Preparation of Polyurethane Monolithic Resins and Modification with a Condensed Tannin-Yielding Self-Healing Property

Abstract

Resins of polyurethane were prepared from vegetable oils (crambe and castor) and modified by adding green corrosion inhibitor (condensed tannin). The oils were characterized by gas chromatography with flame-ionization detection (GC-FID), attenuated total reflectance Fourier transform infrared spectroscopy (FTIR-ATR) and thermogravimetric analysis (TGA). The reaction was monitored by characterizing the intermediate products (polyester and prepolymer). The polyester was characterized by solubility in methanol, acidity index, hydroxyl groups and FTIR-ATR, and the prepolymer was characterized by solid content, solvent content, isocyanate (NCO) groups and FTIR-ATR. The formation of PU resins was confirmed by FTIR-ATR and TGA, and the presence of tannin particles incorporated in the coating can be observed by optical microscopy (OM). The absence of the band attributed to NCO in FTIR-ATR spectra of the resins confirmed the complete reaction between polyester and prepolymer. The OM observation and a video demonstrate that Polyurethane (PU)-modified with condensed tannin resin presents self-healing effect, probably through the formation of new hydrogen bonds when in contact with deionized water. Therefore, these results open possibilities for new synthetic routes aiming at improving the very important self-healing property for protecting metals and their alloys against corrosion, extending significantly the metallic materials lifetime as previously demonstrated by our group.

Analysis of fabrics and metal threads from two Andalusian liturgical vestments from the seventeenth and eighteenth centuries: a multitechnical approach

“…The bands at 1713 cm −1 and at 1245 cm −1 were assigned to the asymmetric C O stretching [22,23] and to the C-O stretching vibrations [22]. The signal at 1097 cm −1 corresponded to C-O-H bending [23], and those at 1020 cm −1 to O C-O-C or secondary alcohols and at 973 cm −1 to C C stretching [22]. Other parts such as the green fabrics of the gallon (4) or the core of the new metal thread (5) were fabricated with cotton (Fig.…”

“…The stage in which the most weight loss occurred was between 390 and 470 °C. This loss was due to the degradation to breaking of the bonds within polyester [23].…”

Nonedible Vegetable Oil-Based Polyols in Anticorrosive and Antimicrobial Polyurethane Coatings

“…The improved crosslinking and adhesion on mild steel gave a better chemical resistance [ 132 ]. Recently, Benedetti et al claimed improved corrosion protection of aluminum alloy AA2024 by tannin-modified CO-based PU coating, which favor crosslinking due to a high number of -OH groups in the chemical structure [ 136 , 137 ].…”

Preparation and Characterization of Condensed Tannin Non-Isocyanate Polyurethane (NIPU) Rigid Foams by Ambient Temperature Blowing

“…Tannin, because of their distinct chemical properties, are classified into hydrolysable tannins and condensed or polyflavonoid tannins [1]. They are natural phenolic compounds, fairly ubiquitous in the vegetable world and commonly utilized as a starting materials in many fields, such as medicine [2,3], wastewater treatment [4][5][6], activated carbon [7,8], wood adhesives [9][10][11][12], fire resistance [13,14], coatings [15][16][17], etc. Among these applications, their use to prepare biobased foams for thermal and acoustic insulation and other applications has already attracted attention, especially in the case of condensed tannin [18][19][20].…”