Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2014
Publication Date: 8/9/2014
Citation: He, Z., Chapital, D.C., Cheng, H.N., Klasson, K.T., Olanya, O.M., Uknalis, J. 2014. Application of tung oil to improve adhesion strength and water resistance of cottonseed meal and protein adhesives on maple veneer. Industrial Crops and Products. 61:398-402.
Interpretive Summary: Cotton is one of the most important non-food crops in the world. Much of the cotton land area in the US is located in the southern and southeastern region which includes Georgia, Alabama, Arkansas, North Carolina, Mississippi, and Texas. Thus, enhanced utilization of cottonseed will increase the profitability of cotton production in this region and elsewhere. In this work, we demonstrated cottonseed meal-based products show promise in serving as environment-friendly wood adhesives. Furthermore, the low water resistance of cottonseed meal-based adhesives could be improved by the addition of tung oil. Based on the data in this work, we recommend the addition of 0.1% tung oil for economics and convenience. The results of this research provide useful information on cottonseed meals as one of renewable sources of wood adhesives.
Technical Abstract: Cottonseed meal-based products show promise in serving as environment-friendly wood adhesives. However, their practical utilization is currently limited due to low durability and water resistant properties. In this research, we tested the improvement of adhesion strength and water resistance of cottonseed meal-based adhesives by the addition of tung oil. Our data showed that the shear strength of maple wood strips glued at 100 degrees C by water-washed cottonseed meal (WCM) and cottonseed protein isolate (CSPI) increased by 19.9% and 21.1%, respectively, compared to the tung oil-free adhesive controls. After 2 cycles of water soaking, the average of the soaked shear strength of glued maple specimens with WCM/tung oil adhesives was 3.49 MPa, representing a water resistance improvement of 46.6%, compared to the control value (2.38 MPa). For this study, the hot-press temperature (100-130 degrees C) was not critical for improving the water resistance of WCM or CSPI with tung oil. Optical microscopy images of the bondlines and interface showed that the improvement of adhesion strength and water resistance of cottonseed meal-based adhesives were due to the tung oil's prevention of the adhesives from diffusing away from the bond joints, while water soaking diffused the bondline, leading to weaker bond strength. The addition of tung oil varied from 0.05 to 1.0% (w/v), but we observed little influence on improving the adhesive strength values, therefore, we recommend the addition of 0.1% tung oil for economics and convenience. The results of this research provide useful information on cottonseed meals as one of renewable sources of wood adhesives.