| LED lighting device shows great strength compared with traditional lighting style,such as:energy saving,high efficiency,tiny size,long life,non-pollution,etc.Under the same brightness,energy consumption of LED lights is only 1/10 of that of incandescent lamp,and 1/4 of that of fluorescent lamp.LED lights have a lot of advantages in replacing fluorescent lamps and incandescent lights.However,the luminous intensity of LED lights is higher,and the light rays are more concentrated,it is necessary to choose a perfect light diffussion materials with great performance to make LED lighting uniformly.Therefore,it is of great practical value to study the preparation light difussion materials with high performance which can be applied in high power LED lighting systems.Silicone microspheres exhibit excellent thermal stability,good dimensional stability,otherwise,particle size and refractive index can be controlled by chemical reaction,so silicone particles have broad application prospects as a light diffusing agent used in light diffussion materials.In this thesis,monodisperse polysiloxane microspheres were prepared successfully by hydrolysis-condensation reaction from phenyltrimethoxysilane(PTMS)or methyltrimethoxysilane(MTMS).Scanning electron microscopy(SEM),thermogravimetric analyzer(TGA),infrared spectroscopy(FT-IR)methods and the other were used to characterize the microspheres.The influences of parameters,such as the concentration of monomer precursor,ammonia dosage,reaction temperature and the speed of stirring on the morphology and size distribution of particles were investigated.At the same time,copolymer microspheres with refractive index of 1.3851?1.5081 were prepared by MTMS and PTMS monomer.Light diffussion plate(2 mm thick)was prepared by the microspheres and epoxy resin(E51)or polycarbonate(PC).And the influence of doping radio,particle size and refractive index to transmittance and haze of the plates was discussed.Results are as follows:(1)Monomer concentration and ammonia concentration were the main factors that affecting the morphology of the microspheres.With the increasing of monomer concentration in the reaction system,the uniformity of particle size decreased,the average particle size of the microspheres increased gradually.The high concentration of monomer will lead to agglomeration.The average particle size of the microspheres decreased with the increasing of ammonia,when the pH was almost neutral,silicone monomer could not hydrolysis complete-ly,and the microspheres can not be a ball.When the pH was between 8 to 11 during the condensation,good dispersion microspheres can be observed.The growth process of PTMS microspheres was studied by seed method,it was found that a large number of nucleus were formed in a short time,and then the nucleus continued to grow,secondary nucleation process never existed in the whole process.(2)The results of light transmittance and haze of epoxy resin light diffussion material were analyzed.With increase of the addition concentration,and decrease of refractive index of silicone microspheres,light transmittance of light diffusion plate decreased,and haze increased.When the particle size was 1.05 um,and doping concentration was 0.1 phr,total light transmittance and haze of light scattering materials with the thickness of 2 mm was 83.6%and the haze was 95.5%.(3)The light diffusion properties of PC light diffusion materials were studied.The experimental date and theoretical simulation results were consistent.When the refractive index of the microspheres relative to the PC was 0.91 to 0.93,the contradiction between high transmittance and high haze can be resolved,and the high transmittance and high haze can be achieved.when the average diameter of micro spheres was 1.7 ?m(refractive index is 1.4580),and doping concentration was 0.4 phr,total light transmittance and haze of light scattering materials with the thickness of 2 mm was 87.9%and 98.5%respectively. |
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