Polymer Safety Mixing

If incompatible resins are mixed, either intentionally or unintentionally, parallel reactions can occur that exponentially increase the rate of degradation of both materials. The table below summarizes a few known interactions to watch out for.

It is important to note that trace amounts of either component can cause a runaway reaction. It is recommended to never process these base materials on the same machine. If this is unavoidable, the processor should ensure that the screw is pulled and thoroughly cleaned prior to material change-over. Purging the material handling system and extruder with non-reactive resin (PE, PS, etc.) will also help to reduce risk. In some scenarios (notably Acetal with PVC) the reaction evolves highly volatile gases that are forced out of the nozzle. If the machine tip is frozen off the reaction builds pressure that can fracture the barrel or launch the hopper off of the machine.

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