Tensile Modulus Of Nanocomposites Research Articles

Development of Ji Micromechanics Model for Electrical Conductivity of Carbon Nanotubes-reinforced Samples

In this paper, Ji model for tensile modulus of nanocomposites is expanded to forecast the conductivity of polymer nanocomposites including carbon nanotubes (CNT) summarized as PCNT. The advanced model undertakes the volume fraction of networked CNT and the inherent resistances of tunneling and interphase sections. CNT loading, CNT size and interphase depth suggest the proportion of networked CNT. In addition, the tunneling confrontation is correlated to tunneling width, tunneling distance and polymer tunneling resistivity. The advanced model is used to express the parameters’ roles in the conductivity. Furthermore, the predictions of advanced model are linked to the experimental results of some examples. The proper impressions of all factors on the conductivity as well as the fine agreements among experimental data and calculations justify the advanced model. The radius and length of CNT mainly handle the conductivity, but CNT conduction is useless. Also, a dense interphase causes desirable conductivity, but the interphase conduction cannot govern the conductivity. Moreover, wide tunnels, deprived polymer tunneling resistivity and minuscule tunneling distance enhance the conductivity.

Quantitative evaluation of nanoparticle dispersion based on modeling methods and image analysis: A case study on nano‐Sb2O3 filled Poly (butylene terephthalate) composites

AbstractThe dispersion state of filler in polymer‐matrix composites plays a significant role in determining the performance of nanocomposites. Thus, the quantification of dispersion analysis for inclusions in polymer composites is crucial. In this paper, the robust methods for the quantitative assessment of dispersion are developed. The methods are based on the modeling evaluation and direct analysis of scanning electron microscopy micrographs using binary image technology. The dispersion degree in polymer nanocomposites reinforced with inorganic nanoparticles is calculated by modeling method. In addition, the effect of dispersion on the tensile modulus of nanocomposites is analyzed by modeling method. To further quantify the dispersion of nanoparticles, the mean distance value between nanoparticles is measured. The dispersion index D is defined as the probability of inclusion particles free‐path spacing, according to the frequency distribution of particle spacing data. The dispersion states of different samples are compared to examine the availability of the analysis methods to various dispersion conditions such as the effect of aggregation, agglomeration, cluster distribution, and surface treatment of nanoparticles. Besides, another modeling methodology is established based on inter‐particle distance of the nanocomposites. In this model, the dispersion of the nanoparticles is assessed by comparing the inter‐particle distance with the theoretical value assuming a perfect dispersion. In the case of nano‐Sb2O3 filled Poly (butylene terephthalate) composites, the composites with different dispersion and distribution characteristics were prepared. And the microstructures of these composites are also employed to access the applicability and functionality of the analysis methods.

Interphase characterization and modeling of tensile modulus in epoxy/silica nanocomposites

AbstractThe incorporation of second dispersed particulate phases in a polymer matrix enhances its mechanical properties. Because of the high surface to volume ratio of nanoparticles, the molecular structure of the matrix is altered at the nanoparticle/matrix interface and the volume of this perturbed region could be significant. These improved properties are produced by the interfacial interaction of the nanometric domains. In this research, epoxy matrix modified with three different sizes of nanosilica (12, 20, and 40 nm) and the effect of the interphase characteristics on the tensile properties of nanocomposites was investigated. At first, the theoretical values of the elastic modulus using a two‐phase mathematical model compared with the experimental data obtained from the nanocomposite samples and values between 8 and 10 nm were estimated for the interphase thickness. Afterward, considering the three‐phase model, it takes into account that three different regions for interphase volume fraction, including single particles, polymer trapping, and agglomerated nanoparticles, and an equation for evaluation of interphase volume fraction are defined. Also, the interphase tensile modulus was considered continuously changing from the properties of nanoparticle to the polymer matrix properties. Finally, the overall tensile modulus of nanocomposites, which considers different key parameters including nanoparticle size, values for the interphase thickness (h), and interphase tensile modulus (Ei), were calculated. The results were compared with the experimental ones of other studies and a good agreement was found. The smallest value of h as 6 nm for samples containing 12‐nm diameter nanosilica and highest value of h as 8 nm for samples containing 40‐nm diameter nanosilica is reported.

