Factors Affecting the Mechanical Deterioration of Cellulose Insulation

The rate of mechanical deterioration of cellulose insulation is dependent on the conditions of its use. Those factors of major importance are the temperature applied and the presence of oxygen and moisture. Moisture even in small amounts greatly affects the mechanical stability of the cellulose insulation. In general, the mechanical life of the insulation is reduced by half for each doubling in water content. Deterioration promoted by oxidation is most effective at temperatures below 120 degrees centigrade and is accelerated by the presence of moisture. The rate of deterioration for substantially dry insulation at temperatures above 120 degrees centigrade is dependent upon its previous history. Intermittent exposure to high temperature effects are additive. The ``eight-degree-centigrade rule,´´ indicative that the rate of mechanical deterioration is doubled for each eight-degree-centigrade increase from a base temperature of 120 degrees centigrade or higher, applies most closely for practical use when the insulation under study has lost more than 50 per cent of its tensile strength.