Testing Sticky Samples with MFT: Procedures for Barrel Cleaning
Cleaning up thoroughly the barrel of a Melt Flow Tester (MFT) after each test is necessary in order to have repeatable and reproducible results. However, in case of sticky or quickly degrading samples, it can be a very time consuming operation and require significant physical efforts – if done with the traditional manual cleaning tools. The Integrated Barrel Cleaning Device for CEAST Melt Flow Testers (models MF20 and MF30), is an electrical device, battery-operated, based on a cleaning tool with rotating interchangeable head. It's supplied with a rigid head suitable for cotton patches, and metal brush heads. Manually activated by the operator, it allows a safe and effective cleaning operation. It stays mounted on the machine but swivels back when not in use. It also reduces the risk of contact with hot surfaces of the instrument, increasing operator's safety.
We were asked to test a series of highly sticky samples, including PA6 and PA10 with wood fibers, and other filled materials. We tested them with a CEAST MF20 equipped with integrated barrel cleaning device plus the standard manual cleaning tools. Cleaning the barrel with the traditional system (manually pushing up and down the cleaning rod with a cotton patch) proved very hard and required up to 20 minutes after each test. Using the integrated barrel cleaning device the physical effort was much lower, and a shiny inner barrel surface was obtained after 5 minutes. The recommended procedure for the most troublesome samples is as follows. Do a first rough pass with the integrated device using the rigid head and a cotton patch, in order to purge out any plug or bulky residual, and leave just a layer of sample on the inner surface of the barrel. Then put on the metal brush without cotton, and push it up and down (head rotation is given by the electrical motor). If needed, use the manual tool in between passes, in order to remove sample detached from the walls but still remaining inside. The finishing pass shall be done with the rigid head and cotton patch.
Flow properties of molten plastics are a critical characteristic requiring good knowledge and control. The Instron® Melt Flow Testers are specifically designed for easy and accurate measuring of the Melt Mass-Flow Rate (MFR) and the Melt Volume-Flow Rate (MVR). CEAST Melt Flow Testers range from systems that perform a simple manual test procedure to semi-automated testing systems performing multiple weight tests.
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