Hyperbranched polyurethane (HBPU)-urea and HBPU-imide coatings: Effect of chain extender and NCO/OH ratio on their properties |
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Authors: | Aswini K. Mishra Ramanuj Narayan K.V.S.N. Raju Tejraj M. Aminabhavi |
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Affiliation: | 1. Organic Coatings and Polymers Division, Indian Institute of Chemical Technology, Hyderabad 500 607, India;2. CSIR Emeritus Scientist, Sonia Education Trust''s College of Pharmacy, Dharwad 580 002, India |
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Abstract: | Effect of chain extender and NCO/OH ratio on the properties of hyperbranched polyurethane (HBPU)-urea and HBPU-imide coatings were examined. The NCO terminated pre-polymers were prepared by reacting the first (G1) and the second (G2) generation hyperbranched polyester polyols (HBP-G1 and HBP-G2) with excess diisocyanate. The excess NCO content of the prepolymer was reacted with different chain extenders viz., 3-aminopropyl triethoxysilane (APTES), pyromellitic dianhydride (PMDA) and N-hydroxyphthalimide (NHTM) to obtain HBPU-urea or HBPU-imide coatings. The structure–property relationships of the different coatings were investigated by FTIR peak deconvolution, and these data suggests the highest extent of hydrogen bonding interaction for PMDA-based coatings, which increases with increasing NCO/OH ratio. Film properties were evaluated by TGA, DMTA, UTM and contact angle measurements; these results were supported by FTIR deconvolution results. As per contact angle measurements, hydrophobicity of coatings increased by increasing NCO/OH ratio. The adhesive strength, abrasion resistance, alkali resistance, and gel content of the coatings were also evaluated. |
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Keywords: | Hyperbranched polyester Polyurethane coatings FTIR DMTA |
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