The Impact Of The Diol Structure On The Properties Of Waterborne Polyurethane

Waterborne polyurethane(WPU)is a kind of emulsion dispersion system,which mainly uses green solvent,i.e.,water,as disperse medium.Compared with traditional solvent based polyurethane,which uses organic solvent as the main disperse medium,WPU has the advantages of being environmentally friendly,safe and reliable,without any pollution to the environment.So that WPU has very broad application and development prospects.The over-all properties of WPU have important relationship with the structure and properties of the main soft segments of WPU,which constitutes WPU.Investigation into the relationship between the over-all properties of WPU and the soft segments of WPU systematically have great significance.Using different polyols as soft segment,isophorone diisocyanate as isocyanate feedstock,dihydroxymethyl propionic acid as hydrophilic chain extender,1,4-butanediol as small molecular chain extender,we synthesize 6 kinds of waterborne polyurethane dispersion.The obtained WPU dispersions and the WPU films were fully and systematically characterized by laser particle size analyzer,thermogravimetric analysis,atomic force microscope,infrared spectrum,etc.,The effects of direct chain,branched chain,polyether and polyester on WPU performance and structure were systematically compared.The following conclusions are drawn:(1)Neat polyester polyol based on the structure of WPU film has better water resistance,heat resistance and mechanical properties of the film surface morphology and more rough,the emulsion stability is relatively poor,and the emulsion particle size will bigger.(2)The same linear structure of polyester polyol is larger than that of polyether polyol synthesis of WPU film has better water resistance,heat resistance and mechanical properties of polyether synthesis of WPUD film with more smooth surfaces and the soft hard segment separation degree is higher,and emulsion stability of the former is relatively poor.(3)The soft segment with branched chain structure has a lower particle size,and its film has a relatively lower heat resistance and mechanical properties,but its film surface is relatively smooth.