Carbon Nanotube-Induced Changes of Crystal Growth In Polymer Films

2008 ◽  
Vol 1150 ◽  
Author(s):  
Georgi Yordanov Georgiev ◽  
Yaniel Cabrera ◽  
Lauren Wielgus ◽  
Zarnab Iftikhar ◽  
Michael Mattera ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multiwall Carbon Nanotubes ◽  
Crystallization Rate ◽  
Peak Time ◽  
Scanning Calorimetry ◽  
Avrami Analysis ◽  
Low Concentrations ◽  
Nucleation Agents ◽  
Speed Up ◽  
Induced Changes

AbstractIsotactic Polypropylene (iPP) nanocomposites with low concentrations of multiwall carbon nanotubes (CNTs) 0-1% were studied, using differential scanning calorimetry and Avrami analysis. The nanocomposites were isothermally crystallized at 135°C, in order to measure the effect of nanotubes on the kinetics of crystallization. In our study there is a great effect of the CNTs on the iPP crystallization kinetics. The Avrami analysis shows increase in the crystallization rate constant and constancy the Avrami exponent with increase of the CNTs concentration. The full width at half maximum (FWHM) of the heat flow exotherm and the peak time for crystallization (tp) change dramatically. For iPP, the carbon nanotubes serve as nucleation agents to speed up the crystallization process.

Crystallization Kinetics in Isotactic Polypropylene Films with Carbon Nanotubes

2011 ◽  
Vol 1312 ◽  
Author(s):  
Georgi Georgiev ◽  
Scott Schoen ◽  
Devin Ivy ◽  
Lauren Wielgus ◽  
Yaniel Cabrera ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Crystallization Kinetics ◽  
Isotactic Polypropylene ◽  
Crystallization Rate ◽  
Crystal Nucleation ◽  
Commercial Application ◽  
Peak Time ◽  
Slight Variation ◽  
Scanning Calorimetry ◽  
Avrami Analysis

ABSTRACTPolymer nanocomposites are the largest commercial application for carbon nanotubes (CNTs) which determines the interest in their effect on crystallization processes of polymers. We chose Isotactic Polypropylene (iPP) as one of the most widely used polymers. Nanocomposites with multiwall carbon nanotubes (MWCNTs) 0-5% by weight were studied, using differential scanning Calorimetry to measure the crystal nucleation and kinetics effects of MWCNTs. Isothermal crystallization at 138°C was performed and the data were analyzed using Avrami analysis. We obtained results for the effect of MWCNTs on the crystallization kinetics. The Avrami analysis showed a dramatic increase in the crystallization rate constant and constancy of the Avrami exponent with increase of the CNTs concentration. The full width at half maximum (FWHM) of the heat flow exotherm and the peak time for crystallization (tp) change dramatically. The crystallinity shows a slight variation with the CNTs concentration dipping at 2% CNTs which can be explored further at higher concentrations.

PP/MWCNTs composites: Effects of length of MWCNTs on isothermal crystallization behaviors, crystalline structure, and thermal stability

2017 ◽  
Vol 52 (4) ◽  
pp. 503-517 ◽  
Author(s):  
Zheng-Ian Lin ◽  
Ching-Wen Lou ◽  
Yi-Jun Pan ◽  
Chien-Teng Hsieh ◽  
Chien-Lin Huang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Stability ◽  
Crystalline Structure ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Scanning Calorimetry ◽  
Crystallization Behaviors ◽  
Walled Carbon Nanotubes ◽  
Thermal Stability Of

This study adopts the melt compounding method to prepare /mutli-walled carbon nanotubes composites. The effects of different lengths of the mutli-walled carbon nanotubes on the isothermal crystallization behaviors, crystalline structure, and thermal stability of the polypropylene/mutli-walled carbon nanotubes composites are examined. The PLM results show that the combination of mutli-walled carbon nanotubes prevents the growth of polypropylene spherulites, and thus results in a small size of spherulites. The differential scanning calorimetry results show that the short (S-) or long (L-) mutli-walled carbon nanotubes can function as the nucleating agent of polypropylene, which accelerates the crystallization rate of polypropylene. Avrami theory analyses indicate that the addition of short-mutli-walled carbon nanotubes particularly provides polypropylene/mutli-walled carbon nanotubes composites with a high crystallization rate. The X-ray diffraction results show that the combination of mutli-walled carbon nanotubes does not pertain to the crystal structure. The TGA test results show that long-mutli-walled carbon nanotubes outperform short -mutli-walled carbon nanotubes in improving the thermal stability of polypropylene, and both can significantly improve it.

Reinforcing Effects of Poly(D-Lactide)-g-Multiwall Carbon Nanotubes on Polylactide Nanocomposites

2015 ◽  
Vol 15 (10) ◽  
pp. 8086-8092 ◽  
Author(s):  
Jeong Hee Yang ◽  
Jae Yun Lee ◽  
In-Joo Chin
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Testing Machine ◽  
Multiwall Carbon Nanotubes ◽  
Hydroxyl Groups ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Polylactide (PLA) nanocomposites with multi-walled carbon nanotubes (MWNTs) grafted with poly(L-lactide) or poly(D-lactide) were prepared by solution casting, and their thermal and mechanical properties were evaluated. MWNTs containing hydroxyl groups were treated by ring-opening polymerization of either L-lactide or D-lactide. Fourier transform infrared spectroscopy confirmed that the MWNT surfaces had been modified by the PLLA or PDLA chains. The thermal properties were measured by differential scanning calorimetry and thermogravimetric analysis. The mechanical properties were examined using a universal testing machine. The morphology of the fractured surfaces of the PLA nanocomposites was observed by scanning electron microscopy and transmission electron microscopy. PDLA-g-MWNTs were dispersed more uniformly compared to PLLA-g-MWNTs in the PLA matrix. The incorporation of PDLA-g-MWNTs greatly improved the tensile strength of the nanocomposites regardless of the contents. Thermal analysis revealed different characteristics at specific composites depending on the type of modification.

