Aminic epoxy resin hardeners as reactive solvents for conjugated polymers: polyaniline base/epoxy composites for anticorrosion coatings

The Effect of Conductive Polyaniline on the Anti-Fouling and Electromagnetic Properties of Polydimethylsiloxane Coatings

In this paper, four conductive polyaniline powders doped in hydrochloric acid, sulfuric acid, phosphoric acid, and sulfonic acid were selected and blended with polydimethylsiloxane to prepare coatings with an electromagnetic absorption effect and fouling desorption effect, respectively. A UV spectrophotometer was used to evaluate the settling rate of the powders. Fourier transform infrared spectrometry, laser confocal microscopy, and scanning electron microscopy were used to observe the morphology and structure of the powder and the coating. The interface properties of the coatings were characterized using a contact angle measurement, the mechanical properties of the coatings using a tensile test, and the electromagnetic properties of the powders and microwave absorption properties of the coatings using vector network analyzers. Meanwhile, the antifouling performance of the coatings was evaluated via the marine bacteria adhesion test and benthic diatom adhesion test, and the effect of conductive polyaniline on the antifouling performance of the coating was analyzed. The results show that adding polyaniline reduced the surface energy of the coating and increased the roughness, mechanical properties and anti-fouling properties of the coating. Moreover, adding appropriate polyaniline powder can enhance the electromagnetic wave loss of the coating. The followings values were recorded for a hydrochloric-acid-doped polyaniline coating: lowest surface energy of 17.17 mJ/m², maximum fracture strength of 0.95 MPa, maximum elongation of 155%, maximum bandwidth of 3.81 GHz, and peak of reflection loss of -23.15 dB. The bacterial detachment rate of the polydimethylsiloxane (PDMS) samples was only 30.37%. The bacterial adhesion rates of the composite coating containing hydrochloric-acid-doped polyaniline were 4.95% and 2.72% after rinsing and washing, respectively, and the desorption rate was 45.35%. The chlorophyll concentration values were 0.0057 mg/L and 0.0028 mg/L, respectively, and the desorption rate was 54.62%.

Study of Graphene Epoxy/Nanoplatelets Thin Films Subjected to Aging in Corrosive Environments

The corrosion of metallic devices and degradation of plastic materials are a cause of great concern for companies and countries’ economies; it is necessary to contrast these phenomena by studying innovative methodologies and techniques. A simple solution lies in the realization of materials that can resist corrosive environments and be used as coatings to prevent, or at least delay, deterioration. The purpose of this work was to study the behavior of an epoxy resin, in thin film form, exposed to corrosive chemicals. In particular, the samples were subjected to aging of 31 days in dilute sulfuric acid (H2SO4) and in an aqueous solution of potassium chloride (KCl). Subsequently, thin films of Epoxy/graphene nanoplatelets (GNP) composite material have been subjected to the same conditions: it was investigated how these samples respond to the corrosive environment. We found that the addition of carbonaceous nanofillers prolongs in time the ability of the material to resist the attack of chemical agents.

A review of advances in the preparation and application of polyaniline based thermoset blends and composites

For several decades, forming blend and composite of polyaniline (PANI) with insulating polymers has been a widely studied research area because of the potential applications of such blends, which have a unique combination of mechanical properties, the processability of conventional polymers and the electrical property of conducting polymers. The current review paper will emphasize PANI composites or blends with thermosetting polymer matrices. The enhanced electro-mechanical properties of the blends and composites depend on the uniform dispersion of the PANI particle in polymer matrix. Therefore, considerable studies have focused on improving the distribution of PANI particles within the thermoset matrices. In this review paper, all the parameters and conditions that influence the surface morphology and application of PANI thermoset blends and composites will be described systematically. Recent progress on PANI based thermoset system with multifunctional ternary composites research will be highlighted in this paper. Furthermore, encouraging applications of different PANI thermoset composites and blends are discussed, such as flame-retardant materials, lightning damage suppression, metal ion removal, anticorrosive coating, electromagnetic shielding, conductive adhesives, and sensing materials.

Effect of polyaniline-modified glass flakes on the corrosion protection properties of epoxy coatings

In this study, polyaniline (PANI) and different mass ratios of PANI/glass flake (PANI–GF, PGF) composites were prepared via in situ oxidative polymerization. The chemical structure of the composites was investigated via Fourier transform infrared spectroscopy and X-ray diffraction. PANI, GF, and PGF composites were added as fillers into epoxy coating and then applied on a steel substrate. The corrosion resistance of the coatings was evaluated through electrochemical impedance spectroscopy and salt spray test. The coatings added with PANI, GF, and PGF composites displayed improved corrosion resistance. The greatest improvement in corrosion resistance was exhibited by the coating loaded with PGF composites at a PANI/GF mass ratio of 2:1. This enhancement was attributed to the passivation ability of PANI and the penetration resistance of the GF in the coating. Moreover, PANI was coated uniformly on the GF surface, and the composites were uniformly dispersed in the epoxy resin.

Effect of Chitosan Loading on the Morphological, Thermal, and Mechanical Properties of Diglycidyl Ether of Bisphenol A/Hexamethylenediamine Epoxy System

The effect of chitosan filled diglycidyl ether of bisphenol A (DGEBA) epoxy system were investigated using the thermal, mechanical, and morphological properties. The mixing ratio of resin/hardener was kept constant while the chitosan of 1.0, 2.5, 5.0, 7.5, and 10 weight percentage (wt%) was incorporated into the system. The thermal stability and the transition behaviour of the chitosan filled epoxy system were analysed through a differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) while atomic force microscope (AFM) and scanning electron microscopy (SEM) were used to investigate the morphology. It was observed that the additive tends to agglomerate, with the formation of clear phase separation, when the chitosan content increases above 5 wt%. At lower chitosan loading (2.5 wt% and below), relatively uniform dispersion of the additive can be achieved. The thermal stability of the system increases with chitosan loading while the mechanical tensile strength is compromised.