Location: Commodity Utilization ResearchTitle: Effects of pH and storage time on the adhesive and rheological properties of cottonseed meal-based products
Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2016
Publication Date: 3/29/2016
Citation: He, Z., Chapital, D.C., Cheng, H.N. 2016. Effects of pH and storage time on the adhesive and rheological properties of cottonseed meal-based products. Journal of Applied Polymer Science. 13:43637. https://doi.org/10.1002/APP.43637.
Interpretive Summary: As synthetic adhesives are mostly derived from depleting petrochemical resources and have caused increasing environmental concern, natural product and byproduct derived adhesives have attracted much attention in last couple of decades. With this trend, our group has demonstrated that cottonseed meal-based products can be used as wood adhesives. In this study, we investigated the effects of pH and storage time on the dry and wet adhesive strengths, and rheological properties of three cottonseed meal-based products- cottonseed meal (CSM), water washed cottonseed meal (WCSM), and cottonseed protein isolate (CSPI). The general trend of the dry, wet, and soaked adhesive strength was in the order WCSM > CSPI > CSM. Per the observations in this work, the cheap WCSM was more feasible and operational than relatively expensive CSPI in purpose of wood bonding. The adhesive slurry of WCSM could be prepared at its optimal pH of 6.0, but it was also usable in the range from pH 4.5 to 9.0.
Technical Abstract: Adhesive bonding is a key factor for efficiently utilizing timber and other lignocellulosic resources. To increase the basic knowledge of cottonseed meal-based adhesives and optimize the operational parameters for practical applications, in this study, we investigated the effects of pH and storage time on the adhesive performance, water resistance, and rheological properties of cottonseed meal (CSM), water washed cottonseed meal (WCSM), and cottonseed protein isolate (CSPI). We found all products possessed the highest dry, wet, and soaked adhesive strengths with the adhesive slurries prepared at pH 6.0 in the tested range from pH 4.5 to 11.0. The effects of pH were smaller on WCSM than on CSM and CSPI slurries, suggesting that the WCSM slurries were useable in a wider pH range (i. e. pH 4.5 to 9.0). Storage time (up to 8 days) did not greatly impact the adhesive performance of WCSM slurries prepared at pH 6.0, 7.5, and 9.0, but slightly reduced the adhesive strength of CSPI slurries with the same pHs. The viscosity of WCSM slurries increased with storage over 8 days, but did not for CSPI slurries. Our observation in this work suggested that WCSM not only possessed better adhesive performance than CSM and CSPI, but also was more flexible in setting relevant operational parameters for practical applications.