Care should be taken to ensure that massive adapters or head gates are adequately heated before introducing nylon resins. The temperature profile shown in Table 3 is typical of a four zone extruder. Variation of the suggested temperature profile may be appropriate, depending on screw configuration, potential power limitations, and the need to match melt viscosities. To minimize polymer degradation, do not exceed the EVOH manufacturer's recommended maximum melt temperature. The trim should be protected from moisture or properly dried before extrusion.
Process regrind layers according to the EVOH manufacturer's recommendations.
Purging Purging the system should be done with HDPE, LDPE, or PP, not nylon. The high temperature must be selected to avoid degradation, evident by yellowness or gels. The resins have a low toxicity by ingestion and are neither a skin irritant nor a skin sensitizer. When overheated, decompositions with fume evolution may occur. As with most plastics, use local ventilation to avoid exposure to fumes that may irritate the eyes, nose, throat, and upper respiratory tract.