Thermoplastic membranes containing expandable graphite

1. A multi-layered thermoplastic membrane comprising:

i. a first polyolefin layer where the first polyolefin layer includes at least two sublayers that are formed by co-extrusion, and where at least one of the two sublayers formed by co-extrusion includes expandable graphite; and

ii. a second polyolefin layer, where the first and second polyolefin layers are laminated to one another.

2. The membrane of claim 1 , where the membrane further includes a reinforcing scrim.

3. The membrane of claim 1 , where the second layer includes at least two sub-layers that are formed by co-extrusion.

4. The membrane of claim 3 , where at least one of the two sublayers formed by co-extrusion includes the expandable graphite.

5. The membrane of claim 1 , where the at least one layer includes at least 5 parts by weight expandable graphite per 100 parts by weight of the thermoplastic polymer.

6. The membrane of claim 1 , where said multi-layered thermoplastic membrane meets the specifications of ASTM D-6878-03.

7. A multi-layered thermoplastic membrane comprising:

first and second polyolefin layers laminated to each other, where said first polyolefin layer includes at least two co-extruded sublayers, where the at least two co-extruded sublayers of said first polyolefin layer include a top co-extruded layer that is exposed and an internal co-extruded upper layer that forms a laminated surface with the second polyolefin layer, and where said internal co-extruded upper layer includes expandable graphite.

8. The membrane of claim 7 , where the at least one layer includes at least 3 percent by weight expandable graphite based on the entire weight of the layer.

9. The membrane of claim 7 , where said second polyolefin layer includes at least two co-extruded sublayers including a bottom co-extruded layer and an internal co-extruded lower layer that forms a laminated surface with the first polyolefin layer, where said internal co-extruded lower layer includes expandable graphite.

10. The membrane of claim 7 , where said top co-extruded layer is devoid of expandable graphite.

11. The membrane of claim 7 , where said tope co-extruded layer is substantially devoid of expandable graphite.

12. The membrane of claim 1 , where said first polyolefin layer and said second polyolefin layer include a polyolefin matrix.

13. The membrane of claim 7 , where said first polyolefin layer and said second polyolefin layer include a polyolefin matrix.

14. The membrane of claim 7 , where said multi-layered thermoplastic membrane meets the specifications of ASTM D-6878-03.