MFI and Regrind...
This question arrived as a follow-up question to a recent post...
I am new to the business and an independent broker. In automobile parts (I deal with travel trailers, RV's, automotive and such) does MFI make a difference? Recycled or virgin? We are trying to cut costs, and it seems a lower MFI and recycled product is cheaper.
MFI is essentially a measurement of how much of a particular material flows through a capillary under a given load during the course of 10 minutes. The stresses and shear rates present in this test are not indicative of most plastics processes. If you want more comparative data you can acquire rheological data from the manufacturers... or request samples and actually preform some comparative rheological tests using your actual production equipment.
You always need to first determine whether the use of regrind poses a liability issue with your customers. You should determine the relative quality of the regrind. Depending on the application, you can choose from a wide range of Rheological, physical property, and performance testing methods.
Some related posts on rheology and physical properties: