The reason why the hardness of the rubber produced by the open mixer is lower than that of the internal mixer

Is it caused by the rubber mixing method that the hardness of the rubber material produced by the open mixer is about 10 degrees lower than that produced by the internal mixer for the same formula?
It's a bit of a deal, but not so much, right? 10 degrees? See if there are any other issues. There is a difference between open refining and internal refining, but it won't be that big! Especially for the differences in mixing equipment, mixing methods, and mixing time, there must be differences between the opening mixer and the internal mixer for rubber mixing. The opening mixer takes a long time and the refueling method may lead to low hardness. The difference between first stage refueling and second stage refueling is quite significant~but the difference of 10 degrees is a bit too big!
The open mixer is a small open mixer used in experiments. I have never seen it before during internal mixing, and I don't think there should be such a big difference. However, my colleagues tested it with such a big difference. It must be related, mainly due to the degree of mixing! The difference is too big. Check the weighing equipment and eliminate these factors first. If the weighing is not accurate, this situation can sometimes have a misleading effect. Perhaps you waste a lot of filling agent when using the open mixer to mix rubber.

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