小角光散射在线系统研究多相聚合物双螺杆挤出过程中的相尺寸--非相容PE/PA1010体系

利用可视化双螺杆挤出机———光散射在线采集与分析系统对不相容聚合物体系聚乙烯 尼龙 10 10(PE PA10 10 )双螺杆挤出过程进行了在线分析 .相尺寸由Debye理论中的相关距离ac,平均弦长L ,以及分散相平均直径D描述 ,给出了几种参数表征适用的范围 .由在线光散射计算出的平均弦长Lscatt、分散相平均粒径Dscatt与电镜照片计算出的平均弦长LSEM 、分散相平均粒径DSEM 作了比较 ,两者比较符合 .结果表明 ,分散相颗粒尺寸沿螺杆挤出方向逐渐变小 ;随着低组分含量 (PA10 10≤ 5 0 % )的增加 ,分散相颗粒尺寸变大 ,在组成比为 70 30和 6 0 4 0时出现双连续相

PHASE-SIZE ANALYSIS FOR MULTIPHASE POLYMER SYSTEMS DURING TWIN-SCREW EXTRUSION BY SMALL ANGLE LIGHT SCATTERING ONLINE MEASUREMENTS--POLYETHYLENE/POLYAMIDE IMMISCIBLE BLENDS

An online,non-destructive test system,based on small angle light scattering (SALS) measurements,was presented and applied to the phase-size investigation of polyethylene/polyamide 1010 (PE/PA1010) immiscible blends along the extruder during twin-screw extrusion.At the same time,some specimens were sampled online and analyzed by use of scanning electron microscopy (SEM).From SALS analysis,the phase size was characterized by the correlation length a c,average chord length L scatt and average diameter of dispersed phase D scatt according to the Debye theory.Because the correlation length a c is related to the average particle size and the volume fraction both,a c is only suitable for representing particle size among blends with the same composition.Average diameter of dispersed phase D scatt is suitable for representing the size of dispersed phase for discrete systems.Average chord length L scatt,however,could represent the phase size for discrete or co-continuous systems among blends with the same or different compositions.From SEM analysis the average chord length L SEM and average diameter of dispersed phase D SEM were also calculated according to their definition.The results of SALS and SEM are in good agreement,which show that SALS online system can be a powerful method to investigate the phase size during twin-screw extrusion.Both SALS and SEM show that the dispersed particle size becomes progressively smaller along the screw length.For the ultimate morphology of PE/PA1010 blends with different components (PA1010≤50%,volume fraction),the size of dispersed phases increases and the size of continuous phase decreases with the increase of the PA1010 component.At the composisions (PE/DA1010) of 60/40 and 70/30,co-continuous phases occur.