Strength and Durability of Aklylresorcinolic Adhesives from Estonian Oil Shale Kerogen

Estonian scientists have developed adhesives from the kerogen in Estonian oil shale. The adhesives, based on a series of alkylresorcinols extracted from the kerogen, have distinct economic and environmental advantages over resorcinol-based resins for wood laminating. In this study we evaluated their unaged shear strength and wood failure in bonded hard maple specimens and the change in these properties after elevated temperature aging in constant wet and dry exposures. Based on these studies, the adhesives are quite comparable in strength, although small but statistically significant differences are detected in both unaged and aged specimens. They should have comparable service life in constant service conditions. The major difference between the adhesives is the low wood failure in specimens bonded with alkylresorcinolic adhesives. Low wood failure suggests the alkylresorcinolic adhesives may be sensitive to cyclic swelling and shrinking. Increasing adhesive failure may not be a problem with softwood lumber or with different bonding conditions, but further exploration will be required before alkylresorcinolic adhesives could be accepted as equal substitutes for resorcinolic adhesives in structural laminates for exterior use.

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