Abstract
Natural fibers are often used as a form of continuous twisted yarn, which are suitable for reinforcement of fibrous composites. In the twisted yarn, we often encounter phenomenon called ‘migration’, such that single yarns (spun yarns) shift from outer layer to inner and vice versa. Thus, we first observed migration structure of ramie twisted yarn through an X-ray CT scanner. Results show that migration occurred irregularly in the yarn, so this phenomenon was simulated by Markov chain model. In addition, the effect of migration on tensile properties was clarified. Although Markov chain model is not necessarily enough in predicting the migration occurrence probability, this model can predict well the state probabilities which single yarns exist in each zone after twisting. Finally, we found two structural parameters of twisted yarns which can be correlated with tensile strength. First parameter, i.e. the number of migration existing in a twisted yarn, had a weak correlation, whereas second parameter, i.e. the number of single yarns causing migration, showed a stronger correlation.
