Self-Healing Epoxy Coating Modified by Double-Walled Microcapsules Based Polyurea for Metallic Protection

The effectiveness of preploymer and 1,6-Hexamethylene diamine encapsulated by double-walled microcapsules based polyurea (PUA) was explored for healing the cracks generated in epoxy coatings. Double-walled microcapsules were systhesized by interfacial polymerization at the interface between the prepolymer droplets and the 1,6-Hexamethylene diamine droplets to form the polyurea shell. The effect of synthetic stirring speed on the morphology of the microcapsules was observed by scanning electronmicroscopy (SEM) and optical microscopy (OM). The chemical structure as well as the thermal properties and the core content were characterized by Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analyzer (TGA) respectively. Electrochemical impedance spectroscopy (EIS) studies of the artificial scratched area showed that the coating containing 2wt% and 5wt% microcapsules could effectively prevent further corrosion of the coating with high corrosion resistance efficiencies of 61.61% and 45.99% after immersing for 144h in seawater.

Thermal properties of α,ա- aminoalkylterephthalamides prepared from waste poly(ethyleneterephthalate) bottle and aliphatic diamines

Trimers and pentamers of α,ա- aminoalkylterephthalamides were prepared from aminolysis of waste poly(ethyleneterephthalate) (PET) bottle with tetramethylene diamine (TMDA) and hexamethylene diamine (HMDA). The thermal properties of these products determined by DSC and TG showed that the melting points were the temperatures at which physical melting process and chemical transamidation polymerization occured concurrently. This chemical reaction had converted trimers and pentamers into polymers, then at the higher temperature ranges, the observed decomposition temperatures were just specific for newly formed polyamides, not for initial trimers or pentamers. The application of thermogravimetric chamber as mini reactor is quite useful to investigate the heating conditions for solid-state polymerization of α,ա- aminoalkylterephthalamides.

Aminolysis of poly(ethylene terephthalate) waste bottle with tetra/hexamethylene diamine and characterization of alpha, ohmega-diamine products

The aminolysis of poly(ethylene terephthalate) (PET) waste bottle with excess amount of aliphatic diamines, such as tetramethylenediamine (TMDA) and hexamethylenediamine (HMDA) without catalyst has been carried out. Each trimers and pentamers in the obtained products were isolated and characterized by FTIR, NMR, HPLC methods. Although an excess of diamine was employed, longer blocks of oligomers were still formed as minor products.