2. General: "Thermoplastic Polyolefins (TPOs) in Roofing Applications" - this is a very good short introductory article available on the SPRI website.
3. Building Codes: "R905.13 Thermoplastic Single-Ply Roofing" from the 2015 International Residential Code and "1507.13 Thermoplastic Single-Ply Roofing" from the 2015 International Building Code. Both available on the UpCodes website.
4. Chemical Compatibility of TPO: See this Chemical Resistance Guide for information about whether a substance will damage a TPO roof. The document is on the website of Roofing Products International.
5. Inspection of TPO Roof Systems: "TPO (Thermoplastic) Rooftop Guide/Inspection Checklist" is a handy two-page document put together by Carlisle Syntec Systems. It references Carlisle products, but it's broadly applicable to other TPO systems.
7. Technical: "Technical Advisory - TPO Single-Ply Roof Systems: Performance and Service Life" is an RCI, Inc. paper from 2016 presenting "a general overview of information regarding the performance of thermoplastic polyolefin (TPO) single-ply membranes, to summarize general information related to the evolution of TPO single-ply roof membranes, and to provide general information to assist individuals with reviewing in-place existing conditions of TPO roof membranes".
10. Testing: "Testing TPO (An unprecedented study shows surprising variations among TPO membranes" explores TPO performance issues. The article appeared in Professional Roofing magazine in 2015.
11. Manufacturers: For a list of TPO roofing manufacturers, see here.