Estudio Mecanico De Peliculas De Pet Metalizadas

Surface & Coatings Technology 204 (2009) 661–666

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Surface & Coatings Technology
j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / s u r f c o a t

Mechanical study of metallized polyethylene terephthalate (PET) films
Sandhya Gupta ⁎, Manasvi Dixit, Kananbala Sharma, N.S. Saxena ⁎
Semiconductor and Polymer ScienceLaboratory, Department of Physics, University of Rajasthan, Jaipur-302004, India

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Mechanical properties such as Young's modulus (Y), storage modulus (E′), glass transition temperature (Tg), tensile strength (σ), and yield strength (σy) of metallized polyethylene terephthalate (PET) films have been measured using Dynamic Mechanical Analyser (DMA).Commercially available PET film thickness of 20 μm has been used for metallization. Aluminium (Al) and lead (Pb) have been coated separately on PET films by vacuum thermal evaporation method to form metallized PET films. The Tg of Al-PET and Pb-PET films has been found to be 112.3 °C and 111.2 °C respectively whereas Tg of commercial PET film is 89.7 °C. The stress– strain curves of metallized PET films at roomtemperature and at different elevated temperatures have been taken which show significant temperature dependence. In particular, the yield strength shows a decrement with increasing temperature. © 2009 Elsevier B.V. All rights reserved.

Article history: Received 25 April 2009 Accepted in revised form 31 August 2009 Available online 13 September 2009 PACS: 61.05.cp 62.20.de 62.20.fg 68.37.Hk68.55.-a Keywords: Mechanical properties Glass transition Coatings Strength Dynamic Mechanical Analyser

1. Introduction Due to high mechanical strength, toughness and durability, biaxially oriented and heat stabilized PET films are widely used in variety of industrial applications. These include the insulation for electric motors, capacitors, wires and cables as well as the base material for audio,video and computer tapes. Most of these applications require a metallization of the polymer film. This is particularly true for thin films used as dielectrics in capacitors [1,2], substrate for flexible organic lightemitting devices (OLEDs) [3], flexible solar cells [4], in fabrication of reflectors [5–7], corrosion protective films [8] and base films for the new generation of magnetic recording media[9,10]. Substrate materials are essential and prerequisite for meeting cost, performance, reliability and manufacturing goals for flexible displays. The flexible OLEDs made on indium–tin–oxide (ITO)-coated PET substrate have been tested under different mechanical stresses and no significant deterioration in the device performance has been observed when they are flexed at various bending radii [11]. Theseflexible OLEDs have very short lifetimes because plastics exhibit low resistance to moisture and oxygen. It is known that most metals possess lower gas permeability than plastics by 6–8 orders of magnitude [12]. Therefore, a
⁎ Corresponding authors. Tel./fax: +91 141 2704056. E-mail addresses: 1982sanman@gmail.com (S. Gupta), n_s_saxena@rediffmail.com (N.S. Saxena). 0257-8972/$ – see front matter ©2009 Elsevier B.V. All rights reserved. doi:10.1016/j.surfcoat.2009.08.051

several micrometer thick metal layer can serve as a highly effective barrier to minimize the permeation of oxygen and moisture. For example aluminium coated PET foil has good mechanical flexibility and superior barrier properties. Packaging films are mostly metallized with aluminium in a thermal evaporation process. It isseen that lead coating on PET strips is relatively thin and enhances the durability of the material. When exposed to surroundings lead has the inherent property of corrosion resistance. Besides this, the lead coated material solder readily and have a variety of applications such as in roofing and flashing application [13]. The suitability of PET films for vacuum metallization is related to its...