Jason Stevens

Date of Award


Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)


Forest Resources


Douglas J. Gardner

Second Committee Member

David Neivandt

Third Committee Member

Yousoo Han


The objectives this research were to 1) examine the processing and properties of wollastonite as a filler in wood plastic composites, 2) determine effect of wollastonite on mechanical and physical properties of wood-plastic composites (WPCs), 3) to explore the possibility of the inclusion of wood ash in WPCs, 4) to determine the effects of wood ash on mechanical properties of WPCs, and 5) to evaluate the potential of wood ash as a filler/additive in WPCs. The wood plastic composites produced using wollastonite as a partial replacement for wood were extruded at loading levels of 4, 8 and 12% by weight, using polypropylene for the resin matrix. The wollastonite formulations were compared with a control formulation containing only wood flour and the polypropylene polymer. The experiments explored the processing and selected properties of the wollastonite-filled WPCs. The data suggested that wollastonite did not affect the abrasion resistance, slip resistance, or coefficient of thermal expansion of the composite. Mechanical properties were tested for the each wollastonite-filled WPC formulation. The wood plastic composite samples were evaluated for flexural, tensile, impact, and lineal burn rate properties. The samples were evaluated, and the data from each test were analyzed using an analysis of variance (ANOVA). The wollastonite-filled wood plastic composites performed similarly to the control formulation in each mechanical test. The wollastonite filler at higher loading levels reduced the lineal burn rate of the composite. The feasibility of including wood ash into wood plastic composites was investigated. Wood ash is currently an underutilized by-product of wood fired energy production, and has the potential to be used as a filler/additive in wood plastic composites. Wood ash was successfully extruded using polypropylene as a matrix and wood flour as filler and reinforcement. The wood ash was extruded in formulations of 2.5, 5, 7.5, and 10% loading by weight. An attempt to extrude at 12.5% loading proved unsuccessful. Mechanical and physical properties were tested for the wood ash and five (5) control formulations. The results indicate that the utilization of wood ash is possible as an additive in wood plastic composites. Wood ash increased several mechanical and physical properties when compared to the control formulations. Certain improvements in material properties including increased strength and stiffness were unexpected and suggest that wood ash has the potential to be included in WPCs.

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