The composition of magnetic recording tape is about 25 wt. % magnetic oxide particles, and 75 wt. % polymeric materials. With the exception of the recording properties of tape which are ascribable to the magnetic oxide particles, almost all of the other properties important to tape, such as aging, storage, tracking, etc., are ascribable to the chemical, physical, and mechanical properties of the polymeric materials.An experimental study was carried out to investigate the chemical behavior and stability (aging) of magnetic recording tapes exposed to the ambinent atmosphere consisting of oxygen, nitrogen, and humidity. This study showed that the primary mode of environmental degradation of tape results from a chemical reaction between the oxide's polymeric binder and atmospheric moisture, a chemical reaction called "hydrolysis". This reaction results in generation of sticky and gummy products which are infamous for tape sticktion, layer-to-layer adhesion, and increased tape friction and drag on recording heads. Temperature regulates the rates of hydrolysis, increasing the rate with increasing temperature. Oxygen was not found to degrade tapes, but does have an effect on the rates of hydrolysis.It was further found that tape hydrolysis reverses below a "neutral" relative humidity RH. Above this "neutral" RH, hydrolysis results in tape degradation, whereas below this RH, tape hydrolysis reverses causing restoration and rejuvenation. The ideal storage RH for our archival preservation of magnetic recording tape is at or below the "neutral" RH, which can be different for different tapes. This paper will discuss the experimental methods and results, and the important conclusions relative to tape storage, restoration, and handling. The aging behavior of magnetic recording tapes in hermetically sealed environments will also be discussed.

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Superposition of the loss tangent curves could be achieved for the β‐transition of a series of homologous epoxy resins. It was found that both a vertical and horizontal shift were necessary to achieve superposition when the curves were plotted as the logarithm of the loss tangent versus reciprocal absolute temperature. Resins from the diglycidyl ether of bisphenol A (DGEBA) were prepared with five different curing agents and their loss tangent curves measured on a free‐oscillation torsion pendulum (ca. 1 cps). The β transition is caused by DGEBA, which was found via molecular models to contain a mobile group. The intensity of the loss for three of the resins was found to be proportional to the concentration of DGEBA, molecular models revealing that no additional mobile groups were introduced by these curatives. The remaining two curing agents introduced mobile groups into their systems and for these two, no separate transitions were identified but the intensity of the DGEBA β transition was increased. This may be caused by a coupling of the DGEBA mobile groups through the flexibility of the curative‐introduced mobile groups.