Weight Fraction Of Multi-walled Carbon Nanotubes Research Articles

Numerical and experimental investigation of first ply failure response of multi-walled carbon nanotubes/epoxy/glass fiber hybrid laminated tapered curved composite panels

In this study, first ply failure (FPF) analysis of multi-walled carbon nanotubes (MWCNTs)/epoxy/glass fiber laminated curved composite panels with various taper configuration under transverse uniform pressure load distributed over the panel surface has been performed. In this regard, various failure criterion were considered, including Hoffman, Tsai–Wu, Tsai–Hill, and maximum stress, to investigate the numerical FPF load using finite element (FE) formulation with displacement fields derived from high order shear deformation theory (HSDT) with displacement field having seven degrees of freedom. The effectiveness of the proposed formulation was validated by comparing the numerically predicted FPF load with experimentally obtained FPF load using a universal testing machine from displacement/strain measurement. Finally, the effects of aspect ratio, different weight fraction of MWCNTs, taper configuration, curved geometry, and aspect ratio on the FPF load of the laminated tapered composite panels are studied. The numerical and experimental studies of the first ply failure behavior have demonstrated that the use of MWCNTs ensures a significant improvement in the FPF load of the analyzed laminated tapered curved composite panels. The taper configuration 3 (TC-3) with hyperbolic curved geometry exhibited the highest resistance to failure than taper configuration 1 (TC-1) and taper configuration 2 (TC-2). Moreover, the aforementioned parameters significantly influence the FPF load of laminated curved panels with various taper configurations. Furthermore, this study can be effectively used as a benchmark problem for researchers and as a tool to design practical laminated tapered curved composite panels with sufficient accuracy.

Bending response analysis of a laminated, tapered, curved, composite panel made from an agglomerated and wavy MWCNT–glass fiber–polymer hybrid

The work investigates the influence of multiwalled carbon nanotubes (MWCNTs) on the bending behavior of laminated, spherical, cylindrical, hyperbolic, and elliptical tapered composite panels made from a MWCNT–glass fiber–polymer hybrid and subjected to transverse loading conditions. The deflection and stress behavior of the composite panels were studied by developing a mathematical model based on high-order shear deformation theory using finite element (FE) formulation. In this context, the agglomeration and waviness of MWCNTs were modeled and characterized using the Eshelby–Mori–Tanaka approach and a continuum mechanics based 3-D representative volume element (RVE), respectively. Subsequently, glass fiber was introduced as a reinforcement phase, and the elastic properties of the three-phase hybrid composite material were obtained using the Chamis model. The developed FE formulation was validated theoretically and experimentally. Further, detailed parametric studies were performed to examine the influence of micromechanical and structural characteristics such as weight fraction of MWCNTs, weight fraction of fiber, type of load, taper configuration, curved geometry, curvature ratio, and length to thickness ratio of the panel on the bending behavior of the composite panels. The effective laminated tapered curved composite panel, TC-3, tailored with improved MWCNT characteristics, can substantially resist the stresses from a bending load.

Effects on microstructure and mechanical properties of AZ31 reinforced with CNT by powder metallurgy: An overview

Reinforcement of AZ31 with different weight fractions of MWCNTs (Multi-Walled Carbon Nanotubes) was successfully done by powder metallurgy followed by sintering and hot extrusion to be implanted for bio-medical application. The different weight fractions of MWCTs used for reinforcement of AZ31 is 0.66 wt%, 1.5 wt%, and 4 wt%. SEM (Scanning Electron Microscope) and XRD (X-Ray Diffraction) images of each sample were obtained to examine the microstructure characterization. The effects on mechanical properties, microstructure, load transfer mechanism, and wear properties have been investigated during the work-study via tensile, micro hardness, compression, and wear tests. The detailed review of reinforcement of AZ31 with MWCNTs and their influence on various properties have been discussed in this paper.

