©USFS

Since the first utilization of timber as a structural material, man has

sought to extend the service life of wood by reducing moisture

sorption.• Biblical Times: Pitch

• Ancient Greece: Olive oil

• Roman Times: First use of petroleum treatments

Within the last century, petroleum products have dominated the wood

preservation industry’s moisture resistant treatments

• John Bethell (1804-1867)

• Full-Cell Process

• Creosote

• Pentachlorophenol

In the context of this work, water repellency is the primary mechanism

for increasing wood durabilityEuropean researchers are studying many natural

water-repellent treatments

• Linseed Oil

• Sunflower Oil

• Rapeseed Oil

• Enviromental Impact- life of the product within the environment

• Economic Impact- cost structure of the product and end-user pricing

The wood-products industry must develop ‘environmentally sensitive’

products to satisfy consumer demand and the increasing regulatory pressure

• Improve the moisture resistance of southern yellow pine

• Impregnate southern yellow pine (pinusspp.) with wood pyrolysis oil

• Determine differences between high and low pressure treatment

• Determine the minimum retention levels necessary for improved moisture resistance

Pyrolysis is a process where cellulosic biomass is heated in an oxygen-free environment:•Traditional

•Slow heat transfer, long residence time•High char and low gas production

•Fast•Fast heat transfer, short residence time•Low char and high gas production•Best suited for pyrolysis oil production

(Princeton University)

Characteristics:

Contains over 300 compounds•Two phased:

•Hydrophobic•Phenolics

•Hydrophilic•Hydroxyaldehydes•Hydroxyketones•Sugars•Carboxylic Acids

Wood pyrolysis oil:•Rich in hydrophobic phenolic compounds•Biocidal to wood-degrading fungi.

•Fungi requires moisture:•Wood is typically impervious to fungal

degradation below 30% MC

•Hydrophobic/biocidal compound: •economical and environmentally sustainable

treatment option

Pyrolysis Specifications:•Auger-style reactor•Juvenile pine- forest residue•Reaction temperatures: 400-540°C•Homogenized using methanol 50%v/v•Filtered 5x using #1 Whatman paper

Treatment Specifications:•Bethell full-cell process•Dilutions: 50, 40, 30, 20, 10, 5%v/v pyrolysis oil•1hr. vacuum 1hr. pressure

Research Methods: Water Repellency

High Pressure Soak Low-Pressure Soak

Impregnation methods •High Pressure: 27” Hg Vacuum : 8.5 atm Pressure•Low Pressure: 27” Hg Vacuum : 1 atm Pressure

Drying Vacuum Pressure Evaporation

Research Methods: Water Repellency

Materials:• Whole bio-oil• Southern Yellow Pine (1” x 1” cubes)

Methods:1. Conditioned to a stable moisture content2. Determine specific gravity

With increasing pyrolysis oil concentration, the size of diameter of saturated lumens increased

• Pyrolysis oil was successfully impregnated into Southern Yellow Pine using either high or low pressure methods

• In a vapor environment moisture resistant benefits to moisture sorption and tangential expansion plateaued at concentrations of 10%

• In a soak environment, benefits were directly related to the concentration of pyrolysis oil

• Leachability of the treatment from the substrate is the main drawback to this treatment option