FRS—XRSA表征双轴取向PET的结晶度

AN IMPROVEMENT OF FRS-XRSA TO CHARACTERIZE THE CRYSTALLINITY OF BIAXIALLY ORIENTATED PET FILMS

全倒易空间Ｘ－射线散射理论分析（ＦＲＳ—ＸＲＳＡ）是研究与表征择优取向高聚物结晶度与取向分布的一种新方案，它可以解决粉沫法测定结晶度时取向试样难以消取向的困难，测定拉伸和回复过程中正在形变的取向试样的结晶度．在以前的工作中，对双轴取向的薄膜，仅进行了幅度β＝０°（ＭＤ）与９０°（ＴＤ）两个轴向，△α＝１０°的ＸＲＳ测定，这样推得的结晶度事实上是ＭＴ双轴ＸＲＳ的结晶度，即ＭＴ－ＸＲＳ结晶度Ｘ，这种处理包含着ＸＲＳ沿ＭＴ方向作均匀分布的近似．本文为了澄清这一问题，作了下述三点改进：第一，利用ＦＲＳ中ＸＲＳ的强度分布，内插计算αｉ；，βｉ＝０°～９０°，△βｉ＝１０°的ＸＲＳ，由此求得较符合理论要求的ＦＲＳ－ＸＲＳ结晶度Ｘ；第二，进行了ＦＲＳ－ＸＲＳ的极角因子ｃｏｓαｉ；校正；第三，合理地处理了当极角αｉ＝９０°时出现奇点的困难．结果较合理．同时亦获得了晶粒度在ＦＲＳ中的分布情况．

FRS-XRSA (Full -Reciprocal Space X-Ray Scattering Analysis) is a new procedure to characterize the crystallinity and orientation of various preferred orientation polymers. FRS-XRSA overcomes the difficulty of sample orientation when the crystallinity of orientated sample is measured by the powder method (PM).FRS-XRSA can also study the crystallinity of the deformed sample in the stretching and recovery processes. In our work, we measured XRS in two directions, i. e. latitude angle β =0° (MD) and 90 ° (TD) and △αi= 10 °. Thus MT-XRS crystallinity x was obtained' Here an approximation was assumed, i. e. the distribution of XRS from M to T direction was monotonous and smooth. But usUally that is impossible. Therefore, an improvement of FRS-XRSA was made as follows. First, according to the intensity distribution of FRS-XRS, the inserted XRS intensities in x, βi=0 ￣ 90 ° at △αi, △βi= 10 °, were obtained, then FRS-XRS crystallinity x,which accords with the theoritical basis, can be calculated. Second, the correction factor of polar angle cost, was considered in FRS-XRS. Third, the strange-point at α=0 ° where cosa is zero, was dealt with reasonably. The results are reasonable and satisfatory. Meanwhile, the distribution of the crystallite size in FRS was obtained.