Stability and Thermo-Physical Properties of Ethylene Glycol Based Nanofluids for Solar Thermal Applications

This article summarizes research involving the evaluation of the thermo-physical properties of ethylene- glycol-based solar thermic fluids oxidized multi-walled carbon nanotubes. Nanofluids were prepared with Ethylene glycol and water as base fluids in 100:0, 90:10 and 80:20 ratios. Base fluids of three categories were dispersed with surfactant-assisted multi-walled carbon nanotubes (MWCNTs) and oxidized MWCNTs in the weight fractions of 0.125, 0.25, and 0.5 percentages to check the influence of surface modification technique on the thermophysical properties. The variation in zeta potential is studied to examine the dispersion stability during 2 months. Thermal conductivity and dynamic viscosity were measured by hot disk method and Anton paar viscometer, respectively. Significant enhancement of thermal conductivity by 15 to 24 % was observed when the base fluids are dispersed with oxidized MWCNTs. In the case of nanofluids dispersed with surfactant-assisted MWCNTs, the improvement is significantly less compared to oxidized MWCNTs. Nanofluids' dynamic viscosity is found to be higher compared to base fluids in the temperature range of 50 to 70 oC. A comprehensive mathematical equation suitable for all weight fraction of MWCNTs and volume percentages of Ethylene glycol was developed, which can forecast the temperature range. The correlation could fit well with the experimental data in reasonable limits.

Creep deformation of poly(methyl methacrylate)-multiwalled carbon nanotube composites

Considering the long-term structural stability of polymer-nanotube composites under different service conditions, we investigate the tensile creep of polymer-nanotube composites consisting of poly(methyl methacrylate) (PMMA) and multiwalled carbon nanotubes (MWCNTs). The PMMA is pre-irradiated by ultraviolet light with different doses to change the molecular weight. The creep deformation of the PMMA-MWCNT composites with the weight fraction of MWCNTs in a range of 0 to 0.7 wt.% in a temperature range of 50 to 80 °C is well described by a Maxwell standard model with parallel connection between a spring, E1, and a Maxwell element (a dashpot, η, in the series connection with a spring, E2). The value of E1 is a linear function of the inverse of the normalized weight fraction with the average values of the coefficients/constants for the linear relation being increasing functions of the weight fraction of MWCNTs. The value of η is a power function of the molecular weight with a power index of ~3.3. The activation energy for the creep deformation of the PMMA-MWCNT composites increases with the increase of the weight fraction of MWCNTs.

Experimental and theoretical studies of free vibration of a sandwich functionally graded nanocomposite beam under thermal condition

The free vibration analysis of a sandwich three-layer functionally graded beam is studied experimentally and theoretically based on Timoshenko beam theory. The beam consists of a pure epoxy in the mid-plane and two inhomogeneous multi walled carbon nanotube (MWCNT)/epoxy nanocomposite on the upper and lower layers. The effect of weight fraction of MWCNT on the first natural frequency are obtained theoretically and experimentally and then compared with each other in this study. The effect of distribution of MWCNT is studied through a semi-analytical approach. A detailed parametric study is conducted on functionally graded MWCNT/epoxy beams. The effects of geometrical parameters, boundary conditions, slenderness ratio and temperature change are also studied. The differential quadrature method is employed as a numerical method to solve the equations of motion. The main contribution of this work is to present comparable experimental and theoretical results for sandwich functionally graded beams. Comparison of the results revealed that the obtained non-dimensional frequencies from theoretical approach are in good agreement with experimental results, especially for lower weight fractions of carbon nanotubes.

Experimental Study on Thermal Conductivity and Magnetization Behaviors of Kerosene-Based Ferrofluid Loaded with Multiwalled Carbon Nanotubes.

Kerosene-based ferrofluid (FF) loaded with multiwalled carbon nanotubes (MCNTs) is prepared and characterized to enhance heat conduction and furthermore for potential application in high-speed ferrofluid seals. The present study investigates kerosene-based ferrofluid loaded with MCNTs for the thermal conductivity and magnetization behaviors by varying temperature, weight fractions of MCNTs, and functional groups of MCNTs. The thermal conductivity is then measured by using a transient hot wire method, and magnetization behaviors are measured by using vibrator sample magnetometers. Microstructures among MCNTs and microstructures between MCNTs and magnetic nanoparticles in nanofluids are analyzed by optical microscopy and transmission electron microscopy. Experiments are carried out in the temperature range of 20–50 °C, MCNT weight fraction range of 0–1% for kerosene-based ferrofluid loaded with pristine MCNTs (p-MCNTs), MCNTs functionalized with carboxylic groups (MCNTs-COOH), and MCNTs functionalized with hydroxyl groups (MCNTs-OH). Results show that thermal conductivity and magnetization of FF + MCNTs nanofluids decrease with the increase in temperature. The addition of MCNTs increases the thermal conductivity and decreases the magnetization of the original ferrofluid, especially in the FF + p-MCNTs nanofluids. Furthermore, the addition of 1 wt % p-MCNTs increases the thermal conductivity and decreases the magnetization of the original ferrofluid by 12.47 and 7.73%, respectively. Moreover, the FF + 1 wt % p-MCNTs nanofluid can be stable for at least eleven weeks, which might be basically applied to high-speed ferrofluid seals.

