Date of Award

Fall 12-17-2021

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Forest Resources

Advisor

Douglas J. Gardner

Second Committee Member

Yousoo Han

Third Committee Member

Anil Raj Kizha

Additional Committee Members

Shane R. O'Neill

Abstract

The overall objective of this study was to explore the potential of utilizing secondary processing mill residues generated in Maine (1.6 million tons annually) in Wood-Plastic Composites (WPCs). Attributable to the huge shipping costs for transporting wood flour over long distances, wood pellets are explored as alternative feedstock for WPCs manufacturing. The mill residues from four species based on their abundance and potential applicability for utilization in WPCs manufacturing were used to make the two different feedstocks. The properties of the wood flour and pellets were studied along with the comparison of the properties of polypropylene-based WPCs using both of these feedstocks separately. In addition to this, the Network Analyst tool in ArcGIS and Sensitivity analysis were used for the transportation cost analysis on shipping these materials via truck transportation. Lastly, SimaPro software was used for life-cycle assessment (LCA) analysis to analyze the potential environmental impacts of wood flour and pellet production utilizing the mill residues and then transporting them to WPC manufacturers.

On average, the conversion of residues to wood flour and then wood flour into pellets reduced the moisture content by 54% and 52% respectively and increased the bulk density by 119% and 276% respectively. The physical and mechanical properties of WPCs using wood flour or pellets separately mixed with polypropylene were similar for both controls and formulations using coupling agents. On average, the transportation costs of wood pellets via a truck were reduced by at least 25% compared to wood flour and up to 70% in other transportation mediums having a larger weight limit. Based on the LCA analysis of the case study, transportation had the highest impact on the environment in contrast to other input variables related to production. Likewise, for similar quantities, the production and shipping of wood pellets appears to be more environmentally friendly than wood flour. Effects of global warming potential (GWP) for one ton (characterization) and one truckload (normalization) was higher by 8% for wood flour as compared to the pellets.

It is expected that this study will ultimately encourage investors to establish an industry segment supplying raw materials for WPC production in ME and ensure the efficient outlet of mill residues. Furthermore, WPC manufacturers would be benefit from the minimization of the raw material transportation costs through the utilization of an alternative wood feedstock that would positively impact their overall production process.

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