High performance coatings based on furan nanocomposites

RIVERO GUADALUPE; MANFREDI LILIANA

Blankenberge

Encuentro; Annual Meeting of the Belgian Polymer Group (BPG 2012); 2012

This work involves the development of polymeric materials derived from natural resources for their potential use as coatings for metal substrates. Furanic resins are proposed as possible alternatives to phenolic resins while maintaining their excellent chemical and thermal properties as well. The replacement of the toxic formaldehyde in the phenolic resin formulation and the use of furfural instead of it leads to a double benefit. While formaldehyde is a petroleum derivative and a dangerous pollutant, furfural can be easily obtained from agricultural wastes containing pentoses and it is harmless for the ozone layer. Thus, an additional valorization of biomass resources is profited. However, an exhaustive analysis of the furan resins performance is required to evaluate them as alternative materials. Besides, in the last decades, the addition of nanoparticles to polymeric matrix was reported to improve several properties (mechanical, thermal, anticorrosive, tribological, etc).1-3 However, the nanoparticles dispersion analysis as essential as the study of their influence on the chemical structure, reaction mechanisms and polymer final properties. A furan resin was formulated with phenol and furfural, and three different nanocomposites were synthesized by the in-situ addition of 2% of natural and modified montmorillonite type clays. The organic modifiers were selected in order to have compatible functional groups with the polymer. The chemical reactions involved during polymerization and the curing kinetics were studied. The clay incorporation accelerated the prepolymer formation and modified the reaction mechanisms. A chemical characterization of the materials allowed correlating their structure with their final properties, taking into account the influence of the different clays. The chemical nature of the modifiers was shown to notably influence the materials structure 4,5. In addition, the potentiality of furan resins as phenolic resins replacement was evaluated by the analysis of their performance as coating for metal substrates. The experimental procedures were optimized to obtain good quality thin protective films by dipping (Figure). The nanomechanical and anti-scratch properties were studied as well as the corrosion resistance in a chemically aggressive environment. From the nanomechanical point of view, the furan resins were found to be comparable to phenolics, so they represent a perfectly feasible alternative regarding the elastic modulus, nano-hardness, deformation mechanisms, etc. On the other hand, the organic barrier afforded to the aluminum substrate enhances its natural protection against corrosion as the oxide formation could block the film pores or cracks generated by the polymer aging in a corrosive medium.