Preparation And Ultraviolet Resistance Aging Properties Of Transparent PC Composites

Polycarbonate（PC）has good comprehensive properties,however,its stress cracking,wear resistance and weatherability（especially ultraviolet aging resistance）are poor,which limits the practical application of PC.In view of the application requirements of automobile headlamp shade,LED packaging and window glass,a transparent,ultraviolet aging resistant and high hardness composite material was prepared by using inorganic nanoparticles modified polycarbonate.The properties of PC modified by nanoparticles were characterized,and the ultraviolet aging behavior of composites in natural environment was simulated.The effects of nanoparticles content,ultraviolet absorbent and aging time on PC aging were studied.The main research contents and results are as follows:1.Orthogonal barium sulfate nanocrystals with good crystallinity and high reflectivity to ultraviolet light were prepared.The obtained nano-barium sulfate particles were spherical with regular and uniform shape,and the average particle size was between 100-200 nm.2.PC/BaSO₄ composites were prepared and their properties were characterized.The results showed that the content of nano-barium sulfate had little effect on the tensile strength and impact strength of PC/BaSO₄ composites.When the content of nano-barium sulfate was more than 0.3%,the hardness of the composites increased with the increase of the content of nano-barium sulfate.when nano-barium sulfate was added,the ultraviolet spectrum of the composites would be red-shifted and the transmittance would be affected to a certain extent（when the dosage was 0.3%,the transmittance was improved to some extent）.On this basis,adding ultraviolet absorbent can not prevent the degradation of PC,but can further improve the ultraviolet aging resistance of PC.When the content was 1.2%,the composite had the strongest anti-discoloration ability and anti-yellowing effect.At the same time,the transmittance of the composite was similar to that of PC,which achieved the goal of improving the ultraviolet aging resistance and maintaining a certain degree of transparency.3.PC/BaSO₄+SiO₂ composite films were prepared and their ultraviolet aging was studied.The results show that although the transmittance of PC/BaSO₄+SiO₂ composite films prepared by blending method decreases,their anti-ultraviolet aging properties were improved:the surface defects of the samples after ultraviolet aging were less,the anti-discoloration ability was stronger（the yellowing degree is lower）,and the change of transmittance during aging process is smaller.In the experiment,when the content of nano-mixed colloid（BaSO₄+SiO₂）was 7.5%,the yellowing degree was the lowest,the anti-discoloration ability was the strongest,and the transmittance was the best.The purpose of improving the ultraviolet aging resistance and keeping a certain transparency was achieved.In conclusion,adding nano-barium sulfate and nano-silica into PC matrix can improve the ultraviolet aging resistance of PC materials while maintaining a certain transparency.This kind of composite material may replace the traditional transparent material and be used in the fields of LED lampshade or automobile glass.