Polymers Subcommittee Agenda and Minutes

Polymers Subcommittee
Tuesday, October 17, 2000 at 10:30 am EST.
Chairman: Sanjeeva Murthy

Tom Blanton (Kodak), John Faber (ICDD), Ben Hsiao (SUNY- Stony Brook), Ron Jenkins (ICDD), Jim Kaduk (Amoco), Brian Landes (Dow), Sanjeeva Murthy (Honeywell)

Old Action Items
None. This was the first meeting of the subcommittee.

The members introduced themselves to the rest of the group with a brief description of their work and interests. The discussion quickly turned to the nature of the database, and this is summarized below. Members who can provide further details of their suggestions are shown in parenthesis.

The database will be helpful to users to identify the polymers (TB) as well as to enable them to see the diffraction pattern rather than just unit cell descriptions that we find in polymer handbooks (BH).

2-D images can be useful not just to display the patterns, but with appropriate tools can be used to generate various types (equatorial, meridional, radially averaged etc.) of scans with appropriate software (JF, SM). Archiving 2-D data is feasible since it is being done for instance in the form of pole figure plots (JF). We have a tentative contact for digitized pole figures: Thomas Blackford, Philips, Hamburg (JK). Many 2-D images are distorted, and therefore should we archive the corrected files rather than the raw data (JF, BH), or should we archive both (RJ).

Creating a 1-D database of radial scans will be most useful and hence should be attempted first (SM). We should first digitize the scans that are currently available in June Turley's book and elsewhere. We should collect and solicit new data in digital form both to add new polymers to the list as well as to replace the old ones in due time (SM, JK). We need a systematic approach to sample description because of issues such as orientation, crystallinity and polymorphism (BL). High quality powder diffraction patterns should be a starting point and this data set should be augmented later with more practical samples that are commonly seen in practice (extruded, molded, cast etc.) (BL) There should be samples with various types of orientation (TB). Should we include polymers at various degrees (e.g., drawn to various ratios) or just extreme orientations (BH)?

Because the polymer data are collected in many different ways (transmission, parafocus, diffractometer, 2-D detectors etc.), there should be a mechanism to accept these different types of data and convert into a standard format. We should make it as easy for the polymer community to submit the data. How do we accept the data from submitters? As Excel files? Some of the information we need along with the scan are: Name of the polymer and sample preparation, Instrument on which the data were collected, sample-to-detector distance (If 2-D), geometry - reflection or transmission and Wavelength (TB, BH, and BL).

We should adopt the CIF format (self-defining archival retrieval) that is currently used by the crystallographic community to archive and transfer ASCII files (JK). These can be done as PDF3 files that the ICDD has attempted to use in creating a clay database (JK). Do we display them as a function of 2q or Q (BH). We should also store calibration information/data along with data files (RJ).

The committee might consider soliciting proposals to undertake the task of converting printed scans into digitized scans (JK, TB).

Action Items
In six-eight weeks, members will submit a few scans in the format of their choice to John Faber.
BL - Polypropylene etc.
BH -?
SM - polyimides or LC polymers
TB - Already sent four files to ICDD

John Faber will use these data to create a test database for distribution to the committee members in about eight-ten weeks.

Meeting was adjourned agreeing to meet after John Faber distributes the files to the committee members.