A study on the synergetic effects of self/induced crystallization and nanoparticles on the mechanical properties of semi-crystalline polymer nanocomposites: experimental and analytical approaches

Abstract

This study investigates the effects of nanoparticle content, aggregation/agglomeration, polymer/particle interphase, and crystallinity on the mechanical properties of high-density polyethylene (HDPE) nanocomposites. Different samples of HDPE nanocomposites, containing 0.5, 0.75, and 2 wt.% of pure and surface-modified silica nanoparticles, were prepared by the melt-mixing method. The pure silica nanoparticles (PSN) and surface-modified silica (AMS) with (3-Aminopropyl) tri-ethoxy silane were characterized with field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FTIR) spectra.Differential scanning calorimeter (DSC) and X-ray diffraction (XRD) were used to estimate the crystallinity and crystal size of the samples. Finally, tensile testing was performed on the nanocomposites to establish the relationship between mechanical properties and nanoparticle loading, and surface modification. The results indicate that the crystallinity and elastic modulus of the nanocomposites increased with increasing nanoparticle content. Moreover, the Gutzow-Dobreva theory was used to determine the induced crystallinity. A mechanical model (Equivalent Box Model) was proposed to determine the crystalline, amorphous modulus, thickness and tensile modulus of the polymer/particle interphase region, which shows a decreasing trend with the nanoparticles content and indicates that this region is thicker for the HDPE/AMS relative to HDPE/PSN.

Isothermal crystallization kinetics of pure and surface‐modified silica/high‐density polyethylene nanocomposites

“…It is clear that the distance is the lowest for nanocomposite samples containing 0.75 wt% of PSN and AMS nanoparticles, suggesting that it is easier to obtain large crystals in these two samples. The same results were reported in our previous work for these samples, based on X‐ray diffraction analysis 27 …”

“…The obtained white turbid suspension, after 60 min of sonication, was centrifuged and the synthesized spherical silica nanoparticles were collected and washed several times with deionized water. To increase the surface density of hydroxyl groups, the nanoparticles were calcinated in the presence of oxygen at 500 C for 24 h. 27,28 Then, the hydrophilic silica nanoparticles were dispersed in a mixture of 2-3 vol% of APTES in ethanol under stirring for 24 h (room temperature). Indeed, surface modification was done through the reaction of hydrolyzed ethoxy groups of APTES with the silanol groups on the surface of the silica nanoparticles.…”

“…The same results were reported in our previous work for these samples, based on X-ray diffraction analysis. 27 Based on the Lauritzen-Hoffman theory, the difference between the equilibrium melting point and crystallization temperature (ΔT=T m À T c ), called undercooling, is the main driving force for crystal nucleation and reflects the melting point depression due to the crystallite size. 45 Figure 8 represents the plotted equilibrium melting points, of the nanocomposite samples, against the nanoparticles content.…”

A scaling theory to approximate the thermal conductivity of the interphase region in polymer nanocomposites

“…As it is illustrated in Figure 5, regardless of the nanoparticles content, the thermal conductivity of the cluster is always in between that of the nanoparticles and the polymer matrix. Accordingly, even after aggregation/ 39 The numbers in the figures denote the size of the aggregates/agglomerates in nm (Scale bars: 1 μm). Table 3.…”

Using Thermomechanical Properties to Reassess Particles’ Dispersion in Nanostructured Polymers: Size vs. Content

“…Technological advances have allowed the development of new nanoparticles and the improvement of processing techniques for the preparation and design of nanocomposites, and despite the fact that nanocomposites have been studied for decades, several authors have recently devoted their work to providing new findings in various fields, such as ballistics [ 146 ], sensors [ 147 ], water treatment [ 148 ], conducting polymer composites [ 149 ], synergetic effects of self/induced crystallization and nanoparticles on the mechanical properties of nanocomposites [ 150 ], mechanical properties increment based on carbon nanoparticles, nanosilicon, and cobalt [ 111 , 151 , 152 , 153 , 154 ], besides thorough, updated, state-of-the-art reviews [ 155 , 156 ].…”