Research On Micro-hot Embossing Of Polymer Self-cleaning Surface

The fouling of heat transfer equipment will result in the decrease of heat transfer efficiency and the increase of energy consumption,for this reason,self cleaning technology of heat exchanger fouling is a key technical problem to realize energy saving and emission reduction.Study on self cleaning bionic mechanism of lotus leaving out of the sludge without staining shows that the technical key to solve the problem of surface fouling is the formation of nano micro structured rough surface on the high energy surface in which similar bionic self-cleaning function can be obtained.The key technology to realize the self cleaning bionic target is fabrication and processing technology of nano micro structured rough self-cleaning surface.Based on the engineering background,in this paper,the hot embossing technology of self cleaning nano micro structured rough function surface was studied.The influencing rule of the processing parameters,the material properties of the substrate and the pattern of self cleaning nano micro structured function surface on the micro hot embossing process were studied by numerical simulation.The hot embossing mechanism of self cleaning nano micro structured function surface is revealed,and the key control parameters are clarified,which laid the scientific theoretical basis and technical support to transform finally to the whole process integrated control industrialized and scientific manufacturing in which quality was guaranteed by science and success was guaranteed by technology.The main results are as following:Based on four essential mechanical deformation characteristics of viscoelastic,yielding,softening and hardening and the characteristics of continuous solid phase evolution in the hot embossing of self cleaning nano micro structured function surface,and combined with experimental results of deformation stress and strain curves with large temperature range,a thermo mechanical large deformation viscoelastic plastic stress-strain constitutive model was developed to predict the effect of solid phase evolution.The influencing rule of the processing parameters,the material properties of the substrate and the pattern of self cleaning nano micro structured function surface on the micro hot embossing process were studied by numerical simulation,the results show that the elastic modulus,hot embossing temperature and pressure are the key control parameters affecting the quality of the products,the hot embossing pressure and deformation stress are negatively correlated with the hot embossing temperature and the cavity diameter of die.To increase the temperature of hot embossing temperature to above the glass transition temperature,and make substrate material in viscoelastic high elastic state,which make the hot embossing pressure and deformation stress be reduced to the minimum,and be helpful to release the molding products and avoid the fracture and deformation failure;It is found that the effect of substrate material on the hot embossing process is mainly reflected in the elastic modulus of substrate material,and the continuous phase evolution of the substrate material is the main controlling factor of sudden drop for elastic modulusComparative study on the hot embossing process of the cylinder model and the cone model show that the hot embossing pressure and deformation stress of the cone table model are obviously larger than that of the cylinder model,and increase with increasing of the diameter of model.