Flow characteristics of polymer fibre tested by an expansion rheometer with pneumatic pipe and piston

摘要

An assembly measures the flow characteristics of a molten polymer under conditions of stretched flow using a high-tension crawl test (expansion rheometer). The required constant high level of tension is maintained by a pneumatic pipe. A polymer thread expansion rheometer stretches a sample polymer fibre at constant temperature and drawing force as a function of time. The information is used to calculate the elasticity and stationary expansion viscosity of the molten material. The required tension is generated by a piston (11) within a pneumatic pipe (17). The flow resistance is determined by the piston position within the pipe which has one or more slits (12) in the sidewall determining the flow resistance. The sample (3) is protected from a change in shape which would otherwise arise under the influence of gravity by a pipe (2). The pipe is closed at each end by discs (14, 15) over and under the sample. The disc over the sample is drawn via a thread (5) linked to the piston within the pneumatic tube.