Cutting halves can be a breeze on a table saw. The trick is turning the round pipe into something with a square section. The first step is to use a ruler, tape, or easiest, the pipe itself to set the fence of your table saw to the exact outside diameter of the pipe. Take some scrap 3/4" plywood and cut square pieces - two for each piece of pipe you are cutting. Using a hot glue gun, glue one of the blocks to the end of the pipe, fitting it perfectly onto the end. Then place the block and pipe on a flat surface and glue on the other block, using the surface to ensure exact alignment with the level plane. Now you have essentially turned a pipe into a square block of wood.
Set the saw blade height just slightly higher than the wall thickness of the PVC pipe and set the fence so blade is exactly centered on diameter of pipe (and width of wood blocks) All that is left is to turn on the saw and run the assembly through once and then flip it and run it through again. Since you are only cutting slightly into the wood, the glue and the block will maintain the structural integrity of the pipe until all the cutting is complete. Just knock the blocks off with a hammer and you will have two perfect half pipe sections. NOTE - knock sideways with hammer. Hot glue has a decent amount of tensile strength (pulling object away from glued surface) but not much sheer strength (hitting it sideways) The blocks should pop right off.