GREEN BIOMASS MATERIALS IN POLYURETHANE FOAMS

Flexible polyurethane foams were prepared using naturally-derived mate rials as alternatives to conventional auxiliary blowing agents. This r esearch was based on the concept held by some that natural chemicals a re better as a part of industrial ecology. The authors have attempted to define the foam manufacturing suitability of natural chemicals, but have not defined or defended the policy implications of such choices. Natural chemicals are often less suitable than those refined from pet roleum and may then need some environmental credit related to greater discharge to be viable substitutes. Modest decreases in density (relat ive to foams without any auxiliary blowing agent) were obtained with t he addition of solid CO2, but other physical properties were not measu red. It is unclear whether the reduction in density is a result of the phase change of CO2 from solid to liquid within the polyurethane cell matrix or simply a bubbling effect of CO2 in solution causing voids w ithin the final product. Although it was anticipated that the high boi ling point of limonene, from citrus peels, would negate effectiveness as an auxiliary blowing agent, there were analogous decreases in foam density. The observed effect might be rationalized by the significant vapor pressure of limonene at temperatures lower than the boiling poin t. The limonene may be swept from the foam system coincident with the loss of in situ generated CO2. Isoprene, naturally emitted from decidu ous vegetation as well as from the combustion of carbonaceous fuels, p rovides a useful, if not complete, range of foam densities and may the n be a partial substitute for halogenated auxiliary blowing agents. Sw itching from methylene chloride to isoprene as the auxiliary blowing a gent of choice would immediately decrease organic emissions from polyu rethane foam plants by 20 percent (molecular weight effect). Regulatio n as a VOC and the residual acrid odor may be potential drawbacks to c ommercial utilization of isoprene.