Interphase influences on the mechanical behavior of carbon nanotube–shape memory polymer nanocomposites: A micromechanical approach

2018 ◽  
Vol 30 (3) ◽  
pp. 463-478 ◽  
Author(s):  
MK Hassanzadeh-Aghdam ◽  
MJ Mahmoodi ◽  
R Ansari ◽  
A Darvizeh

The effects of interphase characteristics on the elastic behavior of randomly dispersed carbon nanotube–reinforced shape memory polymer nanocomposites are investigated using a three-dimensional unit cell–based micromechanical method. The interphase region is formed due to non-bonded van der Waals interaction between a carbon nanotube and a shape memory polymer. The influences of temperature, diameter, volume fraction, and arrangement type of carbon nanotubes within the matrix as well as two interphase factors, including adhesion exponent and thickness on the carbon nanotube/shape memory polymer nanocomposite’s longitudinal and transverse elastic moduli, are explored extensively. Moreover, the results are presented for the shape memory polymer nanocomposites containing randomly oriented carbon nanotubes. The obtained results clearly demonstrate that the interphase region plays a crucial role in the modeling of the carbon nanotube/shape memory polymer nanocomposite’s elastic moduli. It is observed that the nanocomposite’s elastic moduli remarkably increase with increasing interphase thickness or decreasing adhesion exponent. It is found that when the interphase is considered in the micromechanical simulation, the shape memory polymer nanocomposite’s elastic moduli non-linearly increase as the carbon nanotube diameter decreases. The predictions of the present micromechanical model are compared with those of other analytical methods and available experiments.

2018 ◽  
Vol 30 (1) ◽  
pp. 32-44 ◽  
Author(s):  
Mohammad Javad Mahmoodi ◽  
Mohammad Kazem Hassanzadeh-Aghdam ◽  
Reza Ansari

In this study, a unit cell–based micromechanical approach is proposed to analyze the coefficient of thermal expansion of shape memory polymer nanocomposites containing SiO2 nanoparticles. The interphase region created due to the interaction between the SiO2 nanoparticles and shape memory polymer is modeled as the third phase in the nanocomposite representative volume element. The influences of the temperature, volume fraction, and diameter of the SiO2 nanoparticles on the thermal expansion behavior of shape memory polymer nanocomposite are explored. It is observed that the coefficient of thermal expansion of shape memory polymer nanocomposite decreases with the increase in the volume fraction up to 12%. Also, the results reveal that with the increase in temperature, the shape memory polymer nanocomposite coefficient of thermal expansion linearly increases. The role of interphase region on the thermal expansion response of the shape memory polymer nanocomposite is found to be very important. In the presence of interphase, the reduction in nanoparticle diameter leads to lower coefficient of thermal expansion for shape memory polymer nanocomposite, while the variation of nanoparticles diameter does not affect the coefficient of thermal expansion in the absence of interphase. Based on the simulation results, the shape memory polymer nanocomposite coefficient of thermal expansion decreases as the interphase thickness increases. In addition, the contribution of interphase coefficient of thermal expansion to the shape memory polymer nanocomposite coefficient of thermal expansion is more significant than that of interphase elastic modulus.


2017 ◽  
Vol 51 (20) ◽  
pp. 2899-2912 ◽  
Author(s):  
MK Hassanzadeh-Aghdam ◽  
R Ansari ◽  
A Darvizeh

A comprehensive investigation is carried out into the elastic behavior of carbon nanotube-reinforced polymer nanocomposites using two combined analytical micromechanical methods. A unit cell-based micromechanical method is developed to model the random distribution of carbon nanotubes within the polymer matrix. Also, the Eshelby method is used for modeling the random orientation state of carbon nanotubes within the matrix. Two fundamental aspects affecting the mechanical behavior of carbon nanotube/polymer nanocomposites, including the carbon nanotube waviness and the interphase formed due to the non-boned interaction between the carbon nanotube and the surrounding polymer, are considered in the unit cell method. Comparisons between the results of present method and experimental data reveal that for more realistic predictions, five important factors including, random orientation and random distribution of carbon nanotubes, interphase, waviness and transversely isotropic behavior of carbon nanotube should be considered in the modeling of carbon nanotube-reinforced polymer nanocomposites. The effects of volume fraction, number of waves and waviness factor of carbon nanotube as well as the type of random distribution of CNTs within the matrix on the elastic modulus of the polymer nanocomposites are studied.