Effects of critical interfacial shear modulus between polymer matrix and nanoclay on the effective interphase properties and tensile modulus of nanocomposites

Many researchers have investigated the tensile modulus of polymer nanocomposites considering the interphase aspects, but have not considered the minimum interphase modulus that reinforces the nanocomposites. In this research, the critical interfacial shear modulus between polymer and nanoclay (Sc) in nanocomposites is determined mathematically to highlight its effects on the effective interphase properties. In addition, a model for the tensile modulus of polymer clay nanocomposites is developed by considering the clay size, clay morphology, interphase properties, “Sc” and interfacial shear modulus (Si). The predictions of the developed model are compared with experimental data for several samples. Additionally, the model’s calculations for different ranges of all parameters are validated. Good agreement is observed between the calculations and experimental values, validating the accuracy of the proposed model. A poor “Sc” and a high “Si” along with thin and large clay can positively control the efficiency of the interphase region and the modulus of the nanocomposites. A clay thickness (t) of 1 nm and clay length (l) of 11 μm increased the modulus of the polymer matrix by 120%, but for t > 4 nm, or t > 3 nm and l < 4 μm, there was only a 10% improvement in the nanocomposite modulus.

Simulation of tensile modulus of polymer carbon nanotubes nanocomposites in the case of incomplete interfacial bonding between polymer matrix and carbon nanotubes by critical interfacial parameters

In this paper, we correlate the minimum length of carbon nanotubes (CNTs) vital for operative stress transferring between polymer matrix and nanoparticles (Lc) to the critical interfacial shear modulus between polymer and CNTs (Gc) and the interfacial shear modulus (Gi) in the case of imperfect interfacial adhesion between polymer and carbon nanotubes (CNTs). Both “Gc” and “Gi” define the effective aspect ratio and volume fraction of CNTs in nanocomposites. Moreover, the developed Hui-Shia model investigates the roles of “Lc”, “Gc” and “Gi” in the tensile modulus of nanocomposites. The impacts of various parameters on the “Lc” and effective terms are highlighted. Furthermore, the experimental results of modulus for several samples and the influences of all parameters on the modulus evaluate the developed model. The accurate agreement between experimental and theoretical results as well as the correct roles of all parameters in the modulus supports the current approach. There is a direct relationship between the modulus of nanocomposites and “Lc”. Low “Gc” and high “Gi” as well as thin and long CNTs positively control the “Lc” and effective terms producing a high modulus for nanocomposites.

Role of critical interfacial shear modulus between polymer matrix and carbon nanotubes in the tensile modulus of polymer nanocomposites

The main purpose of this paper includes the definition of critical interfacial shear modulus (Gc) between polymer matrix and carbon nanotubes (CNT) and the investigation of its roles in the effective interphase properties and tensile modulus of polymer nanocomposites. Halpin-Tsai model is developed to determine the roles of “Gc”, interfacial shear modulus (Gi) and interphase properties in the tensile modulus of nanocomposites. The calculations of the developed model for the modulus of various samples are compared to the experimental results. Furthermore, the effects of all parameters on the tensile modulus of nanocomposites are explained to support the developed model. The original Halpin-Tsai model overestimates the tensile modulus of the samples, but the predictions of the developed model properly agree with the experimental data. The high “Gc” and poor interphase modulus cannot reinforce the nanocomposites. Also, CNT radius (R) > 15 nm considerably weaken the modulus of nanocomposites, but the modulus grows about 500% at R = 5 nm and interphase thickness (t) = 25 nm demonstrating the most important roles of these parameters in the modulus of nanocomposites.

