The effect of polarity of extractives on the durability of wood

Abstract

Extractives are low molecular weight compounds and regarded as nonstructural wood constituents. These compounds are present in trees and can be extracted by organic solvents. Extractives consist of several classes of compounds that diversify the biological function of the tree. Fats are an energy source for the wood cells whereas terpenoids, resin acids, and phenolic substances protect the wood against microbial damage or insects. In this investigation, extractives from five softwoods and four hardwoods were separated into nonpolar and polar components. The softwoods used were southern yellow pine Pinus glabra (SYP), alaskan yellow cedar Callitropsis nootkanensis (AYC), eastern red cedar Juniperus virginiana (ERC), western juniper Juniperus occidentalis (WJ), and western red cedar Thuja plicata (WRC). The four hardwood species used were black locust Robinia pseudoacacia (BL), honey mesquite Prosopis glandulosa (HM), paulownia Paulownia tomentosa (PAW), and catalpa Catalpa (CAT). All these species except PAW and SYP are classified as durable/highly durable. The percentages of polar and nonpolar extractives for the softwoods are AYC 46 and 54, ERC 36 and 64, WJ 49 and 51, WRC 97 and 3, and, SYP 83 and 17. The percentages of polar and non-polar for hardwoods are BL 99 and 1, CAT 87 and 13, HM 99 and 1, and PAW 95 and 5. Literature ranks of durability of these woods in order from most to least were ERC > WJ > BL > HM > WRC > AYC > PAW < SYP < CAT. This ranking was derived based on weight loss from fungi and insect infection. Understanding of the role of extractives polarity on durability is important from the preservative and medicinal aspects. Analysis of the chemicals affecting the durability and mortality of wood will help in identifying chemicals for preservation of wood and those that have biological activity. Chemicals from nature will be environmentally friendly and cost effective.

Citation

Moore, Roderquita K.; Smaglick, Jonathan; Arellano-ruiz, Erick; Leitch, Michael; Mann, Doreen. 2015. The effect of polarity of extractives on the durability of wood. Proceedings of the 18th ISWFPC (International Symposium on Wood, Fiber, and Pulping. 4 p.