Investigation of the effect of multi wall carbon nano tubes on the dynamic characteristics of woven kevlar/carbon fibers-polyester composites

This research offers an experimental and numerical study on the influence of multi-wall carbon nanotubes (MWCNTs) addition with different weight fractions on the dynamic characteristics of the unsaturated polyester (UP) reinforced by hybrid laminate composites. The laminate composites were prepared for only three layers as a total number of layers in such composites using Kevlar fibers and/or carbon fibers with different volume fractions. Both types of fibers were in the form of plain woven at (0°/90°) angle direction. Hand lay-up method was used to prepare the test samples. It was found that The best mechanical and dynamic properties based on the experimental study have been obtained for unsaturated polyester reinforced with (MWCNTs) particles at weight fraction (0.4% wt). Composite material made of unsaturated polyester reinforced with (MWCNTs) particles was also prepared with the same weight fraction of MWCNTs. Finite element method was used to model the free vibration of a cantilever beam made of composite material. ANSYS software composite Prep-Post (ACP) integrated within ANSYS Workbench software (18.2) was used to solve the FE problem. Field emission scanning electron microscopy (FESEM) and scanning electron microscopy (SEM) are applied to check the morphological properties of the composite material and the dispersion of MWCNT nanoparticles in the polymer matrix. Experimental and numerical Results obtained in the present work showed that the natural frequency and damping ratio of nano composite specimens increase with increasing weight fraction of MWCNTs. The results also showed that composite and hybrid composite materials with (0.4% wt) MWCNTs have higher values of natural frequency and damping ratio. It was found that the natural frequency for the hybrid nano composite with stacking sequence (UP + K/K/K + MWCNT) increased by about 10.4% when adding MWCNTs compared with (UP + K/K/K) laminated composite while it becomes 13.82% and 5.8% for (UP + K/C/K + MWCNT) and (UP + C/K/C + MWCNT) hybrid nano composite material in comparison with that without MWCNTs. The increase percentages of the damping ratio of the such materials have been calculated and it was found to be, 12.23%, 15.9% and 8.6%, respectively. An agreement between the experimental and numerical results has been obtained from flexural and vibration tests with maximum errors not exceeded 3.4% and 9.34%, respectively.

Thermal Diffusivity Behaviour of Multi-walled Carbon Nanotube Reinforced Ti6Al4V Metal Matrix Composites

This study investigated the thermal diffusivity behaviours of spark plasma sintered (SPS) multi-walled carbon nanotubes (MWCNTs) reinforced Ti6Al4V composites containing 0, 1, 2 and 3 wt. % of the reinforcement respectively, over a range of 50 – 300 °C. The MWCNTs were dispersed into the Ti6Al4V matrices by high-energy ball milling (HEBM) technique and the milled composite powders were consolidated by SPS under a vacuum atmosphere. The sintering conditions employed were heating rate (100 °C/min), holding time at temperature (5 min), sintering temperature (850 °C) and applied pressure of 50 MPa. The relative densities of the composite discs were measured according to Archimedes’ principle while the thermal diffusivities of as-sectioned composite samples were measured using the Laser Flash equipment. Relative densities of the synthesized nanocomposites deteriorated with increase in the weight fraction of MWCNTs added to Ti6Al4V. The thermal diffusivities of the composites containing 1 and 2 wt. % MWCNTs improved with increase in temperature and weight fraction of MWCNTs contents. A reverse trend was observed in the composite containing 3 wt. % MWCNTs, as the measured thermal diffusivities continued to drop with increase in temperature. Although this composite exhibited the best thermal diffusivities compared to the other composites up to 200 °C, a significant drop in thermal diffusivity was recorded between 250 and 300 °C respectively with the values lower than that of the unreinforced Ti6Al4V alloy. However, the thermal diffusivities of MWCNTs/Ti6Al4V composites were generally not dependent on their densification as the composites with higher weight fractions of the reinforcement had higher thermal diffusivities in spite of their lower relative densities.

