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Melt flow rate testing of moisture sensitive plastics.

Rides, M; Allen, C R G; Omloo, H*; Nakayama, K*; Cancelli, G* (2008) Melt flow rate testing of moisture sensitive plastics. In: Proceedings of the Polymer Processing Society 24th Annual Meeting - PPS-24, 15-19 June 2008, Salerno, Italy.

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The current melt flow rate method (ISO 1133) does not adequately cover the measurement of materials that degrade or further polymerise at the melt flow rate test conditions. Materials such as PET, PBT and PA containing absorbed water tend to degrade, sometimes rapidly, at processing temperatures. This will result in poor repeatability and reproducibility of melt flow rate results. The ISO Plastics Melt Rheology committee (TC61/SC5/WG 9) is currently developing a modified melt flow rate method for reliable measurement of moisture sensitive materials, e.g. PBT and PET, thereby providing an alternative to intrinsic viscosity measurements. The modified method controls more tightly the time-temperature history experienced by the material and thus the resultant variability in measured properties due to degradation. Results on a range of moisture sensitive materials are presented, demonstrating the effect of moisture content and temperature on measurements. Repeatability of measurements of melt flow rate were up to 10% (1 standard deviation). The results of an intercomparison are also presented. The need to tightly control the sample preparation (e.g. drying) and sample handing procedures is highlighted as being critical to reliable measurements of such materials.

Item Type: Conference or Workshop Item (UNSPECIFIED)
Keywords: plastics, melt flow rate, MVR, MFR, moisture sensitive polymers, rheology
Subjects: Advanced Materials
Advanced Materials > Polymer Rheology
Last Modified: 02 Feb 2018 13:15
URI: http://eprintspublications.npl.co.uk/id/eprint/4171

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