Foam stability and polymer phase morphology of flexible polyurethane foams synthesized from castor oil

Abstract

Foam stability and segmented polymeric phase morphology of polyurethane foams synthesized partially and completely from castor oil are investigated. Preliminary analysis of the impact of alterations in the polymeric phase on macroscopic stress dissipation in foams is also carried out. The stability and morphology show unique trends depending on the concentration of castor oil used in foam synthesis. While low and intermediate concentrations of castor oil does not significantly affect the foaming process; at high concentrations, the volumetrically expanding liquid matrix remains in a nonequilibrium state during the entire foaming period, resulting in significant foam decay from top. This increases the final foam cell density and decreases the plateau border thickness at bottom. In the polymeric phase of castor oil based foams, the fraction of monodentate urea increases at the cost of non-hydrogen bonded urea. These monodentate urea domains undergo flocculation in foams synthesized completely from castor oil, thus prominently modifying the segmented morphology. The glass transition temperature of soft segments of partially substituted foams shows moderate increase, with indications of phase mixing between the polyether and castor oil generated urethane domains. Foams synthesized entirely from castor oil have significant sol fraction due to unreacted oligomers. The microscopic alterations in polymeric phase reduce the elastic recovery of partially substituted castor oil foams compared to its viscous dissipation under an applied stress. V C 2014Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40668.

Urethane‐forming reaction kinetics and catalysis of model palm olein polyols: Quantified impact of primary and secondary hydroxyls

“…However, both materials show a diffused shoulder like peak at 0.05 Å −1 corresponding to the interdomain spacing of 12.6 nanometers. This result compares well to the reported interdomain separation of scattering domains in polyurethane foams; however, the scattering intensity in this study is very low . This is most likely due to the fact that the NOPs in this study act like cross‐linkers in polyurethane elastomers, which adds to the mixing of the soft and hard segment domains.…”

“…Phase images of the elastomers collected via AFM are presented in Figure . The images were collected via tapping mode, and hard domains are represented by lighter colors and softer matrix by darker colors . The elastomer based on M‐60 NOP is composed of the small structures agglomerated into lamella like larger domains.…”

Synthesis of bio-castor oil polyurethane flexible foams and the influence of biotic component on their performance

“…Elodie et al [33] obtained thermoset polyurethane which based on CO with three different diisocyanates: TDI (toluene diisocyanate), IPDI (isophorone diisocyanate) and HDI (hexamethylene diisocyanate). C. Sharma et al [34] investigated the different weight fraction of castor oil in the hydroxyl component of polyol blend (polyether polyol and castor oil) of petroleum based foam and castor oil based foam. However, there has been little works involving the effect of the castor oil composition content in prepolymer (CO, PEG and MDI) on the properties of the pure castor oil based polyurethane flexible foams.…”

Bio-based polyurethane prepared from Kraft lignin and modified castor oil

“…This provides a hydroxyl value of between 160 and 180 mg KOH g -1 [4,5]. However, this low hydroxyl value along with the presence of secondary hydroxyls results in low functionality and low reactivity [6,7], leading to low crosslinking density, which consequently produces semi-flexible and semi-rigid materials among other limitations [8]. Sharma et al [7] investigated flexible polyurethane foams synthesized partially and completely from castor oil.…”

“…However, this low hydroxyl value along with the presence of secondary hydroxyls results in low functionality and low reactivity [6,7], leading to low crosslinking density, which consequently produces semi-flexible and semi-rigid materials among other limitations [8]. Sharma et al [7] investigated flexible polyurethane foams synthesized partially and completely from castor oil. They showed that foams made from 100% of castor oil were unstable and collapsed indicating the inferior reactivity of castor oil with isocyanate.…”