STUDIES IN THE CONTROL OF PROPERTIES OF POLYURETHANE FOAMS
STUDIES IN THE CONTROL OF PROPERTIES OF POLYURETHANE FOAMS
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Date
1979-02
Authors
OKORO , OGBOBE AUGUSTINE
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Abstract
There are a lot of local polyurethane foam manufacturers
in Nigeria who appear not to have properly correlated
the effect of the various foam ingredients on foam
properties. The effect of some of the variables in polyurethane
foam preparation on foam properties have been
investigated, Excess Tolylene di-isocyanate (TDI) in
flexible polyurethane foam formulation has no significant
effect on physical properties but trace amounts of
water in the form of moisture can affect foam properties
significantly. Trace amounts of sodium hydroxide
solution and sodium bicarbonate in flexible foam formulations
respectively catalyze polyurethane foam reactions
and give rise to crumbling foams. Increasing amount of
freon used with a fixed amount of water gives foams of
better appearance than when water is used alone. It was
also observed that increase in rise height decreases
foam density while tensile stress at break and initial
modulus are high at low rise heights. Flexible foams
have low compressive stresses before stiffening occurs
and a pronounced yield point which decreases with decrease xii.
in density. Flexible fcaras have a comparatively low
hysteresis loss and hence good resilience. The density
of rigid foams decrease with increase in blowing agent
concentration. Rigid foams have high compressive stresses,
undefined yield points and large hysteresis losses. The
thermal conductivity of rigid foams (density 34-23 kgm )
increased with decrease in foam density.
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Keywords
POLYURETHANE FOAMS, POLYURETHANE FOAMS