Evaluation of surface modification impact on PP/MWCNT nanocomposites by rheological and mechanical characterization, assisted with morphological image processing

PP/MWCNT nanocomposites were prepared using polypropylene and modified carbon nanotubes (CNTs) via melt‐extrusion process. Pure PP was compared with maleic anhydride grafted polypropylene, reinforced with 0.5, 1, and 1.5 wt% COOH‐modified nanotubes (PPgCNT) and polypropylene/unmodified CNT nanocomposite (PPCNT) in 1 wt% content. Morphological analysis was performed using FTIR and SEM along with MATLAB and easy fit software‐assisted image processing. Image processing of SEM monographs for well‐distributed CNTs showed a distribution factor (β) close to 0 while β in agglomerated samples was close to 1. Mechanical properties showed that tensile strength and tensile modulus of nanocomposites were higher than pure PP, in contrast the tensile elongation at break was lower. In addition, nanocomposites with modified nanotubes showed higher tensile strength, tensile modulus, and lower elongation at break compare with unmodified CNT/PP nanocomposites. Capillary rheometries resulted that at high strain rate [100–1500 (s−1)], melting behavior of the samples is similar to the viscoplastic fluids, and Herschel‐Bulkley model is the best approach for prediction of the fluid's rheological behaviors. Adding the modified and unmodified CNTs only changed the model's parameters. Oscillating rheometry studies concluded that at 1% strain, molten nanocomposites followed the viscoelastic behavior while in higher shear rates flow behavior is different. According to the oscillatory rheometry results, storage modulus, loss modulus, complex modulus, and complex viscosity of PPgCNTs were higher than PP and PPCNT. It is concluded that by reduction of β, nanocomposites become more viscoplastic (in high shear rates). Finally, statistical analysis confirmed the rheological and mechanical results. POLYM. COMPOS., 40:E501–E510, 2019. © 2018 Society of Plastics Engineers

Strong Poly(Vinyl Alcohol) (PVA)/Bamboo Charcoal (BC) Nanocomposite Films with Particle Size Effect

In this paper, bamboo charcoals (BCs) were considered as alternative ecofriendly and sustainable carbon-based nanoparticles because of their good affinity with water-soluble biopolymer poly(vinyl alcohol) (PVA) to achieve strong PVA/BC nanocomposites. Two different types of BC particles, namely microdiameter bamboo charcoals (MBCs) and nanodiameter bamboo charcoals (NBCs) were successfully fabricated by the solution casting method. Nanofiller reinforcement effect was investigated from BC particle size and dispersion, morphological structures, and interfacial interactions between BCs and PVA matrices. Overall, the addition of NBCs yields increasingly higher mechanical properties of PVA/BC nanocomposites when compared with that of MBCs. The maximum enhancements in tensile moduli of nanocomposites were achieved up to 123% and 100% with the inclusion of 10 wt % NBCs and MBCs, respectively, whereas corresponding tensile strengths were improved by 110% and 72% with the incorporation of 3 wt % NBCs and MBCs acco...

Effect of nanosize CaCO3 and nanoclay on morphology and properties of linear PP/branched PP blend foams

Branched polypropylene (PP) polymer (BPP), two nanoparticles with different aspect ratios, nano CaCO3, and nanoclay (Cloisite 20A), were used for improving the melt strength of linear PP (LPP) and producing microcellular foam via a solid‐state foaming process using supercritical N2 as a physical foaming agent. The effects of BPP and nanoparticles were investigated on the rheological and mechanical properties of the nanocomposite and morphological properties of the foamed samples. The effect of temperature, saturation pressure, and foaming time were studied on the morphological properties of the foams, too. The results showed that the BPP increased the elongation at break of nanocomposite samples, and nano CaCO3 increased tensile strength, elongation at break, and tensile modulus, except at its highest content (15 wt%) and improving the dispersion of nanoclay. The nanoclay improved tensile strength and tensile modulus of nanocomposites, except at its highest content (6 wt%). The nanoclay increased the cell density and reduced the cell size and improved melt strength and cell stability during the foaming process. The nano CaCO3 improved foamability, cell size, and cell density. The simultaneous presence of nanoclay and nano CaCO3 synergistically improved the cell density and decreased the cell size of the foams. The best process conditions were found as 140°C temperature, 80 bar pressure, and 2 h time. The results of the DSC analysis showed that the crystallinity of foamed samples was higher than the nanocomposites and DMTA analysis showed that the tan δ of foamed samples was higher than unfoamed samples. POLYM. COMPOS., 40:E227–E241, 2019. © 2017 Society of Plastics Engineers

The presentation of an agro-environmental nanocomposite: the study of its acoustic, physical and mechanical properties

