Numerical simulation of the tensile modulus of nanoclay‐filled polymer composites

Abstract

A numerical simulation model that incorporates three phases, polymer matrix, interlayer, and clay platelet, was developed to predict the tensile modulus of nanoclay‐filled polymer composites. The interlayer was introduced to account for the fact that the mechanical properties of the polymer near the clay surface are different from those of the polymer matrix. The effects of the properties of interlayers, the structure of clay clusters, and platelet distributions upon the modulus of elasticity of the nanocomposites, were studied. The simulation results show that a decrease in the interlayer modulus, as well as an increase in the interlayer thickness, would decrease the modulus of the nanocomposites. Furthermore, it was found that the maximum strain, located in the interlayer near the end of the clay platelet, increases significantly with decreasing interlayer modulus. The effects of the distribution of clay platelets upon composite modulus were interpreted in terms of two parameters, platelet overlap length, and the lateral distance between platelets. Comparison of simulation results with experimental data from the literature has confirmed the reliability of the numerical simulation method used in the present study. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2391–2406, 2004

A simple micromechanical approach to predict mechanical behaviour of polypropylene/organoclay nanocomposites based on representative volume element (RVE)

“…Hence, the staggering factor evidently becomes less significant for intercalated nanocomposites. This finding is in good agreement with the previous numerical results [15], which indicates that the elastic moduli of nanocomposites could be affected not only by the staggering factor but also the lateral distance between aligned clay platelets.…”

“…In addition, based on the experimental data, the interphase modulus might be in the range of E m and 2E m but much closer to E m , which quite differs from the general assumption of E i =2E m employed in the previous literature for modelling nylon 6/ clay nanocomposites [20]. This result can be attributed to the addition of low molecular weight MAPP as the compatibiliser to reduce the interphase modulus since their short molecular chains are highly mobilised adjacent to clay platelet surfaces and interlayer areas [15]. More importantly, the higher MAPP content due to the negative matrix plasticisation effect [25,27,28] could further decrease the interphase modulus, thus damaging the modulus enhancement mechanism.…”

“…A two-dimensional numerical simulation was also successfully performed using FEA in well aligned RVE patterns [12,15], which provided a better agreement with the experimental data compared to the conventional Mori-Tanaka and Halpin-Tsai models. MD simulation, on the other hand, can predict more accurately the mechanical properties [16,17] down to the nanoscale level but might get constrained by the integrated large lengths and time scales in the structural analysis of nanocomposites when the scale-up scheme is implemented.…”

“…However, previous research [15,20] has shown that there might be a third constituent in between with different material properties, known as "interphase", which plays an essential role in the property enhancement of composites especially when the size of reinforced particles is in the order of nanometer. Consequently, it is worthwhile to understand the interphase effect on the overall effective mechanical properties of RVE models.…”

“…Due to the great dimensional variations between the continuous polymer matrix and clay platelets with different aspect ratios in the range of 10-1000, 2-D RVE models have been found to be sufficient since their cross section can give a good representation of clay platelets in a 3-D domain [12,15]. For simplicity, it can be assumed that clay platelets are unidirectionally well-aligned and uniformly dispersed into the polymer matrix.…”