Rheology of Natural Fibers Thermoplastic Compounds: Flow Length and Fiber Distribution

The presented study investigates the flow length and the corresponding fiber content distribution in the injection-moulded natural fiber reinforced thermoplastics and its relation to fiber type and processing parameters such as injection pressure, temperature, injection rate and mould tempering by increasing die temperature. In this research, polypropylene compounds with nominally 30 wt % hemp and sisal fibers are investigated. The influence of the injection pressure (500 and 1000 bar), melt temperature (180 degrees C, 200 degrees C, and 220 degrees C), and die temperature (23 degrees C and 80 degrees C) on the fiber content distribution all over the sample is investigated. An increasing linear trend of fiber content along the spiral length is observed as an evidence of a fiber/polymer multiflow system. A pattern for fiber content distribution with respect to the fiber length along the injected spiral can be distinguished, where the longer fibers are usually found at the end of the injected part and the shorter fibers remain near mould entrance point. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39861.