Dr. Donatien Pascal Kamdem

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Project Summary:

        The main objective of this project is to increase the utilization of eastern hardwood species that are currently available but underutilized. This goal will be achieved if appropriate technology is developed and available to increase the uses of eastern hardwood species in exterior applications through the use of environmental benign chemicals.  To date, antioxidants and copper based preservatives are being tested as alternatives to arsenic and chromium containing preservatives for protection against biological and physical degradation.  After six years of field testing, damage caused by decay fungi and weathering of copper amine treated hardwood are limited.  Another major trust of our research program is to look for viable methods to disposed preservatives treated wood that are retired from service with limited sign of degradation.  Landfill is one of the best alternatives for disposal.  Our goal is to recycle this valuable source of wood fibers and to use them as raw materials for wood fiber composites.  Thermoplastic and cement will be used to manufacture wood fiber thermoplastic and wood cement particleboards, and the properties compared to that of commercial source to evaluate the commercial feasibility of such project.  We will also evaluate the properties of paper made from recycled wood fibers.

Key Words:

hardwood, copper, preservatives, recycling, wood fiber thermoplastic, weathering, decay resistance, wood decay fungi, wood cement

Current Projects:

The main objectives of the proposed study are to:

1. Characterize the weathering of hardwood and softwood wood exposed in an artificial laboratory accelerated weathering tester QUV, which simulates the out-of-doors and indoor environmental conditions such as the ultraviolet light and different relative humidity's.   Fourier transforms infrared spectroscopy (FTIR), ultraviolet-visible spectrophotometer (UV-vis), contact angle, and color changes are used to monitor the surface modification created by the weathering.

2. Understand the mechanism of wood weathering and propose means and options to reduce the modification of the weathered wood in order to increase the service life of wood products.

3. Evaluate the influence of weathering on the biological degradation of wood products.

4. Wood contains several chromophoric functional groups, which make it a good light absorber.  The photo degradation process is initiated by the formation of free radicals and presumably with oxidation of phenolic hydroxyl groups of lignin and wood extractives (Hon 1981).  Lignin and extractives are known to be partially responsible for the water repellency of wood, while cellulose is known for its high hydrophilic property.  Any modification in lignin and/or extractives of wood will alter the contact angle of the wood surface.

        The biodegradation of wood is considered to be due to the action of hydrogen peroxide released by a complex combination of biochemical processes.  The important factors for the generation of the hydrogen peroxide or hydro peroxides are the presence of free radicals, the pH and the concentration of some catalysts.  Generally, decay resistant wood species are rich in wood extractives, mostly flavonoids and stilbene.  These molecules are also known as antioxidants, because of their potential capacity to stabilize hydroxyl radicals generated or present in wood.  One of the important questions in wood protection is the importance of weathering on the decay susceptibility of wood.  Usually a laboratory test used to estimate decay resistance is conducted in the dark where the influence of light is negligible.

        The objective of this project is to determine the influence of weathering on the decay susceptibility of wood.  Two hardwood species; one specie known as decay resistant and the second known as non-durable were selected for this study.  The decay resistant specie that will be used for this study is rich in wood extractives (Padauk) and the non-durable specie is low in extractives content (soft maple). 

        To fully assess the role of wood extractives, the wood extractives from padauk will be used to treat aspen and evaluate their biological performance by conducting a laboratory soil block test after exposure to artificial weathering.

        About 75% of forestland in the northeastern part of the United States is composed of hardwood species, which are mainly used in furniture manufacturing.  The probable shortage of softwood combined with the goal of increasing the Michigan forest output may, one day lead to the exterior utilization of some hardwood species.  Given the hardwood lumber price, this alternative will be limited to the low grade and undesirable species for furniture manufacturing.  Several questions such as the natural durability of these species, the extension of their service life through preservative treatment and the impact of treatment on their physical and mechanical properties, need to be addressed.

        The objective of this project is the protection of hardwood species against decay fungi and insect damage in exterior applications.  Today, it is important to use biologically effective, cost effective, environmentally acceptable and low mammalian toxicity chemicals.

        Laboratory and field tests will be conducted to evaluate the biological performance of several formulations of the emerging wood preservatives on hardwood species according to the American Wood Preservers Association (AWPA 2000) and the American Society for Testing and Materials (ASTM 2000).  Naturally decay resistant species and southern pine will be included as reference species and used as background to estimate the index of decay. 

        The objective of this project is to evaluate the biological performance of several wood preservatives used to treat North American softwood and hardwood species and tropical hardwood species exposed under various tropical and temperate climate conditions.

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