Nanocomposites can be used as an acoustic panel to adsorb noise. The aim of this study was to evaluate: (1) acoustic, (2) physical, and (3) mechanical properties of agro-environmental nanocomposites. To prepare the nanocomposites, wood flour, PVA glue, and aluminum nanoparticles (between 1 and 4 %) were hardly mixed and heated at near 220 °C for 120 min. In the next step, sound absorption coefficient, transmission loss, water absorption percentage, thickness swelling percentage, density, flexural strength, flexural modulus, tensile strength, and tensile modulus of nanocomposites were measured. This study showed that the increase in nanoparticle percentage led to the increase in flexural strength, flexural modulus, water absorption percentage, thickness swelling percentage, density, and sound absorption coefficient. But, the increase in nanoparticle percentage led to the decrease in tensile strength, tensile modulus, and transmission loss. The authors think that the nanocomposites are suitable as an agro-industrial nanocomposite to reduce noise.

Morphological, Mechanical and Thermal Properties of Chemically Bonded Graphene Oxide Nanocomposites with Biodegradable Poly(3-hydroxybutyrate) by Solution Intercalation

Chemically covalent bonded graphene oxide (MGO)/Poly(3-hydroxybutyrate) (PHB) nanocomposites were fabricated successfully through solution blending. Morphological observations indicated that MGO was dispersed well in the nanocomposites during solution intercalation. The mechanical and thermal property characterizations indicated that incorporation of 2.0 wt.% MGO resulted in the increasing of up to 101% and 46% in tensile strength and tensile modulus of nanocomposites, respectively, compared to neat PHB; while the maximum thermal decomposition temperature improved about 15.5 °C higher than that of PHB. Differential scanning calorimetric (DSC) analysis showed that the crystallization process of PHB accelerated, resulting in an increasing in crystallinity with the incorporation of MGO due to its’ “ nucleating effect”. Electrical conductivity analysis indicated that the electrical conductivity of MGO/PHB nanocomposites has increased by 14 orders in comparison to that of pure PHB, especially for r-MGO filled PHB nanocomposites (4 wt.% r-MGO loading). It was concluded that the formation of graphene-graphene network structure in the nanocomposites, the increases in homogeneous dispersion of graphene and interfacial interactions contributed to the enhancements of properties.

Influence of hydrogen functionalization on mechanical properties of graphene and CNT reinforced in chitosan biological polymer: Multi-scale computational modelling

A well tested multi-scale modelling approach, which was described and formulated in our previous work Ebrahimi et al. (2012), is employed to investigate the elasto-plastic behaviour of the chitosan (Cs) biological polymer embedded with a hydrogenated graphene (Gr–H), and a hydrogenated carbon nanotube (CNT–H). Without any need of a parameter fitting, and the inter-atomic potentials are directly linked into a continuum-based computation, via the Cauchy–Born rule. The continuum point within a finite element (FE) mesh in continuum level is represented by an atomic cluster. The results show that H-coverage and deformation of carbon nanostructures can lead to a drop in tensile modulus of nanocomposites. In addition, we show that, deformation of nanostructures play an important role in mechanical properties of nanocomposites.

Ultrasound assisted continuous‐mixing for the preparation of PP/SEBS/OMMT ternary nanocomposites

ABSTRACTPolypropylene (PP)/polystyrene‐block‐poly(ethylene‐co‐butylenes)‐block‐polystyrene (SEBS)/organo‐montmorillonite (OMMT) nanocomposites of varying concentrations of maleic anhydride‐grafted polypropylene (PP‐g‐MA) were prepared by continuous mixing assisted by ultrasonic oscillation. The structure and morphology of nanocomposites were investigated by X‐ray diffraction (XRD), transmission electron microscopy, and scanning electron microscopy. It was found that both PP‐g‐MA and ultrasonic oscillation could enhance the intercalation and exfoliation of OMMT in PP matrix. Meanwhile, the formation of PP could be induced by ultrasonic irradiation at a power of more than 540 W. Rheological properties including complex viscosity, storage, and loss modulus of nanocomposites were increased after adding PP‐g‐MA or ultrasonic treatment. The results of mechanical properties showed that PP‐g‐MA could improve the tensile strength and tensile modulus of nanocomposites, but with the sacrifice of impact strength. This problem could be improved by ultrasound due to the reduced particle size of SEBS. However, the mechanical properties would be reduced by ultrasonic treatment with higher intensity due to the polymer degradation. Therefore, the synergistic effect of both compatibilizer and ultrasound should account for the balance between toughness and stiffness of PP/SEBS/OMMT ternary nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41202.

