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A study of the effect of the extrusion variables and screw design on the thermal and rheological characteristics of acetal and nylon 66
Author(s) -
Shah Pravin L.,
Steward Edward,
Yazbak Gene
Publication year - 1994
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760341505
Subject(s) - extrusion , rheology , materials science , plastics extrusion , composite material , polymer , extrusion moulding , reactive extrusion , viscosity , melt flow index , nylon 6 , copolymer
A detailed study of the effect of several extrusion variables was made on the rheological and thermal properties of Delrin II acetal homopolymer and Zytel 42 polyamide 66 materials. A 63.5 mm Davis Standard extruder was used to measure the effect of screw design, screw rpm, die and head pressure, and melt temperature on the rheology of acetal and nylon 66 resins. A single stage metering screw was used to determine the effect of screw geometry and viscous heating on the melt viscosity breakdown and the rate of degradation of each polymer. The melt temperature was measured in the melt stream in the channel and correlations are shown between ideal melt temperature predicted from the rheology data and the actual loss of properties of each polymer due to viscous heating. The paper also discusses how to measure the melt temperature accurately in extrusion, and to use it as a key indicator to optimize the extrusion process, and to control the rheology, thermal stability, and the molecular weight of a polymer during processing.