Stress Transfer Efficiency in Composites

As already mentioned, CNT dispersion and stress transfer must all be optimized to reach maximum mechanical properties. One of the most challenging issues in polymer nanocomposites is the determination of the stress transfer efficiency through the interface between CNTs and polymer matrix. This is a prerequisite to take advantage of the extremely high modulus and strength of CNTs. In addition, the high aspect ratio of CNTs necessitates huge interfacial areas available for stress transfer compared to traditional micrometer-size fiber composites. 

According to Cui et al. [82], the stress transfer in double-walled CNTs from the outer to the iimer walls within polymer composites is poor, such that the inner walls are virtually unstressed during the tensile and compressive deformation. The implication of this finding is that a significant reduction in the effective modulus of the reinforcement in MWCNTs composites is expected. 

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