A Modified Technique for Measurement of Orientation from Polymer Surfaces by Attenuated Total Reflection IR Dichroism.
Abstract
For a sensitive measurement of surface molecular orientation by attenuated total reflection IR dichroism, a modified sample holder was developed utilizing a symmetrical, double-edged internal reflection crystal. This modified sample holder allows the sample to be rotated without the disassembling and reassembling operations which change the contact area between the polymer and the ATR crystal. Therefore, correction of the reflectivities to an internal standard absorption band which is insensitive to orientation is not necessary in this modified apparatus. This was tested on two types of polypropylene. Results with uniaxially drawn polypropylene show that the surface orientation is similar to the bulk, as expected. On the other hand, the orientation as measured by this technique was greater on the surface than in the core of an injection molded polypropylene plate, a tendency confirmed by birefringence. This technique can be used for estimating bulk orientation of a thick sample without sectioning when the surface has similar orientation to the bulk. In cases where the surface differs significantly in orientation from the bulk, our technique should provide a more surface-sensitive estimation than birefringence, since the surface probed is much thinner (only about 1 micron) in this technique. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1980
- Accession Number
- ADA092662
Entities
People
- C. S. P. Sung
Organizations
- Massachusetts Institute of Technology