Soy-Based Adhesives with 1, 3-Dichloro-2-Propanol as a Curing Agent
Keywords:Adhesive, 1, 3-dichloro-2-propanol, shear strength, soy protein, water resistance, wood composites
AbstractIncreasing concern over the impact of formaldehyde on human health has prompted a need for a formaldehyde-free wood adhesive. In this study, we investigated a new formaldehyde-free wood adhesive system consisting of soy protein (SP) and 1, 3-dichloro-2-propanol (DCP). DCP served as a crosslinking agent for SP. The shear strength of wood composites bonded with a SP-DCP adhesive depended on the SP/DCP weight ratio and the reaction conditions such as reaction time and reaction temperature under which the SP-DCP adhesive was prepared. For a given SP/DCP weight ratio, the higher the reaction temperature, the higher the shear strength. Under the same reaction conditions, increasing the SP/DCP weight ratio, i.e., decreasing the relative amount of DCP in the adhesive, resulted in a decrease in the shear strength and water resistance of the resulting wood composites. Of all the SP/DCP weight ratios studied. 6:1 SP/DCP weight ratio at 85°C for 1.0 h gave the highest shear strength in the resulting wood composites. In terms of the shear strength, the 8:1 and 10:1 SP/DCP weight ratios were comparable to each other and were only slightly lower than with the 6:1 SP/DCP ratio. Further increasing the SP/DCP ratio to 12:1 or 15:1 greatly decreased the shear strength. The shear strength slightly increased with pressing temperature in the range of 100°C to 160°C at a press time of 5 min. Press times in the range of 1 min to 9 min had insignificant effects on the shear strength at a press temperature of 140°C. Storage of SP-DCP adhesive at room temperature for one or two days did not significantly affect the shear strength. However, a significant reduction of the shear strength was observed after the adhesive was stored at room temperature for 5 days. Wood composites bonded with a SP-DCP adhesive did not delaminate after they underwent a water-soaking-and-drying test and a boiling-water test. The crosslinking reactions between SP and DCP are discussed in detail.
Baumann, M. G. D., L. F. Lorenz, S. A. Batterman, and G.-Z. Zhang. 2000. Aldehyde emission from particle-board and medium density fiberboard products. Forest. Prod. J.50(9):75-82.nHeck, H. D., M. Casanova, and T. B. Starr. 1990. Formaldehyde toxicity—new understanding. Crit. Rev. Toxicol.20(6):397-426.nHenderson, J. T. 1979. Volatile emissions from the curing of phenolic resins. Tappi J.62:9396.nLambuth, A. L. 1977. Soybean glues: Pages 172-180 in I. S. Skiest, ed. Handbook of adhesives, Van Nostrand Reinhold, New York, NY.nLambuth, A. L. 1989. Protein adhesives for wood. Vol. 2: 1-30 in A. Pizzi, ed. Wood adhesives-chemistry and technology, Mercel Dekker, Inc., New York.nLiu, K. 1997. Soybeans—chemistry, technology, and utilization. International Thomson Publishing, New York, NY.nMarutzky, R. 1989. Release of formaldehyde by wood products. Vol. 2:307-387, in A. Pizzi, ed. Wood adhesives-chemistry and technology, Marcel Dekker, Inc., New York, NY.nMeyer, B., and K. Hermans. 1986. Formaldehyde release from wood products: An overview: Pages 1-16 in B. Meyer, B., A. K. Andrews, and R. M. Reinhardt, eds. ACS symposium series 316-Formaldehyde release from wood products. American Chemical Society, Washington, DC.nPerera, F., and C. Petito. 1982. Formaldehyde: A question of cancer policy? Science216 (4552): 1285-1291.nSellers, T., Jr. 2001. Wood adhesive innovations and applications in North America. Forest. Prod. J.51(6): 12-22.nSwenberg, J. A., W. D. Kerns, R. I. Mitchell, E. J. Gralla, and K. L. Pavkov. 1980. Induction of squamous cell carcinomas of the rat nasal cavity by inhalation exposure to formaldehyde vapor. Cancer Res.40(9):3398-3402.n
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