Graphene type dependence of carbon nanotubes/graphene nanoplatelets polyurethane hybrid nanocomposites: Micromechanical modeling and mechanical properties

Abstract

Micromechanical modeling and mechanical properties of polyurethane (PU) hybrid nanocomposite foams with multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) were investigated by mean of tensile strength, hardness, impact strength and modified Halpin-Tsai equation. Three types of graphene, with varied flake sizes and specific surface areas (SSA), were utilized to study the effect of graphene types on the synergistic effect of MWCNT/GNP hybrid nanofillers. The results indicate a remarkable synergetic effect betweenMWCNTs and GNP-1.5 (1:1) with a flake size of 1.5 µm and a higher SSA (750 m 2 /g), which tensile strength of PU was improved by 43% as compared to 19% for PU/MWCNTs and 17% for PU/GNP-1.5 at 0.25 wt% nanofiller loadings. The synergy was successfully predicted using unit cell modeling, in which the calculated data agrees with the experimental results.

Analytical modeling and experimentally optimizing synergistic effect on thermal conductivity enhancement of polyurethane nanocomposites with hybrid carbon nanofillers

“…Before the PU synthesis, used MWCNTs were functionalized with hydrogen peroxide (H 2 O 2 ) to better interconnecting GNPs and formation of 3D structure in the polymer matrix, as reported elsewhere. [21,22,30] Different contents and ratios of MWCNTs and graphene were first mixed with polyol at 200 to 2000 rpm for 5 minutes using overhead stirrer equipment. Subsequently, the combination was ultrasonically dispersed for 5 minutes using ultrasonication and stirred again at 2000 rpm about 5 minutes.…”

“…[14][15][16][17][18] Recent experimental results indicate that combining two different nanocarbon fillers with varied sizes as hybrid fillers could lead to a synergistic effect because of a three-dimensional (3D) thermally conductive network formation, which exceeds the thermal properties of the individual graphene or carbon nanotubes filled nanocomposites. [17,[19][20][21][22][23][24][25][26][27] Yu et al [28] achieved a significant thermal conductivity enhancement for graphene and single-walled CNTs hybrid fillers with a weight ratio of 3:1. He et al [20] reported that the thermal conductivity was enhanced with 3D hybrid GNPs/CNTs inclusion in the polymer matrix at very low nanofiller loading.…”

Probabilistic model for flexural strength of carbon nanotube reinforced cement-based materials

“…Although the interfacial bond strength is very critical in determining the tensile/flexural strength [24], the existing models (e.g., Halpin-Tsai model [25] and Kelly-Tyson model [26]) typically assume a homogenous dispersion and perfect bond between CNTs and the hosting matrix [27]. Therefore, few researchers have modified the existing models by adding a multiplier of dispersion coefficient [28][29][30]. The different dispersion mechanisms of CNTs in cement matrix, however, limits the applicability of the existing models to CNT-cement composites.…”

Elastic modulus formulation of cementitious materials incorporating carbon nanotubes: Probabilistic approach

“…The conventional models, however, are unable to accurately predict the elastic modulus of nanocomposites in most cases [26,27], because these models disregard CNT dispersion and bonding characteristics within the hosting matrix. To overcome this, few researchers tried to modify the conventional models by including the CNT aggregation-related constants to fit the model to the experimental test data [28][29][30]. However, these modified models are empirical (i.e., without a physical meaning) and underestimate the elastic modulus of CNTreinforced nanocomposites below certain CNT concentrations [28].…”