Thermal Diffusivity Behaviour of Multi-walled Carbon Nanotube Reinforced Ti6Al4V Metal Matrix Composites

This study investigated the thermal diffusivity behaviours of spark plasma sintered (SPS) multi-walled carbon nanotubes (MWCNTs) reinforced Ti6Al4V composites containing 0, 1, 2 and 3 wt. % of the reinforcement respectively, over a range of 50 – 300 °C. The MWCNTs were dispersed into the Ti6Al4V matrices by high-energy ball milling (HEBM) technique and the milled composite powders were consolidated by SPS under a vacuum atmosphere. The sintering conditions employed were heating rate (100 °C/min), holding time at temperature (5 min), sintering temperature (850 °C) and applied pressure of 50 MPa. The relative densities of the composite discs were measured according to Archimedes’ principle while the thermal diffusivities of as-sectioned composite samples were measured using the Laser Flash equipment. Relative densities of the synthesized nanocomposites deteriorated with increase in the weight fraction of MWCNTs added to Ti6Al4V. The thermal diffusivities of the composites containing 1 and 2 wt. % MWCNTs improved with increase in temperature and weight fraction of MWCNTs contents. A reverse trend was observed in the composite containing 3 wt. % MWCNTs, as the measured thermal diffusivities continued to drop with increase in temperature. Although this composite exhibited the best thermal diffusivities compared to the other composites up to 200 °C, a significant drop in thermal diffusivity was recorded between 250 and 300 °C respectively with the values lower than that of the unreinforced Ti6Al4V alloy. However, the thermal diffusivities of MWCNTs/Ti6Al4V composites were generally not dependent on their densification as the composites with higher weight fractions of the reinforcement had higher thermal diffusivities in spite of their lower relative densities.

Influence of different parameters on cured shapes and residual stresses of unsymmetric composite laminate reinforced by multi-wall carbon nanotubes

In this research, the curvature of three-phase unsymmetrical composite laminates was determined based on the Rayleigh–Ritz energy method. Three-phase composite laminate consists of glass fiber, epoxy resin and multi-walled carbon nanotubes (MWCNTs). Micromechanical models including Halpin–Tsai, modified Schapery, bridging and Schapery models have been employed to determine mechanical and thermal properties of nanocomposite plates. The influence of the thickness, curing temperature and weight fraction of MWCNTs were studied analytically. Then, some cross-ply composite specimens were fabricated and the analytical results were certified by experimental ones. Additionally, the results were compared with the Hyer model. It was observed that the proposed model can predict the curvature behavior better than the Hyer model. Study of the effects of mentioned parameters on the curvature of the cross-ply laminates revealed that addition of MWCNTs leads to increase in the elastic modulus and decrease in the CTE. So, the curvature of unsymmetrical cross-ply laminates decreases by addition of appropriate amount of nanoparticles.

The thermal degradation and dynamic mechanical properties modeling of MWCNT/glass fiber multiscale filler reinforced polypropylene composites

The present work is focused to explore the influence of multiscale fillers (nano scale multiwalled carbon nanotubes (MWCNTs) and micro scale Glass fibers) on the thermal degradation and dynamic mechanical properties of polypropylene (P). MWCNTs weight fraction was varied up to 5 wt% for a fixed glass fiber fraction of 20 wt% and the resultant composite was characterized using X-ray diffraction, Scanning and Transmission Electron Microscopy. Hybrid composites with 2 wt% MWCNTs presented 101% increase in the activation energy for thermal degradation compared to the base matrix. The synergism of multiscale fillers could be clearly verified by the improved storage and loss modulus of the composite with 3 wt% MWCNT which is related to better interfacial interaction of fillers with the matrix. The lowering of tan δ peak suggested the rise in entanglement density of polymer chains on the fillers and decrease in the damping behavior of the composites was observed till 3 wt% of MWCNTs both by experimental and theoretical model values. Beyond 3 wt% of MWCNTs agglomeration effects caused decline in the dynamic mechanical properties.

Impact and flexural properties of polypropylene composites reinforced with multi-walled carbon nanotubes

The effects of content and size of multi-walled carbon nanotubes (MWCNTs) on the impact and flexural properties of reinforced-polypropylene (PP) composites were investigated at room temperature. The results showed that the flexural modulus and maximum flexural stress increased with increase of the MWCNTs weight fraction, while effects of the diameter and average length-diameter ratio of the fillers on the flexural strength were insignificant. The effects of the size and content of the MWCNTs on the impact fracture toughness were significant, the Izod V-notched impact fracture strength increased roughly with increasing weight fraction and the average diameter of the MWCNTs, while it decreased with increasing length-diameter ratio of the MWCNTs. Finally, the reinforcing and toughening mechanisms of the PP/MWCNTs composites are discussed.

