Tensile and dynamic mechanical properties of improved ultrathin polymeric films

Abstract

ABSTRACT:Tensile and dynamic mechanical properties of improved ultrathin polymeric films for magnetic tapes are presented. These films include poly(ethylene terephthalate) or PET, poly(ethylene naphthalate) or PEN, and aromatic polyamide (ARAMID). PET film is currently the standard substrate used for magnetic tapes; thinner tensilized-type PET, PEN, and ARAMID were recently used as alternate substrates with improved material properties. The thickness of the films ranges from 6.2 to 4.8 m.Young's modulus of elasticity, F5 value, strain-at-yield, breaking strength, and strainat-break were obtained at low strain rates by using a tensile machine. Storage (or elastic) modulus, EЈ, and the loss tangent, tan ␦, which is a measurement of viscous energy dissipation, are measured by using a dynamic mechanical analyzer at temperature ranges of Ϫ50 to 150°C (for PET), and Ϫ50 to 210°C (for PEN and ARAMID), and at a frequency range of 0.016 to 29 Hz. Frequency-temperature superposition was used to predict the dynamic mechanical behavior of the films over a 28 decade frequency range. Results show that ARAMID and tensilized films tend to have higher strength and moduli than standard PET and PEN. The rates of decrease of storage modulus as a function of temperature are lower for PET films than those for PEN and ARAMID films. Storage modulus for PEN films are higher than that for PET films at high frequencies, but this relationship reverses at low frequencies. ARAMID has the highest modulus and strength among the films in this study. The relationship between polymeric structure and mechanical properties are also discussed.

Technique development and measurement of Poisson's ratio, lateral creep behavior, and thermal and hygroscopic expansion of individual layers in magnetic tapes

“…6.35 ME-MDV/S 4.7 T-PEN(2) 4.7 a T-PEN corresponds to the sample in Bhushan et al 7 T-PEN(2), T-PET(2), and T-PET(3) are new samples.…”

“…1,7,12 The glass-transition temperatures of the PET and PEN substrate are 70 -80 and 120°C, respectively. 7,12 Information about the specific chemistry of the materials used in the front coats and back coats was not available from the manufacturers. However, based on Bhushan, 1 the front coat may consist of a single magnetic layer, as in the cases of single-layer MP tapes.…”

“…16 The viscoelastic properties of PEN films at ambient temperatures are controlled by the ␤* process, that is, a secondary relaxation over 30 to 70°C. 7,17 All the substrate films used in this study were biaxially oriented, and were metastable in two respects. First, the percentage crystallinity of the film is much lower than the equilibrium crystalline content.…”

Lubrication of advanced metal evaporated tape using novel perfluoropolyether lubricants

“…However, the tape substrate is a PET polymer of which the glass transition temperature is about 80°C (Bhushan et al 2002). Thermal treatment at 150°C could change the polymer structure.…”

Vibration analysis of axially moving magnetic tape with comparisons to static and dynamic experimental results

“…In order to create a multi-terabyte capacity, cartridge manufacturers are increasing the areal data density as well as the volumetric density (Bhushan 1996(Bhushan , 2000. Increasing the areal density results in higher capacity for a given volume of tape by decreasing both the track pitch and the length of a bit.…”