I routinely break down sheets of plex and similar plastics. In fact, I keep one of my TS55 fitted with a Festool Aluminum/Plastics saw blade cat 469 307. This is the current style with a 2.2mm kerf.
Appropriately setting the green plastic "presser foot" splinter guard is important. But, be cautious. The danger is that the presser foot is moving with the saw while in contact with the plastic, which can result in scratches. My practice is to protect the top side of the proposed with painters tape which has been tested and proven to peel away away cleanly after the cut is completed.
Also, my long experience is that the sacrificial surface under the plastic must not be soft and pliable. That defeats the purpose. Often the plex I buy has protective paper on both sides. I leave that in place on both sides, which save the time of applying painters tape. Below the plastic I use 19mm plywood as the sacrificial surface. So long as there is protective paper the underside will not be scratched by the plywood. If the lot of plex does not come with protective paper, I use fresh roll paper.
I also cut far deeper into the sacrificial surface than I do when cutting plywood or other wood-like material. I want the bottom of the tooth gullet to clear the underside of sheet plastic. The good news is such plywood need not be expensive, just stiff and yet easy on the blade. I do not recommend MDF, MDF-Light or MDO. I handle the sheets of plastic using vacuum cups. I do have a powerful vacuum hoist, but with 3mm and 6mm sheets up to 5' x 12' the weight is light enough hand pumped vacuum cups are strong enough.
You need to experiment with scrap to find the best speed of rotation for the TS55 and also the best speed to push the saw. What you want to avoid is melting the cut and the chips. Therefore often you need to push the saw faster than normal, but with the blade spinning slower than usual for plywood.
Many of my friends use a pressure beam saw for cutting plastic sheets. I found that to work well. The reason I do not do this on my beam saw or CNC router is the problem of mixing the plastic chips with the wood chips. To me it is more effective to keep a CT22 bag around just for the plastic chips. I set the CT22 to max and use my newest 36mm AS hose. Cutting plastic is not something you want to do using non-AS hose!