Mechanical and Thermal Properties of Multi-scale Carbon Nanotubes–Carbon Fiber–Epoxy Composite

Multi-scale composite material was developed by combining carbon fabric and multi-wall carbon nanotubes (MWCNTs) in epoxy matrix. Varying concentrations of MWCNTs were ultrasonically dispersed in epoxy resin and applied on carbon fabric followed by curing. Tensile and flexural tests were conducted to observe the influence of MWCNTs on the mechanical properties of carbon fiber-reinforced plastic (CFRP). Coefficient of thermal expansion (CTE), thermal stability and glass transition temperature were determined through dilatometry, thermo-gravimetric analysis and differential scanning calorimetry, respectively. The MWCNTs dispersion in the epoxy was characterized through optical microscopy and scanning electron microscopy. Fractured surfaces of tensile samples were examined through high-resolution scanning electron microscope to investigate the failure mechanism. Tensile and flexural strengths were improved by 60 and 54%, respectively, on addition of 0.25 wt% MWCNTs in CFRP composite. This enhancement was attributed to the micro-crack bridging effect of the MWCNTs. Nanotubes acted as nano-stitches by holding the matrix together, thereby increasing the load bearing capability. Glass transition temperature and CTE of the CFRP was reduced by addition of MWCNTs whereas MWCNT–CFRP was found thermally stable up to 350 $${^{\circ }}$$ C. Microscopy results showed that the nanotubes were well dispersed in the epoxy matrix. However, higher weight fraction of MWCNTs in the epoxy had promoted agglomeration.

Rapid in-situ reaction synthesis of novel TiC and carbon nanotubes reinforced titanium matrix composites

In-situ TiC and remained multi-walled carbon nanotubes (MWCNTs) reinforced Ti composites were synthesized using vacuum hot-press sintering and hot rolling. The effect of weight fraction of MWCNTs on microstructural evolution and mechanical properties of the Ti composites was investigated. The results indicated that both proportion and particle size of TiC increased in proportion to MWCNTs content, which resulted in different matrix microstructure, and the grains were obviously refined after rolling deformation. The hardness tests indicated that MWCNTs addition could make the composites harden, and 18.4% improvement in hardness was obtained after hot rolling. The significant improvement in both strength and hardness could be attributed to grain refinement, solid solution strengthening of carbon and dispersion strengthening of TiC particles and remained MWCNTs. A good combination of strength and ductility were achieved in Ti–1wt% MWCNTs composites, which were in accordance with the uniform distribution of smaller-sized TiC particles in Ti matrix.

Vibration, buckling and bending behavior of functionally graded multi-walled carbon nanotube reinforced polymer composite plates using the layer-wise formulation

Polymer matrix nanocomposites reinforced with uniformly dispersed and randomly oriented multi-walled carbon nanotubes (MWCNTs) are identified as excellent candidates for functionally graded structural members. This paper presents static and dynamic behavior of functionally graded polymer composite plates reinforced by randomly oriented multi-walled carbon nanotubes using novel layer-wise formulation concept. The weight fraction of MWCNTs in functional graded plate is represented by layer-wise variation along the thickness and MWCNTs are considered as uniformly dispersed in each layer. The effective elastic modulus of nanocomposite plate is predicted with modified Halpin-Tsai model, while the Poisson’s ratio and density are determined by rule of mixtures. System of governing equations are derived based on generalized higher order shear deformation (HSDT) plate theory and Navier technique is employed to obtain the solution for free-vibration, buckling and static bending problems of simply supported plates under axial and transverse loading conditions at various aspect-ratios. In order to understand the effect of important reinforcement and plate parameters on the natural frequencies, critical buckling loads and bending deflections, different parametric studies are conducted. Results reveal that different types of weight distributions have significant influence on structural characteristics.

