyanate (NCO) groups was required to form a crosslinked polymer network. However, volume rise was found to stop at 40-70% NCO conversion. This indicates that gelation is due to phase separation rather than covalent crosslinking. A sudden acceleration in the rate of reaction (dT/dt), detected before foams reached a constant volume, is thought to indicate rnicrophase separation during foaming. A mechanism is presented to correlate temperature and volume rise profiles with urea microphase segregation during reactive urethane foaming. The blowing efficiency during foaming ranges between 55-82% as the concentration of isocyanate (90-130 index) or tin catalyst (0.2-0.4 pphp) is increased in the formulation, although it appears relatively independent of the water or amine catalyst levels used in this study. It was also found that addition of glycerine to the foaming system disrupted the urea microphase separation process, and increased the blowing efficiency to 85%. tcurrent address:

show abstract

Section: Experimental Methodsmentioning

confidence: 99%

“…Cell opening in flexible foams, however, occurs well before the polymerization is completed (Van Thuyne and Zeegers, 1978;Rossmy eta!., 1981;Kostrzewski , 1985). Woods (1987) suggested that at the time of cell opening polymer strength was low, with a considerable fraction of the isocyanate groups still unreacted.…”

Section: Introduction and Objectivesmentioning

confidence: 99%

Volume Rise During Flexible Urethane Foaming

Artavia

Macosko

Priester

et al. 1993

Polymer Reaction Engineering

View full text Add to dashboard Cite

show abstract

“…

…”

mentioning

confidence: 99%

“…The use of an ultrasonic or Fluidyne rise rate apparatus as a performance test for polyurethane foam systems has been available for over 20 years [1-3,7,91. The use of computer assisted processing of the rise profile and rise rate data has also been documented [9,11].Our early development work presented here was focused on replacing the standard CFT with an ultrasonic rise rate test for the commercial polyurethane foam producer. We concentrated on developing a test that was simple, precise and inexpensive.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Ultrasonic Rise and Adiabatic Temperature Evaluation (URATE) of Polyurethane Foams

Autenrieth

Gutowsky

Burks

1991

Journal of Cellular Plastics

View full text Add to dashboard Cite

HISTORICAL F or as long as polyurethane foaming reactions have been known, polyurethane researchers have been challenged to fully measure or &dquo;fingerprint&dquo; this complex reaction's characteristics [1][2][3][4][5][6][7][8][9]. Researchers have attempted to devise apparatus that were reliable, accurate and precise. The polyurethane foam producer needs a device that is inexpensive, user friendly and free from operator variability. The commercial polyurethane foamer needs to extrapolate data from the laboratory to large scale production equipment. To complicate these many requirements, one has to consider that virtually all the components which comprise a polyurethane foam formulation contribute to and thus have an effect on the overall reaction rate. Therefore, it is little wonder that numerous tests from the simple to the complex [1-3,5-9] have been developed to study the reactivity of polyurethane foam systems, and these investigations will probably continue for years to come in this dynamic area [8].In the area of flexible and semiflexible polyurethane foams, the cup foam test (CFT) has been utilized for over 25 years [10]. The CFT can be Downloaded from 433 URATE of Polyurethane Foams easily performed in the laboratory or on production equipment and can measure several critical performance parameters of polyurethane foam systems. The CFT can accurately measure the cream time (CT), top of cup time (TOC), string gel time (GT), end of rise time (EOR) and free rise density (FRD) of polyurethane foams. In addition, the tack free time has also been used to approximate the demold time for a polyurethane foam system. The CFT is routinely performed using a bench top mixer in the laboratory. Some of the common uses of the CFT in the laboratory are listed below: . monitor the purity of components and raw materials . monitor the consistency of blended formulations . train new personnel in formulation variables . perform a QC performance test for polyurethane foam systems The CFT has also found extensive use on production equipment and some of these uses are listed below: · monitor component ratio (index) of the machine · monitor mixing efficiency and consistency · identify contamination of the polyurethane chemicals · monitor machine delivery (shot weight) consistency · collect the reaction profile data listed above Through the use of Statistical Process Control (SPC) charts, the CFT parameters from the laboratory and/or production line are routinely plotted to monitor both chemical and mechanical processes.It was recognized that three of the five CFT reaction parameters involved a height measurement. In addition, the consistency of the reaction parameters generated on the CFT is always questionable due to operator to operator variability (subjectivity). For these reasons, we turned our attention several years ago to a logical extension of the CFT which is the ultrasonic rise profile apparatus. The use of an ultrasonic or Fluidyne rise rate apparatus as a performance test for polyurethane foam systems has been avail...

show abstract

Numerical simulation of mold filling in foam reaction injection molding

Seo

Youn

Tucker

2003

Numerical Methods in Fluids

View full text Add to dashboard Cite

SUMMARYA numerical simulation of reaction injection molding (RIM) of polymeric foam is developed, using a ÿnite volume method (FVM). In this study we predict mold ÿlling with a variable-density uid that ÿlls a mold by self-expansion. We deal with two-dimensional, isothermal cases. With the assumptions of ideal mixing and rapid bubble nucleation, the foam is modelled as a continuum with a time-dependent density. The continuum is assumed to be a Newtonian uid. We develop a pressure-based FVM for unstructured meshes that includes the SIMPLE algorithm with treatment of uid compressibility. Cellbased, co-located storage is used for all physical variables. To treat the moving interface, an explicit high-resolution interface capturing method is used. Foam ow in a slit is investigated, and the numerical calculations are in good agreement with an approximate analytic solution. For fountain ow in a rectangular cavity, the shape of the ow front is atter and the traces of the particles are more complicated for an expanding foam than for a constant-density uid. An example of mold ÿlling by an expanding foam demonstrates the geometric exibility of the method.

show abstract

Foam Rheometer: Its Principle and Applications

Cited by 11 publications

References 2 publications

Volume Rise During Flexible Urethane Foaming

Volume Rise During Flexible Urethane Foaming

Ultrasonic Rise and Adiabatic Temperature Evaluation (URATE) of Polyurethane Foams

Numerical simulation of mold filling in foam reaction injection molding

Contact Info

Product

Resources

About