A process produces a block of polyolefin material with uniform crosslinking, which may be uniform between and within polymer chains in the polyolefin material. Steps include: providing an oven; placing the block into the oven; preheating the block to a uniform temperature above the melting point; further heating the block to a temperature at least 30 degrees Centigrade above the melting point; cooling the block to room temperature under an inert gas; and removing oxidized material from surface of the block. Optional steps include: subjecting the block to radiation before placing the block into the oven; removing the gases from the oven on a continuous or stepwise basis; controlling the purge gas flow out of the oven; and determining a heating time period for the block by subjecting control blocks to the same process and analyzing them after various heating times.