Dynamic moduli and creep damping analysis of short carbon fiber reinforced polymer hybrid nanocomposite containing silica nanoparticle-on the nanoparticle size and volume fraction dependent aggregation

Abstract

A hierarchical micromechanical procedure in conjunction with the elastic-viscoelastic correspondence principle is presented to estimate the dynamic moduli and creep damping capacity of short carbon fiber (CF) reinforced polymer hybrid nanocomposite (HNC) containing silica nanoparticle (SNP). At First, an analytical expression is derived to extract the damping properties in the frequency domain associated with a power law creep-time model. Then, a third phase known as interphase whose properties vary gradually, is taken into account to model the SNP/polymer interactions. The polymer matrix and the interphase obey a viscoelastic constitutive law. The CF random orientation is involved in the analysis as well. The effects of various parameters, including the SNP content, aggregation state and size; the CF content; the interphase properties; and the loading frequency (LF) on the HNC elastic modulus, creep compliance, storage modulus, loss modulus, and hysteresis loop are examined. As a novel idea, the SNP aggregation state is considered to be dependent on the SNP volume fraction (SNPVF). The SNP size effect is speculated by a newly presented intuition-based idea validated by the molecular dynamics simulation. Acceptable agreements in comparison with experiments prove the accuracy of the proposed model in the case that the intensity of the SNP aggregation is dependent on the SNPVF. It is found that a threshold for the SNPVF value can be reported to improve the HNC effective properties that beyond it, they tend to degenerate. It is also revealed that the SNP aggregation effect on the loss modulus diminishes as the LF increases in the manner that no change occurs in the LFs beyond 1e7 Hz. Additionally, the HNC overall properties are greatly affected by the NP diameters less than 20 nm.