Modified soy-based vegetable oil polyols were successfully incorporated as a replacement for conventional polyols to produce flexible slabstock polyurethane foams. The oil was characterized for its hydroxyl value and fatty acid composition. The modified oils had higher hydroxyl values and lower unsaturated acids than regular unmodified oils. Three different modified polyols were used to investigate the reactivity with isocyanates. The effects on the foaming reaction of two different isocyanates, namely TDI and MDI, were investigated. The reactions were also carried out with a mixture of polyols containing synthetic polyols and vegetable oil-based polyols to delineate the effect of each component. FTIR technique was used to identify the sequence of chemical reactions during the foaming process. The effect of water levels and isocyanate content on the kinetics of the foaming reaction was investigated. Information regarding the formation of hard and soft segments with the varying compositions was obtained. As the water content increased, the amount of the hard segment and urea formation increased in both soy oil polyols and synthetic polyols. Increased synthetic polyols in the mixture increased the rate of reaction and phase mixing due to the availability of primary hydroxyl groups. Scanning electron microscopy (SEM) and small-angle X-ray scattering (SAXS) were used to probe the morphology. As the water content increased, the cell size increased. At lower water content a more uniform cell structure was evident and at higher water levels hard domain size increased.

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Abstract-We propose a principled algorithm for robust Bayesian filtering and smoothing in nonlinear stochastic dynamic systems when both the transition function and the measurement function are described by non-parametric Gaussian process (GP) models. GPs are gaining increasing importance in signal processing, machine learning, robotics, and control for representing unknown system functions by posterior probability distributions. This modern way of "system identification" is more robust than finding point estimates of a parametric function representation. In this article, we present a principled algorithm for robust analytic smoothing in GP dynamic systems, which are increasingly used in robotics and control. Our numerical evaluations demonstrate the robustness of the proposed approach in situations where other state-of-the-art Gaussian filters and smoothers can fail.

Model butanediol–MDI–polypropylene oxide polymers have been synthesized to explore the structure–property relationships in urethane/polyether polymers. The results of mechanical, thermal, and spectroscopic analyses agree remarkably well. The phase mixing in these polymers decreases with increasing hard‐segment length, while the hard‐segment stability increases with increasing hard‐segment length. This is demonstrated clearly by dynamic mechanical, differential scanning calorimetry, infrared, and NMR studies. The importance of hydrogen bonding to the stability of the hard segment is strongly supported by the variable‐temperature infrared experiments. The critical hard‐segment size for phase segregation was shown to be two butanediols per hard segment. The temperature limit of the flatness of the storage modulus was tied to the thermal stability of the hard‐segment hydrogen bonding which is controlled largely by the length of the hard segment and the extent of the hydrogen bonding.