Progress 09/01/20 to 04/30/22

Outputs
Target Audience:TDA's technology benefits both the forest industry (by utilizing a waste stream) and the polymer composite industry (by developing an inexpensive and effective fiber source for reinforced plastics). The functionalized wood flours will be suitable for use in existing composite manufacturing strategies, improving the mechanical properties that can be achieved through surface modification of the wood flour particles. The proof-of-concept Phase I project's target audience is the polymer composite industry to demonstrate the promise of this new fiber feedstock (surface modified wood flour). Polymer composite manufacturers are the key customer for our technology, who produce and sell reinforced polymer composites to a variety of industries, specifically producers of composite decking and lumber. Our functionalized wood flour has shown promising results by limiting moisture absorption, which would be a major breakthrough for use in this application. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? In the Phase I project, TDA successfully completed all tasks outlined in our proposal and demonstrated the ability to produce surface functionalized hydrophobic wood flours and used them to make composites with better moisture resistance. We prepared a variety of surface modified wood flours using both pine and maple. The surface modification agents were selected based on computational results that use solubility calculations to predict which compounds will best serve to improve the wood flour's incorporation into polyethylene. When we characterized these powders, we found that the hydrophobicity of the functionalized wood flour was substantially increased compared to untreated wood flour. We also prepared composites using low density polyethylene (LDPE) to investigate the impact of the surface modification agent and wood flour loading on the composite's properties. These materials had mechanical strength after functionalization that was similar to or greater than that of composites made with unfunctionalized wood flours, and the composites made with modified wood flours had better moisture resistance. We also performed a preliminary technoeconomic analysis that showed that we can produce functionalized wood flour without increasing the cost of the composite, because we eliminate the traditionally required additives.

Publications

Progress 09/01/20 to 08/31/21

Outputs
Target Audience:TDA's technology benefits both the forest industry (by utilizing a waste stream) and the polymer composite industry (by developing an inexpensive and effective fiber source for reinforced plastics). The functionalized wood flours will be suitable for use in existing composite manufacturing equipment, improving the mechanical properties that can be achieved through surface modification of the wood flour particles. The proof-of-concept Phase I project's target audience is the polymer composite industry, to whom we will demonstrate the promise of this new fiber feedstock (surface modified wood flour). These composites are used in a variety of industries, including composite decking and lumber. Our functionalized wood flour has shown promising results for limiting moisture absorption, a major breakthrough for use in this application. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The overall goal of this project is to functionalize the surface of wood flour (a term that is generally applied to wood particles smaller than 20 mesh) to improve its physical properties for use in composite materials. The majority of the issues with wood-polymer composites are derived from the hydrophilicity of the wood itself. This includes agglomeration of the wood flour when mixed into a hydrophobic polymer matrix as well as water absorption. Traditional solutions (such as incorporation of compatibilizers) do not solve all of these issues. While they may improve manufacturability, they do not reduce water absorption, which causes damaging expansion and contraction of the material, fungal growth, and generally ages the material prematurely. Thus, wood-polymer materials site must be coated with a protective water barrier that if scratched or cut will jeopardize the bulk material. As an alternative, TDA's approach is to chemically modify the surface of the wood flour itself, reducing its hydrophilicity and imparting improved physical properties for the final composite, such as improved moisture resistance and dispersion within the polymer matrix. We have prepared a variety of surface modified wood flours, using both pine and maple. The surface modification agents have been selected based on computational results that identify appropriate compounds that will improve the wood flour's incorporation into polyethylene. Characterization of these powders shows that the hydrophobicity of the functionalized wood flour is substantially increased compared to untreated wood flour. We have also prepared composites using low density polyethylene (LDPE) to investigate the impact of the surface modification agent and wood flour loading on the composite's properties. Our results show that we maintain similar mechanical strength after functionalization, while improving the moisture resistance of the composite. TDA has explored multiple surface modification agents to chemically modify the surface of wood flour to improve the compatibility between the wood's polar surface and the non-polar PE polymer matrix, as well as to improve the hydrophobicity of a filler, which is an important feature for reduction of the moisture absorption, volume swell, and delamination of a wood flour/LDPE composite. Characterization of the wood flour samples has included contact angle measurements to measure their hydrophobicity and elemental analysis of samples functionalized with halogen tagged molecules to measure the loading of these surface modification agents on the wood flour. These results indicate that we are able to tether our surface modification agent to the wood flour particles and that we improve the hydrophobicity. These samples were formed into composites and tested for mechanical properties and moisture absorbance. Our findings indicate that we are able to reduce moisture uptake by the composite material compared to composites prepared with untreated wood flour. There are many commercial applications for wood-polymer composite materials. We are currently focusing on the decking industry as a target commercial application for these materials. Composite decking uses wood flour as a filler, but current state of the art materials suffer from issues with moisture adsorption and retention, which reduce the lifetime of the product. It would be desirable to produce lumber that can be cut as desired and that would not be compromised by scratching of the waterproof coating during normal use. Our collaborator, Lignetics (Louisville, CO), believes such a product would be well received by the market.

Publications