Melt Shear Rheology and pVT Behavior of Polypropylene / Multi-Walled Carbon Nanotube Composites

2018 ◽  
Vol 55 (4) ◽  
pp. 482-487 ◽  
Author(s):  
Nicoleta Violeta Stanciu ◽  
Felicia Stan ◽  
Catalin Fetecau
Keyword(s):  
Superposition Principle ◽  
Melt Temperature ◽  
Shear Rates ◽  
Pvt Data ◽  
High Shear Rates ◽  
Nanotube Composites ◽  
Multi Walled Carbon Nanotubes ◽  
Time Temperature Superposition Principle ◽  
Increasing Temperature ◽  
Walled Carbon Nanotubes

In this study, capillary rheological tests were performed on polypropylene filled with multi-walled carbon nanotubes (PP/MWCNT) to determine the melt flow curves and pressure-Volume-Temperature (pVT) diagrams. Based on the experimental data, master viscosity curves were constructed using the time-temperature-superposition principle and the Cross and Carreau-Winter models, while the pVT data were fitted to the Tait equation in both liquid and solid states. Results show that the melt shear viscosity decreases with increasing melt temperature and shear rate and increases with MWCNT wt.%. All composites display shear-thinning behavior in the range of medium to high shear rates. The specific volume of PP/MWCNT composite decreases with increasing MWCNT wt.% and pressure and increases with increasing temperature.

scholarly journals Mechanical, Electrical and Rheological Behavior of Ethylene-Vinyl Acetate/Multi-Walled Carbon Nanotube Composites

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1300 ◽  
Author(s):  
Stanciu ◽  
Stan ◽  
Sandu ◽  
Susac ◽  
Fetecau ◽  
...  
Keyword(s):  
Vinyl Acetate ◽  
Mechanical Response ◽  
Ethylene Vinyl Acetate ◽  
Flow Index ◽  
Melt Temperature ◽  
High Shear Rates ◽  
Nanotube Composites ◽  
Multi Walled Carbon Nanotubes ◽  
Rheological Experiments ◽  
Walled Carbon Nanotubes

This paper investigates the rheological, mechanical and electrical properties of a Ethylene-Vinyl Acetate (EVA) polymer filled with 1, 3 and 5 wt.% multi-walled carbon nanotubes (MWCNTs). The melt flow and pressure-volume-Temperature (pvT) behaviors of the EVA/MWCNT composites were investigated using a high-pressure capillary rheometer, while the electro-mechanical response was investigated on injection-molded samples. Rheological experiments showed that the melt shear viscosity of the EVA/MWCNT composite is dependent on nanotube loading and, at high shear rates, the viscosity showed temperature-dependent shear thinning behavior with a flow index n < 0.35. The specific volume of the EVA/MWCNT composite decreased with increasing pressure and MWCNT wt.%. The transition temperature, corresponding to the pvT crystallization, increased linearly with increasing pressure, i.e., about 20 to 30 °C when cooling under pressure. The elastic modulus, tensile strength and stress at break increased with increasing MWCNT wt.%, whereas the strain at break decreased, suggesting the formation of MWCNT secondary agglomerates. The electrical conductivity of the EVA/MWCNT composite increased with increasing MWCNT wt.% and melt temperature, reaching ~10−2 S/m for the composite containing 5 wt.% MWCNTs. Using the statistical percolation theory, the percolation threshold was estimated at 0.9 wt.% and the critical exponent at 4.95.

Investigation of Structure-Property Relationships in Thermoplastic Polyurethane/Multiwalled Carbon Nanotube Composites

2017 ◽  
Author(s):  
Felicia Stan ◽  
Catalin Fetecau ◽  
Nicoleta V. Stanciu ◽  
Razvan T. Rosculet ◽  
Laurentiu I. Sandu
Keyword(s):  
Electrical Properties ◽  
Shear Viscosity ◽  
Thermoplastic Polyurethane ◽  
Structure Property ◽  
Multiwalled Carbon ◽  
Structure Property Relationships ◽  
Mechanical And Electrical Properties ◽  
High Shear Rates ◽  
Nanotube Composites ◽  
Multi Walled Carbon Nanotubes

In this study, the structure-property relationships in thermoplastic polyurethane (TPU) filled with multi-walled carbon nanotubes (MWCNTs) were investigated. Firstly, the contribution of MWCNTs to the melt shear viscosity and the pressure-volume-temperature (pVT) behavior was investigated. Secondly, injection-molded samples and 2 mm diameter filaments of TPU/MWCNT composites were fabricated and their mechanical and electrical properties analyzed. It was found that the melt processability of TPU/MWCNT composites is not affected by the addition of a small amount (1–5 wt.%) of MWCNTs, all composites displaying shear-thinning at high shear rates. The mechanical and electrical properties of the TPU/MWCNT composites were substantially enhanced with the addition of MWCNTs. However, the conductivity values of composites processed by injection molding were two and three orders of magnitude lower than those of composites processed by extrusion, highlighting the role of melt shear viscosity on the dispersion and agglomeration of nanotubes.

