Natural Rubber replacing Polychloroprene?

Manufacturer: We are making some rubber products using Neoprene (Polychloroprene) as the base polymer. Due to the high cost of this rubber, we're thinking of adding NR to reduce the recipe cost. What is the maximum level of NR we could at?

John Woon: I presume the reason you are using polychloroprene is because we want to achieve good resistance to ozone attack coupled with good resistance to oil for which NR is not a good choice.

You should start by replacing polychloroprene with NR at 8% as a start and check the physical properties of the final cured rubber especially the tensile strength, tear strength and compression set, of course not forgetting the oil resistance and ozone resistance.

You should not exceed 20 - 25% because beyond this level, you would begin to observe a steady drop in oil and ozone resistance.