Synthesis of a coconut oil-based biopolyol via sequential glycerolysis and amidation; and its subsequent use as a sole polyol for rigid poly(urethane-urea) hybrid foam production.

ABSTRACT:The study investigated an approach to incorporate modified epoxidized soy-based vegetable oil polyol as a replacement for petroleum-based polyether polyol and to substantially reduce the isocyanate loading in the rigid foam formulation. Noncatalytic polymerization of epoxidized bodied soybean oil and ethylene glycol (EG) was carried out in a closed batch reaction. Cleavage of the oxirane rings and hydroxyl group attachment at optimum conditions provided the desired polyol products. The polyols were characterized based on its hydroxyl numbers, acidity, viscosity, iodine number, and Gardner color index for quality purposes. Reactions of oxirane ring and EG were verified by spectroscopic FTIR. Crosslinking performance was evaluated by extractability analysis on the polyurethane (PU) elastomer wafers. Rigid foaming performed at 50 and 75% petroleum-based polyether polyol replacements have shown excellent thermoinsulating and mechanical properties compared with epoxidized soybean oil (ESBO) alone or petroleum-based polyether polyol alone. A reduction of up to 8% of the polymeric diphenylmethane diisocyanate was achieved using the synthesized ESBO-EG-based polyols. A higher average functionality polyol is key component to the reduction of isocyanate in PU synthesis.

Variable angle spectroscopic ellipsometry ͑VASE™͒ is used as a tool to characterize properties such as optical constant, thickness, refractive index depth profile, and pore volume fraction of single and bilayer porous low-k films. The porous films were prepared using sacrificial pore generator ͑porogen͒ approach. Two sets of porous films with open-and closed-pore geometries were measured. Three models were used for data analysis: Cauchy, Bruggeman effective medium approximation ͑BEMA͒, and graded layer. Cauchy, a well-known model for transparent films, was used to obtain thickness and optical constant, whereas BEMA was utilized to calculate the pore volume fraction from the ellipsometric data. The Cauchy or BEMA models were then modified as graded layers, resulting in a better fit and a better understanding of the porous film. The depth profile of the porous film implied a more porous layer at the substrate-film interface. We found 3%-4% more porosity at the interface compared with the bulk for both films. This work shows that VASE™, a nondestructive measurement tool, can be used to characterize single-and multigraded layer porous films quickly and effectively.

In the absence of polymerization, soy-based polyols tend to have inadequate hydroxyl equivalent molecular weights for many critical urethane applications. In this article, the polymerization (bodying) of soybean oil is presented as an effective method to increase the molecular weight of soy-based polyols. When bodying is combined with reaction steps for alcohol addition and acid reduction, soy-based polyols suitable for urethane applications can be synthesized. Two different heat-polymerization approaches, catalyzed-and noncatalyzed-bodied soybean oil (BSBO) were evaluated in continuous and batch processing. The catalyzed-BSBO has lower iodine numbers and high viscosities than the noncatalyzed-BSBO. This approach represents one of the least-costly means to increase the hydroxyl equivalent weights of soy-based polyols.

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Carbon-based electrode materials have been widely used for many years for electrochemical charge storage, energy generation, and catalysis. We have developed an electrode material with high specific capacitance by entrapping graphite nanoparticles into a sol-gel network. Films from the resulting colloidal suspensions were highly porous due to the removal of the entrapped organic solvents from sol-gel matrix giving rise to high Brunauer-Emmett-Teller (BET) specific surface areas (654 m(2)/g) and a high capacitance density ( approximately 37 F/g). An exponential increase of capacitance was observed with decreasing scan rates in cyclic voltammetry studies on these films suggesting the presence of pores ranging from micro (< 2 nm) to mesopores. BET surface analysis and scanning electron microscope images of these films also confirmed the presence of the micropores as well as mesopores. A steep drop in the double layer capacitance with polar electrolytes was observed when the films were rendered hydrophilic upon exposure to a mild oxygen plasma. We propose a model whereby the microporous hydrophobic sol-gel matrix perturbs the hydration of ions which moves ions closer to the graphite nanoparticles and consequently increase the capacitance of the film.

An acylglycerol-based molecule was synthesized by the thermal polymerization (bodying) of soybean oil followed by transesterification with glycerol. Transesterification with glycerol at temperatures greater than 200 C provided the desired polyol prepolymers. The extent of bodying and quantity of glycerol added during the transesterification provided tunability of the polyol molecular weight and functionality. The hydroxyl numbers, acidity, and viscosity of the polyols were characterized. The polyols were evaluated in elastomers and rigid foams. Extractability analyses were performed on the polyurethane elastomer wafers to evaluate crosslinking. Rigid foaming results for the processed soy-based polyol showed excellent physicochemical properties suggesting comparability with a petroleum-based polyether polyol.

Polymers derived from plant oils have attracted major commercial interest and significant attention in scientific research because of the availability, biodegradability, and unique properties of triglycerides. Triglycerides rich in unsaturated fatty acids, such as soybean oil (SBO), are particularly susceptible to chemical modification for desired polymeric materials. Soy-based polyols are important industrial prepolymeric materials that use renewable resources; and can be produced or derived through different processing routes. This review paper discusses previous and recent researches about chemical and biochemical polymerization processes to produce soy-based polyols as prepolymers for the production of polyurethane materials in the form of foams (rigid or flexible) and elastomers. The central goal of these research fields is to find effective reaction routes to increase both equivalent weight and hydroxyl functionality of soy-based polyols while taking into consideration the simplicity and economics of these processes.