Holding 6 Inch Dia Pvc Pipe

I need to turn some 2"-12" long PVC rings with a simple chamfer at each end and a couple of inner and outer groves near the ends. My raw material is 2 foot, schedule 35 PVC pipe, 6" from the local HW store. The stuff flexes too much when I hold it with 3 or 4 jaw chuck. It is like trying to hold a jelly doughnut. I don't have any other chuck available.

I was thinking of turning a fairly tight fitting wood or aluminum plug for the chuck end so it doesn't crush. Not sure what to do in...

Holding 6 Inch Dia Pvc Pipe