| With the development of sustainable economy,materials polluting the environment can be used less and less,and environmentally friendly materials are more and more popular.Waterborne polyurethane is an environmentally friendly material because water as a dispersion,which has low organic volatile matter(VOC),and the production cost of waterborne polyurethane is low,meanwhile it has the excellent properties of plastics and rubber.Therefore,the application of waterborne polyurethane is increasingly favored.However,because the surface energy of waterborne polyurethane is about 40 mJ/m2,it is a high surface energy material,which is limited in the application of low surface energy products.It is a hot research topic for researchers to reduce the surface energy of waterborne polyurethane and broad the application of waterborne polyurethane.In this paper,a series of low surface energy waterborne polyurethanes were synthesized,and the effects of polysiloxanes,blocking agents,small molecular hydrophobic segments and soft segment hydrophobic segments on the surface energy of aqueous polyurethanes were induction and discussed.In the first chapter,the surface energy and low surface energy of waterborne polyurethane and its application were introduced.The specific experiments,tests and discussion were introduced from the second chapter to the fifth chapter.All the work was summarized in the sixth chapter in this paper.In this paper,waterborne polyurethane is synthesized based on the main raw material that polyoxypropylene diol(PPG),isophorone diisocyanate(IPDI),dimethylolpropionic acid(DMPA),1,4-butanediol(BDO),triethylamine(TEA),Ethylenediamine(EDA),and different hydrophobic monomers.And laser particle size analyzer,infrared spectrometer,X-ray photoelectron spectroscopy(XPS),contact angle measuring instrument,thermogravimetric analyzer,The electronic tensile test machine,scanning electron microscope and other synthetic products were analyzed and characterized waterborne polyurethane,the relationship between the surface energy of waterborne polyurethane films and its surface was emphasized researched.The specific research contents are as follows:In the second chapter,a series of polysiloxane-based waterborne polyurethanes were prepared by introducing different amounts of polysiloxane into the waterborne polyurethane.The effect of polysiloxane on the surface energy of waterborne polyurethane was obtained by comparison.The infrared test and XPS results showed that the mobility of silicon groups in the process of waterborne polyurethane film formation was getting higher and higher,the water contact angle of the film increased to 102.3°,and the surface energy decreased to 17.8 mJ/m2.Improvemently,thermal decomposition performance was greatly improved,when the amount of silicone added is 3%,the tensile strength was increased to 30.1 MPa,which is 1.5 times that of the case where no polysiloxane is added.The third chapter studied the effect of hydrophobic alkane chains,which have been rarely studied on the surface energy of waterborne polyurethanes in recent year.The alkane chain monohydric alcohols of different lengths were grafted at the end of the waterborne polyurethane.The relationship between the surface energy of the waterborne polyurethane film and its surface was studied.The test results show that the longer the length of the alkane chain,the more the migration of C-C groups on the surface of the waterborne polyurethane film,the water contact angle increased to 100.0°,the surface energy was 26.6 mJ/m2,and the water absorption decreased from 19.3%to 12.6%.The fourth chapter is to further explore the effect of the hydroxy-terminated side alkane chain(glycerol monostearate(GMO))block on the surface energy of waterborne polyurethane film.From the infrared and XPS tests,the more the amount of GMO added,the more hydrophobic C-C groups on the surface of the waterborne polyurethane film increased from 76.4%to 90.2%,the water contact angle increased,and the surface energy decreased to 26.5 mJ/m2 scanning electron microscopy revealed that the surface of the waterborne polyurethane film was uneven,the water absorption rate was reduced to 7.14%,the thermal decomposition performance was greatly improved,but the mechanical properties were lowered.On the basis of the fourth chapter,the waterborne polyurethane with different structure was designed by changing the synthesis process.The difference of GMO in the dispersion of hard and soft segments of waterborne polyurethane was studied.The effect on the surface energy and mechanical properties of waterborne polyurethane was studied.The results show that when n(IPDI)/n(GMO)=1.2:1 was dispersed in the soft segment chain,the surface of the waterborne polyurethane film has the more C-C groups,the maximum water contact angle was 112.56°,and the surface energy was at least 21.0 mJ/m2,the water absorption rate was reduced to 7.7%.When n(IPDI)/n(GMO)=1.3:1 was dispersed in the soft segment chain,and the tensile strength was up to 28.4 MPa,which is 1.8 times that of GMO not dispersed in the soft polyurethane soft segment sample. |
