(A)The problem with using wood in building construction, is its susceptibility to mold, fungi, and termite infestation, resulting in over $1B/year damage and heighten health concerns. (B) Currently used, unencapsulated biocides have the problem of readily leaching or evaporating out and thus being effective for relatively short periods of time. (C) There is a potential health concern due to uncontrolled release of biocide from treated wood composites. (D) There is a need for a biocide carrier system that will enable easy mixing of the active biocide within wood product material while protecting the biocide during the material processing. (E) To compensate for leaching issues or partial biocide decomposition during the wood product's processing, a superfluous amount of biocide is added. (A)The main goal of the project is the development of products/additives that prohibit mold growth, have low toxicity to humans and perform well over a long period of time. (B) This project develops biocide-impregnated nanomaterials for slow/controlled release of the biocide to be triggered by the presence of water, i.e. will release when moisture or dampness is present. (C) This project investigates methodologies of incorporation of biocide-impregnated nanomaterials into wood composites with the potential of using an overall lesser amount of biocide than if used pure biocide within the wood product (i.e. addresses item E above under Situation or Problem section). OBJECTIVES: The U. S. forest products industry had sales of $262B in 1997, two thirds being used for building construction. The use of wood for home construction is an effective, efficient, environmentally friendly, renewable construction material. A problem in using wood is its susceptibility to mold, fungi, and termite infestation, resulting in over $1B/year damage and heighten health concerns. The goal of this project is to develop broad-spectrum biocide-impregnated nanomaterials (termed NanoCides), and to incorporate them into various wood/ wood composite materials such as oriented strand board (OSB), medium density fiberboard (MDF), ceiling tile, etc. Commercially available biocides will be selected for impregnation in NanoCide for their ability to protect wood from decay fungi, mold, bacteria and termites. Wood preservatives differ from other biocides and agricultural pesticides because wood is usually expected to be resistant to biodeterioration for a far longer period than are most other natural products. Furthermore, wood is expected to resist deterioration caused by a great diversity of organisms, including fungi, and termites. A successful wood preservative is therefore one that is long lasting and has a wide spectrum of toxicity toward various unwanted organisms in a variety of products and environments. The NanoCide developed from this project is expected to fulfill all of these wood preservative criteria. The proposed use of inexpensive, naturally occurring nanotubes for encapsulating biocides and adding the encapsulated biocides to wood products is expected to greatly extend the efficacy duration times of commonly used biocides and to also potentially use less biocide. The inert nanotubes carrier is also expected to shelter the biocide until needed. The slow-release feature of the encapsulated biocide could minimize biocide volatilization concerns. APPROACH: The technical approach is the development of an effective, long lasting and environmentally benign biocide that can be easily and inexpensively incorporated into wood products. This approach is based on the encapsulation of biocides into inexpensive nanotubes (NanoCides) that will facilitate incorporation of heat labile biocides into wood composite materials, protect and keep biocide dormant until needed and release biocide at a controlled rate. The projects will initially focus on the development of NanoCide and incorporation of NanoCide into MDF wood products. During Phase I, the NanoCide loading levels required for MDF will be determined, biocide controlled-release experiments will be performed and the effective efficacy will be determined (i.e., biocide lifetime or efficacy duration, spectrum of biocide protection, etc.). Leaching tests and biological tests for each MDF/NanoCide composition will be performed. Variations in NanoCide preparation will be conducted in an attempt to adjust the rate of biocide release to desired levels and methodology for incorporating NanoCide into MDF will be developed.
