Theses and Dissertations

ORCID

https://orcid.org/0000-0001-5801-020X

Advisor

Kim, Yunsang

Committee Member

Street, Jason Tyler

Committee Member

Kirker, Grant

Committee Member

Mohammadabadi, Mostafa

Date of Degree

8-13-2024

Original embargo terms

Visible MSU Only 6 months

Document Type

Dissertation - Campus Access Only

Major

Forest Resources (Sustainable Bioproducts)

Degree Name

Doctor of Philosophy (Ph.D.)

College

College of Forest Resources

Department

Department of Sustainable Bioproducts

Abstract

Wood-based panel products (WBPs) are considered highly sustainable due to their carbon neutrality, low embodied energy, and ability to be produced from various low-grade wood species. However, WBPs exhibit limited resistance to biological degradation, which can deteriorate their mechanical performance and shorten their service life. Additionally, WBPs may not be fully compatible with traditional wood preservation chemicals. This dissertation demonstrated a facile method of synthesizing essential oil-based natural preservatives compatible with WBPs. Four essential oils (EOs), namely thymol (THY), trans-cinnamaldehyde (tCN), carvacrol (CRV), and eugenol (EUG), were complexed with beta-cyclodextrin (beta-CD) to form beta-CD-EOs inclusion complexes through a sonochemical process using a high-power ultrasonicator (750W). The sonochemical variables, such as a molar ratio between beta-CD and EO, ultrasonication power, and centrifugation speed and time, were optimized to improve the inclusion yield of EOs in the complex and facilitate the large-scale production of beta-CD-EOs. Attenuated Fourier transform infrared spectroscopy (AT-FTIR) and X-ray diffraction analysis confirmed the formation of inclusion complexes at the different production scales. The inclusion yield of EOs in the complexes was estimated by ultraviolet-visible spectrophotometry (UV-vis) as well as thermogravimetric analysis (TGA), which was capable of differentiating unreacted EOs and loosely encapsulated EO molecules from the estimation of the inclusion yield. Differential scanning calorimetry (DSC) revealed that beta-CD-tCN did not adversely affect the curing properties of polymeric methylene diisocyanate (pMDI) used as a glue for plywood. The influence of beta-CD-tCN addition on the bonding strength of the wood composite was assessed by a lap shear strength test using 3-ply SYP plywood, following ASTM D906-20. Statistical analysis using the Tukey test at p<=0.05 indicated no significant difference between the bonding strength of pMDI and beta-CD-tCN as an additive, indicating that beta-CD-tCN could be successfully implemented in the manufacturing process of wood composite products as natural preservatives.

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