What's sweet, green and sticky?
By Jonathan Beard RESIN glues and coatings can now be made from sugar instead of refined petroleum products, according to a chemist in the US who has applied for a patent on the new process. Navzer Sachinvala of the US Department of Agriculture says that sugar-based epoxies can do everything that existing oil-based epoxies can, while providing sugar farmers and producers with a money-spinner. The new glues are environmentally sound too, since sugar is a renewable resource. In standard glues, epoxy groups form polymers with a petrochemical, normally epichlorhydrin and bisphenol-A, derived from oil. In Sachinvala’s glue, epoxy groups are attached to sucrose molecules instead of a petrochemical, using reagents including oxygenated vinegar. By varying the constituents, hundreds of glues and coatings with different properties can be created. But Sachinvala won’t reveal more details until the patent is granted. “Any of the materials available in oil-based epoxies can be made from sucrose,” he says, claiming that sugar-based epoxies are stronger and hold up better at temperatures over 200 °C compared with oil-based epoxies. The USDA has just signed a deal with Cajun Materials Group of Louisiana to commercialise sucrose glues, which it plans to sell in the familiar twin tubes of resin and hardener. “But self-curing sugar-based epoxies, in one tube, are already under development,