Experimental investigation of heat transfer and pressure drop characteristics of non-Newtonian nanofluids flowing in the shell-side of a helical baffle heat exchanger with low-finned tubes

An aqueous solution of Xanthan Gum (XG) at a weight fraction as high as 0.2% was used as the base liquid, the stable MWCNTs-dispersed non-Newtonian nanofluids at different weight factions of MWCNTs was prepared. The base fluid and all nanofluids show pseudoplastic (shear-thinning) rheological behavior. Experiments were performed to compare the shell-side forced convective heat transfer coefficient and pressure drop of non-Newtonian nanofluids to those of non-Newtonian base fluid in an integrally helical baffle heat exchanger with low-finned tubes. The experimental results showed that the enhancement of the convective heat transfer coefficient increases with an increase in the Peclet number and the nanoparticle concentration. For nanofluids with 1.0, 0.5 and 0.2 wt% of multi-walled carbon nanotubes (MWCNTs), the heat transfer coefficients respectively augmented by 24.3, 13.2 and 4.7% on average and the pressure drops become larger than those of the base fluid. The comprehensive thermal performance factor is higher than one and increases with an increasing weight fraction of MWCNTs. A remarkable heat transfer enhancement in the shell side of helical baffle heat exchanger with low-finned tubes can be obtained by adding MWCNTs into XG aqueous solution based on thermal resistance analysis. New correlations have been suggested for the shell-side friction coefficient and the Nusselt numbers of non-Newtonian nanofluids and give very good agreement with experimental data.

The experimental and statistical investigation of the photo degradation of methyl orange using modified MWCNTs with different amount of ZnO nanoparticles

The main goal of this paper is the experimental and statistical investigation of the photo decomposition of methyl orange using decorated multi-walled carbon nanotubes (MWCNTs) with different amount of ZnO nanoparticles (MWCNT–ZnO). The synthesized photocatalysts are characterized by FTIR and TEM. The synthesis of ZnO nanoparticles in the all synthesized photocatalysts is confirmed using FTIR analysis. TEM results depict that the outer surface of MWCNTs have been successfully decorated with ZnO nanoparticles and enhancement of ZnO precursor leads to the augmentation of decorated ZnO nanoparticles. The photocatalytic performance investigation reveals that the photo degradation of methyl orange increases with respect to the UV irradiation time and weight fraction of different kinds of MWCNT–ZnO. However, the influence of weight fraction (0.1, 0.2 and 0.5% wt) on the decomposition of pollutant is higher than that of UV irradiation time (ranging from 5 to 30 min). The results show that the enhancement of decorated ZnO nanoparticles on the surface of MWCNTs leads to the increasing the photo decomposition of methyl orange. The statistical analysis using Duncan’s multiple range test confirms that there is a significant difference between different studied levels of UV irradiation time and weight fraction of MWCNT–ZnO in all of the prepared suspensions.

Effects of MWCNTs Size on Melt Flow Properties of Polypropylene Composites During Capillary Extrusion

The influence of multi-walled carbon nanotubes (MWCNTs) size including average diameter and length-diameter ratio on the melt flow behavior of polypropylene composites were investigated by means of a capillary rheometer in a temperature ranging from 190 to 230 °C and under apparent shear rates varying from 100 to 4000 s−1. It was found that the melt shear flow approximately obeyed the power law; the values of the melt shear viscosity increased with an increase of the filler weight fraction, while decreased with increasing the average diameter of the MWCNTs; the dependence of the melt shear viscosity on temperature roughly obeyed the Arrhenius equation; the relationship between the melt shear viscosity and the MWCNTs weight fraction was almost linear; the sensitivity of the melt apparent shear viscosity to the MWCNTs weight fraction was weakened with increasing the MWCNTs average diameter.

Non-isothermal crystallization properties of polypropylene composites filled with multi-walled carbon nanotubes

The influence of the filler size and content on the crystallization behavior of polypropylene (PP) composites filled with three multi-walled carbon nanotubes (MWCNTs) with different sizes was investigated by means of a differential scanning calorimetry (DSC). It was found that the values of the onset crystallization temperature, crystallization peak temperature and end crystallization temperature increased with increasing MWCNT weight fraction and with decreasing filler average diameter; the value of the crystalline degree of the composites increased slightly with increasing filler weight fraction. The values of the crystalline degree of the composites filled with MWCNTs with wide length-diameter ratio and small specific surface area were the lowest when the MWCNT weight fraction was lower than 4%, which can be attributed to weak interaction between the matrix and inclusions due to small specific surface area. Moreover, the total crystallization rate of the composites filled with a small amount of the MWCNTs could be significantly increased.