Studies on Biobased Non-Isocyanate Polyurethane Coatings with Potential Corrosion Resistance

Abstract

This work deals with the development of non-isocyanate polyurethane (NIPU) composites with an aniline oligomer, viz., tetraniline (TANI) for corrosion-resistant coatings. Firstly, epoxidizedsoyabean oil was converted to carbonated oil by inserting CO2 under high temperature and pressure into the epoxy ring. Then, varying weights of oligoaniline—0.5, 1, 2 and 4 wt % (based on the weight of CSBO)—were added to CSBO and cured with tetraethylenepentamine (TEPA, 25 wt % based on CSBO) at 80 °C for 12–15 h. The effects of oligomer loading on the thermal, mechanical and surface wetting properties of the free standing films were studied. The ATR-FTIR spectra of the films exhibited peaks corresponding to the bis-carbamate linkages, confirming the formation of urethane linkages. TGA analysis showed that the addition of oligoaniline did not alter the initial degradation temperature much; however, the residue increased with increasing loading of tetraniline. Both tensile strength and elongation (at break) increased with increasing oligoaniline content. While the glass transition temperature of the films was observed at approximately room temperature, i.e., 20–30 °C, for all the compositions, the contact angles of the composites were found to be less than that of the bare NIPU films. However, all the compositions were hydrophobic, exhibiting contact angles in the 98–110° range. SEM analysis of the cross-sections of the films confirmed the uniform distribution of tetraniline particles and surface morphology showed that the roughness increased with the loading of tetraniline from 0.5 to 4%. MS panels coated with NIPU exhibited good barrier properties and as loading of TANI increased, the rate of corrosion decreased. Salt spray tests indicated that oligoaniline improved the adhesion of the coating to MS and corrosion resistance compared to the neat NIPU coating.

Study of Soybean Oil-Based Non-Isocyanate Polyurethane Films via a Solvent and Catalyst-Free Approach

“…In the ESBO spectra, the H–C=C peak at 3009 cm –1 disappeared, whereas a new peak related to the C–O–C bending around 844 cm –1 appeared, which suggested the conversion of the unsaturation from the vegetable oil into epoxy rings. 29 In the CSBO spectra, there was the appearance of a peak around 1800 cm –1 assigned to the C=O stretch from the cyclic carbonated group, along with the disappearance of the peak at 844 cm –1 . Also, the peak at around 1700 cm –1 has been attributed to the C=O stretch of the ester group.…”

“…For the case of SBO, a small peak at 3009 cm –1 could be observed assigned to the H–CC stretch. In the ESBO spectra, the H–CC peak at 3009 cm –1 disappeared, whereas a new peak related to the C–O–C bending around 844 cm –1 appeared, which suggested the conversion of the unsaturation from the vegetable oil into epoxy rings . In the CSBO spectra, there was the appearance of a peak around 1800 cm –1 assigned to the CO stretch from the cyclic carbonated group, along with the disappearance of the peak at 844 cm –1 .…”

Design, synthesis, and evaluation of high‐performing anticorrosive polyurethane coatings with inbuilt redoxable oligomeric aniline segments

“…To the best of our knowledge, there are no reports available on anticorrosive coating applications with bifunctional amine‐capped tetramer (DCTAni) or trimer (DCTA) incorporated into a simple polyurethane backbone system. Very recently, we have studied the anti‐corrosion performance of biobased non‐isocyanate polyurethane with amine‐capped tetramer (DCTAni) 41 . In this study, first, we have synthesized NH 2 /NH 2 capped aniline trimer (DCTA) and tetramer (DCTAni) by oxidative coupling.…”

“…Very recently, we have studied the anti-corrosion performance of biobased nonisocyanate polyurethane with amine-capped tetramer (DCTAni). 41 In this study, first, we have synthesized NH 2 /NH 2 capped aniline trimer (DCTA) and tetramer (DCTAni) by oxidative coupling. These oligomers are reversibly oxidizable and reducible with whose property, maximum anti-corrosion property is achieved.…”

Adhesion and tribological characteristics of modified polyurethane coating on composite substrate

“…Hydrophobic and superhydrophobic-modified PU coatings were developed by the researchers to better understand the failure behaviour and mechanism of PU coating when the coated panels were subjected to marine and atmospheric conditions [14,[23][24][25][26][27][28] Surface roughness and gloss studies are the important characteristics to study to understand the visual effects of the coatings [29]. As we know the tribology of polymers differs from metals in terms of normal load, sliding speed and temperature (polymer has low melting point compared to metals).…”