聚碳酸酯与苯乙烯-丙烯腈共聚物共混体系相容性及其对光学性能的影响

利用分子内链段排斥性相互作用理论研究了聚碳酸酯 (PC) 苯乙烯 丙烯腈共聚物 (SAN)共混体系中组份分子量及SAN共聚比例对体系相容性的影响规律 ,确定了获得均相的PC SAN共混体系的条件 ,考察了体系相容性与光学性能之间的关系 .通过实验获得了均相的PC SAN共混物 ;研究结果表明PC聚合度为 90、SAN聚合度为 3 0的PC SAN(S体积含量为 68%)体系共混比在 60∶40附近时体系的双折射能够实现补偿 ,紫外透光率达到 70 %.

THE STUDY OF MISCIBILITY AND OPTICAL PROPERTIES OF PC/SAN BINARY BLENDS

Polycarbonate(PC)is an excellent optical material with high transparency,but it also has high birefringence(Δ n 0=0 106)which has limited its application in computer use disk.It has been known that the birefringence of polymer blends may be improved by blending two polymers with opposite birefringence.If polycarbonate is mixed with a kind of polymer that has negative birefringence,for example polystyrene(Δ n 0= -0 10), it is possible to get a low birefringence polymer blend.Unfortunately,PC and PS is immiscible so that the blend is opaque due to high light scattering at the interface between them.To get a homogenous blend,a styrence copolymer was introduced.The miscibility of the binary polymer blend polycarbonate/styrene acrylonitrile coploymer was studied based on Flory Huggins theory in this paper.The effect of molecular weight and copolymer composition on the phase behavior and the dependence of transparency and birefringence of the blend on the blend composition were studied.A homogenous PC/SAN blend was prepared.It has been proved that the phase behavior of binary blend is determined by the combination of molecular weight and copolymer composititon.The condition of making a homogenous PC/SAN blend with low birefringence and transparency of 70% at 630?nm was found,if the polymeri\|zation degree of PC and SAN(S volume fraction is 60%) is 90 and 30,respectively.All polymers with required copolymer composition and different molecular weight in this work were prepared in our laboratory.A series of polymer blends with different blend ratio were made and their miscibility was judged by T g measurements using DSC technique,and the birefringence was measured by a polarizing microscope fitted with a Cenamen compensator.