ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The effects that the inclusion of low concentrations (0 to 0.6 percent by Volume) of cellulosic fibers have on the polymerization of a polyurethane was tested by monitoring the viscosity of a reacting diol-diisocyanate system under isothermal conditions. An increase in viscosity due to the presence of the cellulosic fibers is observed, in addition to the expected rise related to polymer formation. However, a slackening effect appears as more cellulosic fibers are added to the polymerizing medium, in contrast to a system with comparable concentrations of glass fibers. On the basis of reaction kinetics arguments, it is suggested that the hollow nature of the cellulosic fibers and their sorbency play important roles in the effect observed, by reducing the effective concentrations of one of the monomers in the reacting phase, thereby diminishing the overall reaction rate. If similar portions of both monomers are extracted from the bulk of the reacting mass, the reaction is not affected as markedly as when only part of one of the monomers is abstracted. The results found illustrate the type of constraints that arise when certain types of polymerizations are carried out in situ to obtain cellulosic fiber composites.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760282008
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