Effect of vegetable‐based polyols in unimodal glass‐transition polyurethane slabstock viscoelastic foams and some guidance for the control of their structure–property behavior. I

Abstract

ABSTRACT:We investigated the synthesis and structureproperty behaviors of two types of vegetable-oil polyols (soy oil and castor oil) and their use in viscoelastic (VE) polyurethane foams (PUFs). This article is the first in a two-part series. In this initial part, we principally address the dynamic mechanical analysis (DMA) behavior of these foams in conjunction with information on the cellular morphology, sol fraction, and rise and reaction temperature profile behavior (the latter two parameters were determined during the foaming process). Particular emphasis is placed on the DMA damping characteristics, which represent one of the most critical parameters in the application of VE PUFs. It is also shown that the damping characteristics could be modified in such foams by the variation of the isocyanate/hydroxyl (Â100) index, the addition of plasticizer, and in the case of soy polyols, the soy content. The frequency dependence of the VE PUFs is also briefly addressed. In the second article in this series, which directly follows this article, we further address the details of other relevant physical properties of these same foams in view of their applied nature.

Impact of the hard‐segment concentration on highly resilient polyurethane foams based on palm olein polyol

“…However, with increased concentration of E‐135 NOP, the tan δ broadened. A reduced intensity and a broadening of tan δ was correlated with the increased phase mixing of hard and soft segments in the polymer matrix of the HR‐molded polyurethane foams . Therefore, the replacement of Poly‐G 85‐29 polyether polyol with E‐135 NOP appeared to lead to the reduced separation of hard‐ and soft‐segment domains in the polymer matrix; this was correlated with the observed reduction in resilience and an increase in the energy‐absorbing properties.…”

“…A notable increase in the energy absorption is potentially indicative of increased phase mixing between the hard and soft segments of the polyurethane matrix. Indeed, a previous study with viscoelastic foams indicated that the addition of the NOPs increased the phase mixing of hard and soft segments …”

“…NOPs have been used in most polyurethane products as a partial replacement for petroleum‐based polyether polyols. However, the level of NOP substitution has been limited by the impact of the NOPs on the performance of the specific polyurethane application . In previous studies, researchers have systematically examined the impact of NOPs on the properties of viscoelastic foams, and the results demonstrate that the NOPs increased the load‐bearing properties of the viscoelastic foams, and this potentially resulted in density reduction .…”

“…However, the level of NOP substitution has been limited by the impact of the NOPs on the performance of the specific polyurethane application . In previous studies, researchers have systematically examined the impact of NOPs on the properties of viscoelastic foams, and the results demonstrate that the NOPs increased the load‐bearing properties of the viscoelastic foams, and this potentially resulted in density reduction . In addition, the incorporation of NOPs reduced the ordering of hard‐ and soft‐segment domains, and this resulted in reduced resilience and increased hysteresis of the foams; this is a performance advantage for viscoelastic foams .…”

Effects of MDI–PPG molecular weight on the thermorheological behaviour of MDI–isocyanate based bituminous foams

“…However, taking into account that only a fraction of the added MDI-PPG is consumed, this shift is partially attributable to a plasticizing effect of the prepolymer [1,27]. Consequently, this result suggests enhanced mechanical properties at low in-service temperatures, since modified bitumens would exhibit higher resistance to thermal cracking.…”