Dynamic electrical properties of polymer-carbon nanotube composites: Enhancement through covalent bonding

2006 ◽  
Vol 21 (4) ◽  
pp. 1071-1077 ◽  
Author(s):  
Seamus A. Curran ◽  
Donghui Zhang ◽  
Wudyalew T. Wondmagegn ◽  
Amanda V. Ellis ◽  
Jiri Cech ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Conductivity Measurement ◽  
Decomposition Temperature ◽  
Composite Formation ◽  
Nanotube Composites ◽  
Multi Walled Carbon Nanotubes ◽  
Charge Hopping ◽  
A New Technique ◽  
Covalently Linked ◽  
Walled Carbon Nanotubes

Composite formation between carbon nanotubes and polymers can dramatically enhance the electrical and thermal properties of the combined materials. We have prepared a composite from polystyrene and multi-walled carbon nanotubes (MWCNT) and, unlike traditional techniques of composite formation, we chose to polymerize styrene from the surface of dithiocarboxylic ester-functionalized MWCNTs to fabricate a unique composite material, a new technique dubbed “gRAFT” polymerization. The thermal stability of the polymer matrix in the covalently linked MWCNT-polystyrene composite is significantly enhanced, as demonstrated by a 15 °C increase of the decomposition temperature than that of the noncovalently linked MWCNT-polystyrene blend. Thin films made from the composite with low MWCNT loadings (<0.9 wt%) are optically transparent, and we see no evidence of aggregation of nanotubes in the thin film or solution. The result from the conductivity measurement as a function of MWCNT loadings suggests two charge transport mechanisms: charge hopping in low MWCNT loadings (0.02–0.6 wt%) and ballistic quantum conduction in high loadings (0.6–0.9 wt%). The composite exhibits dramatically enhanced conductivity up to 33 S m−1 at a low MWCNT loading (0.9 wt%).

Steady-State Shear Flow Properties of Carbon-Black Filled Rubber Compounds

1994 ◽  
Vol 67 (2) ◽  
pp. 207-216 ◽  
Author(s):  
S. Ertong ◽  
H. Eggers ◽  
P. Schümmer
Keyword(s):  
Carbon Black ◽  
Superposition Principle ◽  
Viscoelastic Behavior ◽  
Shear Rates ◽  
Creep Flow ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
Yield Values ◽  
Time Temperature Superposition Principle ◽  
Flow Experiments

Abstract The steady shear viscosities of four model rubber/carbon-black compounds are measured with a modified Weissenberg Rheometer in a range of moderate shear rates. Yield stresses and low-shear viscosities are determined from creep-flow experiments. Yield stresses are found to increase strongly with filler content while their dependence on temperature can be described by an Arrhenius-type function. Flow curves are reduced to master curves by means of the time-temperature superposition principle. The shift factors are well approximated by the WLF-relation. The contribution of the “secondary” carbon-black network to the viscoelastic behavior requires additional vertical shifting for the filled compounds. Viscosities are found to be in very good agreement with the Herschel-Bulkley model when using the experimentally determined yield values.

Modeling of Vertically Aligned Carbon Nanotube Composites for Vibration Damping

2009 ◽  
Author(s):  
J. Y. Jia ◽  
W. H. Liao
Keyword(s):  
Load Transfer ◽  
Epoxy Composite ◽  
Maxwell Model ◽  
Stick Slip ◽  
Slip Mechanism ◽  
Nanotube Composites ◽  
Multi Walled Carbon Nanotubes ◽  
Transfer Behavior ◽  
Vertically Aligned ◽  
Walled Carbon Nanotubes

High density aligned multi-walled carbon nanotubes (CNTs) and the CNT/epoxy composite are fabricated. To predict the energy dissipation in composites with vertically aligned multi-walled CNTs, a structural damping model of composite unit cell composed of resin, sheath and nanotube is developed. In this paper, the resin is described as viscoelastic material using Maxwell model. The CNT/epoxy composite is modeled based on the “stick-slip” mechanism, to describe the load transfer behavior between the CNT and its sheath. In order to further study the damping mechanism of the CNT composite, key parameters, such as length, center-to-center distance and critical stress of CNTs that are expected to affect the composite damping performances are studied. The simulation results show that loss factor of the CNT composite with varying parameters is sensitive to the applied stress.

Dynamic mechanical behavior of phenoxy/carbon nanotube composites: assessment through different functionalization

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Mahdi Najjar Disfani ◽  
Seyed-Hassan Jafari ◽  
Hossin Ali Khonakdar
Keyword(s):  
Mechanical Properties ◽  
Storage Modulus ◽  
Dynamic Mechanical Properties ◽  
Melt Mixing ◽  
Dynamic Mechanical ◽  
Transmission Electron ◽  
Dispersion State ◽  
Nanotube Composites ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Abstract Nanocomposites of phenoxy resin with various functionalized multi-walled carbon nanotubes (CNTs) were investigated to assess and compare the effect of functionalization on dynamic mechanical properties. Non-functionalized and various functionalized CNTs containing -COOH, -OH, and -NH2 groups were utilized for preparing phenoxy/CNT nanocomposites through a melt mixing process. Dynamic mechanical properties of nanocomposites, storage modulus (E′), and loss tangent (tanδ) data in temperature range of 20–120°C were collected. Transmission electron microscopy and optical microscopy were also used to gain an insight into the CNTs dispersion state within phenoxy matrix. The functionalized CNTs had no adverse effect on storage modulus of phenoxy. The morphological investigation revealed the highest degree of agglomeration and the shortest tube lengths for the CNT-COOH within phenoxy matrix.

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