If all the ingredients for a chemical reaction are in place, something is bound to happen, however slowly. Which means that, unless you can completely remove one of the reagents, there no effective means of completely stopping a reaction. This rather casts doubt on the concept of a "safe barrel temperature" for injection moulding or extrusion. What you perceive as safe temperature is only that temperature where there is no perceptible effect for the residence time concerned. Increase the residence time, and that temperature may be no longer "safe". So if there are any interruptions to production which impact on residence time, turn the barrel temperature down.