Molecular dynamics simulations of the single-walled carbon nanotubes/poly (phenylacetylene) nanocomposites

The physical and mechanical properties of single-walled carbon nanotubes reinforced poly (phenylacetylene) are investigated here. Polymer density distribution, polymer atom distribution, stress–strain curve of single-walled carbon nanotubes/poly (phenylacetylene) and tensile and shear moduli of resulted nanocomposites are studied. It is shown that the polymer atom distribution at the nanotube/polymer interface is not uniform. It is observed that nanotube diameter and volume fraction do not affect polymer atom distribution around the single-walled carbon nanotubes significantly. Studying the effect of embedding nanotube in poly (phenylacetylene) on the tensile modulus of nanocomposite, it is shown that longitudinal Young’s modulus is improved drastically. However, transverse moduli are not significantly improved compared to pure polymer.

Rheology, Crystallization Kinetics and Mechanical Properties of HDPE/Vinyl-POSS Nanocomposites

Polyhedral oligomeric silsesquioxane (POSS) is usually prepared from the hydrolytic condensation of organotrialkoxysilanes. The rheology, non-isothermal crystallization kinetics and mechanical properties of high density polyethylene (HDPE)/vinyl-containing POSS (V-POSS) nanocomposites were investigated. The results show that the molten HDPE/V-POSS belong to pseudoplastic fluid. The V-POSS can accelerate the nucleation of HDPE at starting stage of crystallization. However, it will decrease the crystallization ability of HDPE in the subsequent crystallization process. The modified Avrami analysis by Jeziorny can well explain the crystallization behaviour of HDPE/V-POSS. The yield strength and tensile modulus of nanocomposites both increase when V-POSS content is 6%.

Study on Morphology, Rheology and Mechanical Properties of Thermoplastic Elastomer Polyolefin (TPO)/Carbon Nanotube Nanocomposites with Reference to the Effect of Polypropylene-grafted-Maleic Anhydride (PP-g-MA) as a Compatibilizer

The structure–property relationships of polypropylene/ethylene-propylene-diene (PP/EPDM) (80/20) nanocomposites containing single-walled carbon nanotubes (SWCNTs) by melt-mixing process were investigated, the main focus being on the effect of SWCNTs concentration and compatilizer content. Morphological observations by scanning electron microscopy (SEM) are presented in conjunction with the mechanical, thermal, and rheological properties of these nanocomposites. The tensile modulus of nanocomposites was enhanced by increasing the SWCNTs concentration. A high level of toughness in the thermoplastic elastomer polyolefin (TPO)/SWCNTs nanocomposite was achieved with 0.5 wt% of SWCNTs and 1 wt% of polypropylene-grafted maleic anhydride (PP-g-MA). Differential scanning calorimetry (DSC) experiments confirmed the nucleation effect of nanotubes on the crystallization process of the TPO/SWCNTs composites. An appreciable viscosity upturn and a non-terminal low frequency storage modulus were observed in nanocomposites containing SWCNTs whose values increased in the presence of compatibilizer.

Nylon 10 10–montmorillonite nanocomposite made by intercalating polymerization

AbstractNylon 10 10–montmorillonite nanocomposite has been prepared successfully using intercalating polymerization. The nanocomposite was investigated by X‐ray diffraction (XRD), Fourier transform infrared (FTIR), Atom force microscopy (AFM), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC), and Dynamic mechanical analysis (DMA). The results show that there are uniformly dispersed silicate layers in the nylon 10 10 matrix. The resulting nanocomposites have higher onset decomposition temperature and dynamic storage moduli than those of pure nylon 10 10. In addition, it was found that montmorillonite plays an important role in heterophase nucleation of the crystallization of nylon 10 10 in composites. Mechanical testing shows that the tensile modulus of nanocomposites is superior to that of nylon 10 10, and the ultimate strain values of the nanocomposites remain at a level similar to nylon 10 10 if the content of montmorillonite is not more than 6 wt%.