PC/SAN共混体系微观结构与光学性能的关系及性能优化

Relationship Between Microstructure and Optical Properties of PC/SAN Blend and Property Optimization

以双酚A型聚碳酸酯（PC）为基体、苯乙烯-丙烯腈共聚物（SAN）为散射体,通过熔融共混法制备出聚碳酸酯基光散射材料,研究了SAN含量及密炼转速对共混物微观结构及光学性能的影响。结果表明,SAN含量的增加使散射体平均粒径呈增大趋势,且当SAN的质量分数小于25%时大部分粒子粒径小于1μm,在25%-35%之间时粒径变化较小,再增加则形成双连续相结构。透光率与雾度则随着粒径的变化呈先增大后保持平衡再下降的变化规律。而密炼转速的增大使小于1μm的散射粒子数目增多,透光率随之下降,雾度则几乎不变。通过Mie散射理论分析可以很好地解释上述变化规律。因此SAN的质量分数在25%-35%之间并以较低的转速进行加工可以得到最佳光散射性能的PC/SAN共混物。

High scattering composite sheets were prepared by melt blending processing,and bisphenol A polycarbonate（ PC） was treated as matrix,while poly-（ styrene-co-acrylonitri-le）（ SAN） was used as dispersed phase. The effect of SAN content and rotating speed of mixer rotors on the microstructure and optical properties was investigated. When the SAN mass fraction is less than 25%,the average particle diameter is increased,and more importantly,the amount of small particles（ d 〈1 μm） is significant decreased as increasing of the SAN mass fraction,then the particle size changes slightly in the SAN mass fraction range of 25% to 35%. Accordingly,both transmittance and haze increase with the increasing content of SAN and then reach an equilibrium value. Similarly,the increasing of small particles（ d〈 1μm） results in increase of the backward scattering,so the transmittance of PC / SAN blends decreases with increasing of rotating speeds of mixer rotors,but the balance of the scattering coefficients and the number concentration of particles eventually leads to the haze of blends almost remaining constant. All of these change rules can be well explained by the Mie scattering theory. In conclusion,the PC / SAN blends with best optical properties can be prepared at low rotation speed in the SAN mass fraction range from 25% to 35%.