The effect of biaxial orientation and crystallinity on the long‐term creep behavior of poly(ethylene terephthalate) films below glass transition temperature

Çakmak, Mükerrem; Wang, Y. D.

doi:10.1002/app.1990.070410741

Cited by 15 publications

(5 citation statements)

References 24 publications

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“…Both PET and PEN could have less mobility in crystalline regions, and the amounts of amorphous parts are likely to influence the viscoelastic property such as creep. Cakmak and Wang25 presented that the increase of crystallinity and orientation of chains in the amorphous region results in a reduction in creep strains for PET. Crystallinity as well as chain orientation play an important role in the determination of the creep property.…”

Section: Resultssupporting

confidence: 61%

Creep and shrinkage behavior of improved ultrathin polymeric films

Higashioji

Bhushan

2002

J of Applied Polymer Sci

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Long-term creep-deformation and shrinkage characteristics of improved ultrathin polymeric films for magnetic tapes are presented. These films include poly-(ethylene terephthalate) (PET), poly(ethylene naphthalate) (PEN), and aromatic polyamide (ARAMID). PET film is currently the standard substrate used for magnetic tapes, and thinner tensilized-type PET, PEN, and ARAMID have recently been used as alternate substrates with improved material properties. The thickness of the films ranges from 6.2 to 4.8 m. More dimensional stability is required for advanced magnetic tapes, and the study of creep and shrinkage behavior is important for estimating the dimensional stability. Creep measurements were performed on all available substrates at 25, 40, and 55°C for 100 h. Based on these data, master curves were generated using time-temperature superposition to predict dimensional stability after several years. The amount of creep deformation is considerably smaller for ARAMID and tensilized-type PET than for PEN, although Standard PET shows the largest amount of creep. In addition, creep measurements under high humidity also show similar trends. Shrinkage measurements at 55°C for 100 h show that the shrinkage of ARAMID is lower than that of PET and PEN. The relationship between the polymeric structure and dimensional stability are also discussed. Based on the creep and shrinkage behavior, ARAMID and tensilized-type PET seem to be suitable for advanced magnetic tapes.

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Section: Resultssupporting

confidence: 61%

Creep and shrinkage behavior of improved ultrathin polymeric films

Higashioji

Bhushan

2002

J of Applied Polymer Sci

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“…Tensilized‐type PET films, including T‐PET and ST‐PET, contain more oriented chains than Standard PET, which effectively restrain the molecular deformation along the drawing direction. Cakmak and Wang16 suggested that the increase in crystallinity and orientation of chains in the amorphous region results in a reduction in creep strains for PET. At the same time, tensilization stores mechanical energy in the material as it increases the entropy and leaves residual stresses in the system.…”

Section: Resultsmentioning

confidence: 99%

Tensile and dynamic mechanical properties of improved ultrathin polymeric films

Bhushan

Higashioji

2001

J of Applied Polymer Sci

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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.

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“…Polymers are organic materials that exhibit so-called viscoelastic properties, and which are usually brought out of thermodynamic equilibrium when cooled to below their glass transition temperature. The resulting time dependent phenomena have been particularly studied in the case of biaxially stretched PET films [171,172]. Polymers are also permeable to small molecules, which may lead to physical swelling phenomena, hence, to changes in stress state.…”

Section: Stress Optimization During Conversion Operationsmentioning

confidence: 99%

Durability of nanosized oxygen-barrier coatings on polymers

Leterrier

2003

Progress in Materials Science

472

341

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Research on silicon oxide thin films developed as gas-barrier protection for polymer-based components is reviewed, with attention paid to the relations between (i) coating defects, cohesive strength and internal stress state, and (ii) interfacial interactions and related adhesion to the substrate. The deposition process of the oxide from a vapor or a plasma phase leads in both cases to the formation of covalent bonds between the two materials, with high adhesion levels. The oxide coating contains nanoscopic defects and microscopic flaws, and their respective effect on the barrier performance and mechanical resistance of the coating is analyzed. Potential improvements are discussed, including the control of internal stresses in the coating during deposition. Controlled levels of compressive internal stresses in the coating are beneficial to both the barrier performance and the mechanical reliability of the coated polymer. An optimal coating thickness, with low oxygen permeation and high cohesive strength, is determined from experimental and theoretical analyses of the failure mechanisms of the coating under mechanical load. These investigations are found relevant to tailor the interactions and stress state in the interfacial region, in order to improve the reliability of the coating/substrate assembly. #

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The effect of biaxial orientation and crystallinity on the long‐term creep behavior of poly(ethylene terephthalate) films below glass transition temperature

Cited by 15 publications

References 24 publications

Creep and shrinkage behavior of improved ultrathin polymeric films

Creep and shrinkage behavior of improved ultrathin polymeric films

Tensile and dynamic mechanical properties of improved ultrathin polymeric films

Durability of nanosized oxygen-barrier coatings on polymers

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