Author(s):  
Reza Moheimani ◽  
M Hasansade

This paper describes a closed-form unit cell micromechanical model for estimating the effective thermal conductivities of unidirectional carbon nanotube reinforced polymer nanocomposites. The model incorporates the typically observed misalignment and curvature of carbon nanotubes into the polymer nanocomposites. Also, the interfacial thermal resistance between the carbon nanotube and the polymer matrix is considered in the nanocomposite simulation. The micromechanics model is seen to produce reasonable agreement with available experimental data for the effective thermal conductivities of polymer nanocomposites reinforced with different carbon nanotube volume fractions. The results indicate that the thermal conductivities are strongly dependent on the waviness wherein, even a slight change in the carbon nanotube curvature can induce a prominent change in the polymer nanocomposite thermal conducting behavior. In general, the carbon nanotube curvature improves the nanocomposite thermal conductivity in the transverse direction. However, using the straight carbon nanotubes leads to maximum levels of axial thermal conductivities. With the increase in carbon nanotube diameter, an enhancement in nanocomposite transverse thermal conductivity is observed. Also, the results of micromechanical simulation show that it is necessary to form a perfectly bonded interface if the full potential of carbon nanotube reinforcement is to be realized.


2012 ◽  
Vol 41 ◽  
pp. 1641-1646 ◽  
Author(s):  
Shahrul Azam Abdullah ◽  
Aidah Jumahat ◽  
Nik Rosli Abdullah ◽  
Lars Frormann

2019 ◽  
Vol 129 ◽  
pp. 80-98 ◽  
Author(s):  
Mohammad Kazem Hassanzadeh-Aghdam ◽  
Reza Ansari ◽  
Mohammad Javad Mahmoodi

2007 ◽  
Vol 81 (2) ◽  
pp. 176-184 ◽  
Author(s):  
Qing-Qing Ni ◽  
Chun-sheng Zhang ◽  
Yaqin Fu ◽  
Guangze Dai ◽  
Teruo Kimura

2018 ◽  
Vol 29 (11) ◽  
pp. 2392-2405 ◽  
Author(s):  
Mohammad Kazem Hassanzadeh-Aghdam ◽  
Mohammad Javad Mahmoodi

In this article, a unit cell micromechanics model is developed to predict the elastic properties of shape memory polymer nanocomposites containing silica (SiO2) nanoparticles. The model incorporates an interphase zone corresponding to a perturbed region of shape memory polymer matrix around SiO2 nanoparticles. It is found that the elastic properties of shape memory polymer nanocomposites are significantly sensitive to the temperature in the presence of interphase region. As the temperature increases, the shape memory polymer nanocomposite elastic modulus decreases, while the normalized elastic modulus nonlinearly rises. The results reveal that Poisson’s ratio decreases nonlinearly with the increase of temperature. The shape memory polymer nanocomposite mechanical properties are significantly influenced by the nanoparticle diameter in the presence of interphase region. Substantial improvement in normalized elastic modulus is observed with reducing the nanoparticle diameter. Also, a nonlinear decrease in Poisson’s ratio is found as the nanoparticle diameter decreases. Furthermore, the role of nanoparticle diameter becomes more prominent due to enhancement of temperature. The results indicate that with increasing SiO2 nanoparticles’ volume fraction, the elastic modulus of shape memory polymer nanocomposite nonlinearly rises, while Poisson’s ratio decreases. Finally, it is shown that the increase of interphase thickness leads to the enhancement of normalized elastic modulus of shape memory polymer nanocomposite.


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