TPU/Leu可剥离膜的防腐性能及扩散行为的分子动力学研究

Study on Corrosion Resistance of TPU/Leu Strippable Film and Molecular Dynamics Simulation of Diffusion Behavior

摘要:

制备了增容改性前后的热塑性聚氨酯(TPU)/亮氨酸(Leu)防腐蚀可剥离膜TPU/Leu-1、TPU/Leu-2、TPU/Leu-3，通过Tafel极化曲线、电化学阻抗谱(EIS)和耐盐水加速实验评价可剥离膜的防腐蚀性能，利用分子动力学(MD)模拟方法，从可剥离膜对腐蚀粒子向碳钢表面扩散的阻碍作用入手，对腐蚀粒子的扩散行为和3种TPU/Leu可剥离膜的防腐效果进行了研究。结果表明：加入增容剂KH-560、E44后，TPU和Leu的χ小于χc，且δ和CED增大。RDF结果表明可剥离膜组分与增容剂之间的作用力主要包括氢键作用和静电吸附，说明KH-560及E44对TPU/Leu可剥离膜具有显著的增容效果。TPU/Leu-1的腐蚀电位为-0.430V，而TPU/Leu-2和TPU/Leu-3分别升至-0.320V和-0.348V，说明改性后可剥离膜的耐腐蚀性有所提高。MD模拟扩散结果表明，添加增容剂后，自扩散性能及D均下降，且FFVH2O(TPU/Leu-2)＜FFVH2O(TPU/Leu-3)＜FFVH2O(TPU/Leu-1)，FFVCl-(TPU/Leu-2)＜FFVCl-(TPU/Leu-3)＜FFVCl-(TPU/Leu-1)，说明可剥离膜对扩散行为产生抑制，KH-560改性的TPU/Leu-2抑制效果最为明显。

Abstract:

Thermoplastic polyurethane (TPU)/leucine (Leu) anticorrosion strippable films TPU/Leu-1、TPU/Leu-2、TPU/Leu-3 before and after compatibilization modified were prepared. The anticorrosion resistance performance of films were investigated by salt water test, tafel polarization curve and electrochemical impedance spectroscopy(EIS). Proceed from the inhibition corrosion of films on the diffusion of corrosive particles to carbon steel surface, the diffusion behavior of corrosive particles and the anticorrosion action of three kinds of TPU/Leu anticorrosive strippable films were studied by molecular dynamics simulation method. The results showed that the χ of TPU and Leu was less than χc and the δ and CED increased after adding compatibilizer KH-560 and E44. RDF results showed that the interaction force between components of strippable films and compatibilizers mainly included hydrogen bonding and electrostatic adsorption. It indicated that KH-560 and E44 can play an important role in improving compatibility of TPU/Leu strippable films. The corrosion potential of TPU/Leu-1 was -0.430V, while corrosion potential values of TPU/Leu-2 and TPU/Leu-3 increased to -0.320V and -0.348V. It illustrated that the corrosion resistance of strippable films were improved after modification. The diffusion of MD simulation results showed that self diffusion performance and D declined adding compatibilizer. Meanwhile, FFVH2O(TPU/Leu-2)＜FFVH2O(TPU/Leu-3)＜FFVH2O(TPU/Leu-1), FFVCl-(TPU/Leu-2)＜FFVCl-(TPU/Leu-3)＜FFVCl-(TPU/Leu-1). The result showed description of strippable films inhibit the diffusion behavior, in which the inhibition effect of KH-560 modified TPU/Leu-2 was the most obvious.