Preparation And Application Of Sulfonated Polystyrene Nanoparticles By Soap Free Emulsion Polymerization

the emulsion formed by nanoparticles instead of traditional surfactants is of excellent storage stability.The emulsion is also known as Pickering emulsion.Soap free emulsion polymerization can produce monodisperse,adjustable size and surface functionalized nanoparticles,and potentially become an ideal approach to prepare Pickering emulsifiers.Although the preparation and application of Pickering emulsion have been widely reported to some extent,very few studies have concentrated on Pickering emulsion of asphalt which is not easy to de-emulsifier.In this thesis,the amphiphilic charged polystyrene nanoparticles(nano-SPS)were prepared by soap free emulsion polymerization of styrene(St)and sodium styrene sulfonate(NaSS)as monomers.Then the nano-SPS was used for paraffin emulsification,as well as raw asphalt and SBS modified asphalt emulsification.Finally,both paraffin and asphalt Pickering emulsions were employed to impregnate nonwovens.The soap free emulsion polymerization process,paraffin emulsification process and the microstructure&properties of immersed nonwovens were investigated respectively.The main findings and conclusions are arrived as follows:(1)The effective copolymerization of NaSS and St was achieved by soap free emulsion polymerization.When the dosage of NASS was 25%,the resultant nanoparticles had a good monodispersity with the particle size of about 40 nm,and its water contact angle at 60.4°.The nano-SPS showed good emulsifying ability to paraffin,raw asphalt and SBS modified asphalt.(2)The nano-SPS were used to emulsify paraffin and asphalt.The optimized formula of paraffin emulsion was that NaSS content was 25%,nano-SPS dosage was 1.5%,and paraffin-water volume ratio was 55/45.The optimal formulation of asphalt emulsion was that NaSS content was 25%,nano-SPS dosage was 2.5%,and asphalt-water mass ratio was 50/50.It was found that the all three Pickering emulsions were O/W type verified the dilution of the dispersed phase.(3)The paraffin microencapsulated nonwoven phase change material was obtained by impregnating viscose nonwovens with paraffin Pickering emulsion.After 20 heating and cooling cycles,it was found that when the dose of nano-SPS was the same,the greater the paraffin load,the higher the paraffin leakage rate;but under the same paraffin load,the increase of nano-SPS dose significantly reduced the paraffin leakage rate and undercooling.(4)Both raw and SBS modified asphalt Pickering emulsions had good impregnation effects on polyester nonwovens,and improved the tensile properties and impermeabilities to water and air of immersed polyester fabrics.SBS modified asphalt Pickering emulsion showed more uniform impregnation,and also had better tensile properties and better penetration resistance.