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Study of micro and nano surface structures from UV irradiated urethane/urea elastomers

Paper ID Volume ID Publish Year Pages File Format Full-Text
14067 1072 2007 5 PDF Available
Title
Study of micro and nano surface structures from UV irradiated urethane/urea elastomers
Abstract

In this work we address new results obtained with a thin free standing flexible film (∼120 μm) of a urethane/urea copolymer related to the formation of micro and nano size structures [M.H. Godinho, A.C. Trindade, J.L. Figueirinhas, L.V. Melo, P. Brogueira, Synthetic Metals, 147(1-3), 209 (2004); M.H. Godinho, A.C. Trindade, J.L. Figueirinhas, L.V. Melo, P. Brogueira, Molecular Crystals and Liquid Crystals (2005)]. The copolymer was synthesized from a polypropylene oxide-based prepolymer with three isocyanate terminal groups (PU) and polybutadienediol (PBDO) with PBDO content of 40% wt. After casting and curing the film was cut into different samples and each exposed to UV radiation for different periods of time; 23, 25, 26, 31 and 49 h (λ = 254 nm) and later extracted with toluene and dried. The dried films were then studied by polarising optical microscopy (POM), small angle light scattering (SALS) and the surfaces exposed to UV radiation analyzed by means of atomic force microscopy (AFM). Before extraction with toluene a nanometer-flat surface, characterized by a mean roughness value Ra = 0.59 nm, was obtained. Depending on exposure time to UV radiation and after extraction with toluene a corrugated surface, with features μm-sized in all axes, resulting in an increase of the overall mean roughness value to Ra = 50.7 nm, starts to develop after 25 h of exposure time. This work gives evidence of the non-monotonous time behavior of the wrinkled surface growth that develops under the action of ultraviolet radiation. As the exposure time increases the free-standing films directly exposed surfaces show a decreasing density of the structures observed and an increasing characteristic peak-to-valley height. The peak-to-valley height measured for samples exposed for 23, 25, 26, 31 and 49 h, respectively 193, 383, 381, 1550 and 2039 nm and the corresponding mean roughness values are Ra = 50.7 nm, 105.4, 116.8, 438.3 and 515.4 nm, respectively. Between 26 and 31 h exposure time a leap in both values, peak-to-valley and Ra, was observed. The sudden increase in these values is correlated to fabrication of wrinkles by uniaxially stretching PU/PBDO elastomer films.

Keywords
Urethane/urea elastomers; UV radiation; Polybutadienediol
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Study of micro and nano surface structures from UV irradiated urethane/urea elastomers
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Publisher
Database: Elsevier - ScienceDirect
Journal: Biomolecular Engineering - Volume 24, Issue 1, February 2007, Pages 97–101
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us