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Mechanically strong waterborne poly(urethane‐urea) films and nanocomposite films
Author(s) -
Špírková Milena,
Pavličević Jelena,
Aguilar Costumbre Yareni,
Hodan Jiří,
Urbanová Martina,
Krejčíková Sabina
Publication year - 2021
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.50011
Subject(s) - biuret test , isocyanate , nanocomposite , ultimate tensile strength , materials science , urea , chemical engineering , montmorillonite , polyurethane , polymer chemistry , aqueous solution , composite material , organic chemistry , chemistry , engineering
A series of transparent waterborne poly(urethane‐urea) (PUU) films and nanocomposite films were prepared using isocyanate excess (5–50 mol% excess relative to the hydroxyl groups) and omitting the common chain‐extension step in the acetone method of the preparation. The surplus isocyanate groups were converted into urea and eventually biuret linkages via the reaction with water during the last phase inversion step. Nanocomposites were prepared by the direct mixing of the PUU nanoparticles in water with aqueous nanosilica or montmorillonite powder followed by slow water evaporation. Variable urea/biuret content is responsible for substantially different tensile properties; the neat organic films show elongation‐at‐break values of 100%–1120%, tensile strength values of 0.07–22.1 MPa, and energy‐to‐break of 0.1–85 mJ × mm −3 . All of the materials can be potentially used as soft‐to‐hard topcoats, depending on the specific demands. The most promising materials are films prepared at 30 and particularly 40 mol% isocyanate excess.