Curing kinetics of a rigid polyurethane foam formulation

Marciano, J. H.; Rojas, A. J.; Williams, Roberto J. J.

doi:10.1016/0032-3861(82)90250-6

Cited by 34 publications

(28 citation statements)

References 6 publications

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“…The conversion data for each DBTDL catalyst concentration were found to approximately fit second‐order reaction kinetics, as shown in Fig 6. This is in agreement with the work of Nakamichi and Ishidoya,9 who performed isothermal FTIR on a series of DBTDL‐catalysed urethane coatings, and also with that of Marciano et al ,21 who showed that second‐order kinetics gave a good fit for the whole conversion range up to the gel point, of a similarly catalysed system. Furthermore, the dependence of the reduced second‐order rate constant on DBTDL concentration is shown (Fig 6 inset) to be approximately linear, which is in agreement with the work of Nakamichi and Ishidoya,9 and also with Marciano et al 21 for DBTDL concentrations greater than 2.6 mol m −3 (equivalent to 2.8 × 10 −3 g per mass of polyol, for the 700T/xDBTDL/MDI system)…”

Section: Resultssupporting

confidence: 91%

Cure and properties of unfoamed polyurethanes based on uretonimine modified methylene-diphenyl diisocyanate

et al. 2000

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Section: Resultssupporting

confidence: 91%

Cure and properties of unfoamed polyurethanes based on uretonimine modified methylene-diphenyl diisocyanate

et al. 2000

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“…In this, 50 g of the polyol mixture was reacted with the same weight ratio of isocyanate, as in the case of molded foams, at the same initial temperature. The phenomenon of a sudden rise in viscosity at the gel point was used to experimentally determine the gel time by moving a glass rod in the reacting liquid until its movement was resisted [24,25]. The rise time was noted as the time at which the rise of the foam stops.…”

Section: Foaming Processmentioning

confidence: 99%

Formation and characterization of polyurethane—vermiculite clay nanocomposite foams

Patro

Harikrishnan

Misra

et al. 2008

Polymer Engineering & Sci

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Nanocomposites of rigid polyurethane foam with unmodified vermiculite clay are synthesized. The clay is dispersed either in polyol or isocyanate before blending. The viscosity of the polyol is found to increase slightly on the addition of clay up to 5 pphp (parts per hundred parts of polyol by weight). The gel time and rise time are significantly reduced by the addition of clay, indicating that the clay acts as a heterogeneous catalyst for the foaming and polymerization reactions. X-ray diffraction and transmission electron microscopy of the polyurethane composite foams indicate that the clay is partially exfoliated in the polymer matrix. The clay is found to induce gas bubble nucleation resulting in smaller cells with a narrower size distribution in the cured foam. The closed cell content of the clay nanocomposite foams increases slightly with clay concentration. The mechanical properties are found to be the best at 2.3 wt% of clay when the clay is dispersed in the isocyanate; the compressive strength and modulus normalized to a density of 40 kg/m 3 are 40% and 34% higher than the foam without clay, respectively. The thermal conductivity is found to be 10% lower than the foam without clay.

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“…The kinetics of urethane formation are complex and have been studied by the adiabatic temperature rise method. To facilitate comparison with the results of Rojas et al (1982), we use the second-order kinetics proposed by Marciano et al (1982). The usual form for a batch reactor is:…”

Section: Polymerization Reaction Ratementioning

confidence: 99%

“…The above kinetic expression has also been obtained by conducting adiabatic temperature rise studies up to gelation (Lipshitz et al, 1977;Marciano et al, 1982). But the formulation used by them did not contain a blowing agent.…”

Section: Polymerization Reaction Ratementioning

confidence: 99%