Research On The Synthesis,characterization And Corrosion Inhibition For ADC12 Aluminum Of Hyperbranched Polyols

Hyperbranched polyol has sphere-liked,compact spatial structure,so between the molecular chains cannot almost twine around each other,and its viscosity is small while the viscosity hardly changes with the increase of relative molecular mass.A large scale of hydroxyls presented in the molecule can easily react with carboxyl,isocyanate,acetic anhydride,etc.Moreover,it can interact with metal materials by electrostatic adsorption where it covers the surface of metal materials,thus showing the corrosion inhibition.In this work,a series of hyperbranched polyols were synthesized and characterized.The corrosion inhibition of hyperbranched polyols and their precursors to ADC12 aluminium alloy in 0.5 M of HCL aqueous solution was investigated by potentiodynamic polarization curve and electrochemical impedance spectroscopy.The principal contents are as follows:(1)Aliphatic hyperbranched polyols from the first generation(G1)to the fifth generation(G5)were synthesized by 2,2-dihydroxy propionic acid(DMPA)and trimethylolpropane(TMP)as precursors,and p-methylbenzenesulfonic acid(p-TSA)as catalyst.Acid-base titration,carbon nuclear magnetic resonance,fourier transform infrared spectroscopy,micro melting point apparatus,and thermogravimetric analysis were employed to investigate the acid value,hydroxyl value,melting point,and structure of aliphatic hyperbranched polyols.Results indicate that all of the acid value-time curves of aliphatic hyperbranched polyols from G1 to G5 show obviously change which acid value decreases dramatically within 30 minutes,decreases slowly after 30 minutes,and cannot almost change ultimately.Meanwhile,with the generation of hyperbranched polyol,the hydroxyl value decreases.Carbon nuclear magnetic resonance spectra demonstrate the increase of branching degree with the increase of the generation of hyperbranched polyol.Correspondingly,the branching degree of hyperbranched polyol from G1 to G5 is 0.32,0.36,0.45,0.47,and 0.53,respectively.Thermogravimetric analysis shows that all of G1 to G5 have a similar thermal stability including the decomposition starting at 300℃,and fully decomposition in the range of 420-450℃.(2)The corrosion inhibition of different generations of hyperbranched polyols and precursors to ADC12 aluminium alloy in 0.5 M HCl was investigated by electrochemical methods.Potentiodynamic polarization curves and electrochemical impedance spectra show that all of G1 to G5 have a certain inhibitive performance,while the inhibitive efficiency increases with the increase of concentration.In the same concentration,the inhibitive efficiency decreases with the increase of the generation of hyperbranched polyol.At the concentration of 1.5 g/L,the first generation shows the highest inhibitive efficiency up to 93.90%.However,the precursor DMPA presents a slight corrosive action.Though the precursor TMP shows a slight inhibitive action,the mixture with TMP and DMPA promotes the corrosive action.Additionally,the corrosive potential before and after adding corrosion inhibitor cannot change obviously,illuminating such a corrosion inhibitor is a kind of mixed corrosion inhibitor.