Contact potential durability

Wood is the most commonly used fencing material, and is also, potentially, the most environmentally friendly choice. Unfortunately, most fencing is made from nondurable softwoods, and strong chemicals may have been used to preserve it (see pp.132-133). In fact, as fence panels are rarely in contact with the ground— which is where wood is most at risk from decay— a simple water-repellent stain should protect them. Fence posts are most at risk from decay at ground level, where wood, air, and soil meet. Posts made from oak or cedar are recommended for their natural durability (see alsop.l33). Concrete post bases extend the life of wooden posts and make them easier to replace. 

Epoxy resins are the most commonly used thermosets, used for durable and inert coatings, in laminates and various composite applications, as well as an adhesive. Epoxies have low vapour pressures, so the potential for respiratory exposure is very low, and hence they do not pose health hazard indoors. The potential for dermal (contact) exposure is, however, much greater than respiratory exposure, which should not be a problem at all for a finished construction indoors. It is a reaction product of epichlorohydrin and BPA, which are not carcinogenic or a ECD agent. 

A study was made of the effect of electrochemical potentials on the durability of double shear type samples consisting of 2 black filled NR and 3 metal discs alternately bonded together. Metals employed were carbon steel. Inconel, stainless steel, titanium and titanium alloy. The influence of dissimilar metals in contact, high cathodic potentials and elastomer strain was evaluated and the results discussed in terms of failure penetration depth. (Tenth Annual Meeting of the Adhesion Society Inc., Williamsburg, Virginia, USA, 22-27 Feb. 1987). 4 refs. 

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