Preparation Of Porous Polystyrene Microspheres And Application As Optical Diffusers

In this paper,LED light diffusion materials are studied aiming at the application problem of glare hazard of LED lighting.The polymer composites with good optical performance are obtained by preparing different kinds of light diffusion agents and adjusting the preparation technology and formulation.In this paper,the styrene(St)was used as monomer;DVB was used as crosslinking agent;toluene,liquid paraffin and DBP were used as pore forming agent.The porous polystyrene microspheres with excellent dispersion,controllable particle size and specific surface area were prepared by emulsion polymerization.The influences of reaction parameters,such as concentration of DVB,reaction temperature and the speed of stirring on the microsphere morphology and particle size distribution were studied.Scanning electron microscopy(SEM),infrared spectroscopy(FTIR),specific surface area(BET)methods and the other were used to characterize the microspheres.Further,porous polystyrene microspheres with different specific surface areas were prepared by using different types of pore-forming agents and different amounts of pore-forming agents.Light diffusion plate(2 mm thick)was prepared by the porous polystyrene microspheres and polycarbonate(PC),which compounded with the porous polystyrene microspheres by the twin-screw extruder and the injection molding machine.Results are as follows:(1)The polystyrene microspheres were prepared by emulsion polymerization,and the effects of crosslinking agent,emulsifier,reaction temperature and the speed of stirring on the particle size of porous polystyrene microspheres were determined.The polystyrene microspheres with uniform particle size distribution were obtained,which were 0.5-1 ?m?2-3?m?5-7?m?10-12?m.The influence of particle size and mass fraction on the optical and mechanical properties of PC optical diffuser plate was investigated.The light transmittance of PC optical diffuser plate increased gradually with the increase of particle size of the microsphere,but decreased gradually with the increase of mass fraction of the microsphere,and the haze showed an opposite trend.(2)According to the principle of phase separation,the porous polystyrene microspheres were prepared.The toluene,dibutyl phthalate(DBP),mixture of toluene/liquid paraffin and DBP/liquid paraffin were used as the pore-forming agents,the effects of the types of pore-forming agents and the amount of pore-forming agents on the specific surface area of porous polystyrene microspheres were determined,and porous polystyrene microspheres with different specific surface areas were obtained.The light transmittance and haze of pure PC diffuser plate were 90.37%and 5.1%.When porous polystyrene microspheres with different specific surface areas were used as optical diffusers,with the inc,rease of the specific surface area of the porous polystyrene microspheres,the light transmittance of PC optical diffusers gradually decreased and the haze gradually increased.When the specific surface area of the porous polystyrene microsphere was 150-155m2/g,the light transmittance of PC optical diffuser plate was 83.7%,the haze was 90.3%,and the haze was improved by 85.2%.(3)The porous Si02/PS microspheres were prepared by seed emulsion polymerization.The influence of addition of hydrophobic SiO2 on the particle size of porous microspheres,and the influence of porous Si02/PS microspheres on the optical properties of PC optical diffusers were investigated.The FTIR analysis and X-ray energy spectrum analysis of the microspheres,which etched by HF acid before and after,showed that porous SiO2/PS microspheres were successfully prepared.After particle size analysis,the addition of hydrophobic nano-SiO2 increased the average particle size of the microspheres from 2.56?m to about 5.26?m.When the porous SiO2/PS microspheres were used as light diffuser,the light transmittance of PC light diffuser plate was 82.1%,and the haze was 98.4%.Compared with the porous PS microsphere under the same conditions,the light transmittance of PC light diffuser plate was reduced by only 1.1%,while the haze was improved by 8.7%.