scholarly journals Poly(ethylene Terephthalate) Carbon-Based Nanocomposites: A Crystallization and Molecular Orientation Study

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2626 ◽  
Author(s):  
Vasiliki F. Alexiou ◽  
George N. Mathioudakis ◽  
Konstantinos S. Andrikopoulos ◽  
Amaia Soto Beobide ◽  
George A. Voyiatzis
Keyword(s):  
Carbon Nanotubes ◽  
Polyethylene Terephthalate ◽  
Polymer Matrix ◽  
Molecular Orientation ◽  
Carbon Nanostructures ◽  
Multiwall Carbon Nanotubes ◽  
Polymeric Materials ◽  
Nucleation Agent ◽  
Scanning Calorimetry ◽  
Polarized Raman

Hybrid polymeric materials incorporating carbon nanostructures or inorganic constituents stand as a promising class of materials exhibiting distinct but also complementary features. Carbon nanotubes have been proposed as unique candidates for polymer reinforcement; however, sustained efforts are further needed in order to make full use of their potential. The final properties of the reinforced polymer are controlled in part by the morphology and the eventual molecular orientation of the polymer matrix. In the present study, multiwall carbon nanotubes (MWCNTs) were utilized in order to reinforce polyethylene terephthalate (PET) composites. The effect of CNTs on the crystallization and the orientation of the structurally hybridized polymeric material has been investigated from the perspective of assessing their impact on the final properties of a relevant nanocomposite product. Functionalized MWCNTs were used to achieve their optimal dispersion in the polymer matrix. The physical properties of the composites (i.e., crystallinity and orientation) were characterized via differential scanning calorimetry, X-ray diffraction, and polarized Raman microscopy. The addition of well-dispersed CNTs acted as a nucleation agent, increasing the crystallization of the polyethylene terephthalate matrix and differentiating the orientation of both CNTs and macromolecular chains.

MORPHOLOGY CONTROL OF CARBON NANOTUBES THROUGH FOCUSED ION BEAMS

NANO ◽  
2008 ◽  
Vol 03 (06) ◽  
pp. 449-454 ◽  
Author(s):  
M. LOYA ◽  
J. E. PARK ◽  
L. H. CHEN ◽  
K. S. BRAMMER ◽  
P. R. BANDARU ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Properties ◽  
Defect Engineering ◽  
Ion Milling ◽  
Induced Changes ◽  
Physical And Chemical ◽  
Multiwall Carbon

This research demonstrates the capability of controlled, focused ion beam (FIB)–assisted tailoring of morphologies in both multiwall carbon nanotubes (CNTs) and Y junction nonlinear CNT systems through defect engineering. We have shown that a 30 keV FIB Ga + ion beam at low ion milling currents of 1 pA can be used to partially reduce the CNT diameter, to provide electrical conduction bottleneck morphologies for linear CNTs, and to introduce both additive and subractive defects at Y junction locations of Y-CNT samples. Our aim is for this work to provide motivation for additional research to determine the effects of ion-beam-induced changes in modulating the physical and chemical properties of nanotubes.

Carbon Nanotubes Induced Changes in the Phase Diagram and Crystal Structure of 5CB Liquid Crystal

2011 ◽  
Vol 1293 ◽  
Author(s):  
Georgi Y. Georgiev ◽  
Michael B. McIntyre ◽  
Erin A. Gombos ◽  
Peggy Cebe
Keyword(s):  
Phase Transition ◽  
Carbon Nanotubes ◽  
Liquid Crystalline ◽  
Multiwall Carbon Nanotubes ◽  
Crystal Nucleation ◽  
Scanning Calorimetry ◽  
Crystal Forms ◽  
Polarized Microscopy ◽  
5Cb Liquid Crystal ◽  
Display Technology

ABSTRACTMultiwall Carbon Nanotubes (MWCNTs) form a nematic liquid crystalline (LC) phase in their lyotropic form, enabling their mixing and coupling of their director to that of nematic LCs. An important aspect of this LC/MWCNT interaction, for applications other than display technology, is looking at the ways the MWCNTs affect the physical properties of the LCs. We study the effect of MWCNTs on the nematic to crystal (N-C) phase transition of 4-cyano-4-npentylbiphenyl (5CB). Our Differential Scanning Calorimetry (DSC) results show a dramatic increase in N-C phase transition temperature of 14°C for only 0.1% and of 20°C for 1% MWCNT, due to the crystal nucleation activity of the nanotubes. Using Polarized Microscopy we observe a change in the crystalline order of 5CB from spherulitic at 0% MWCNTs to a multidomain in presence of MWCNTs. The new crystals resemble those formed by a smectic LC 4- Decyloxybenzoic acid. This is in line with predictions from simulations, that the MWCNTs form smectic order in nematic 5CB at their interface. MWCNTs induced modifications of the crystal phase of 5CB promise to create controlled novel crystal forms for the purposes of optical transmission and other applications.

Boehmite Nanofibers as a Dispersant for Nanotubes in an Aqueous Sol

2018 ◽  
Author(s):  
Gen Hayase
Keyword(s):  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Aqueous Solutions ◽  
High Aspect Ratio ◽  
Multiwall Carbon Nanotubes ◽  
Multiwall Carbon ◽  
Nanotube Films

By exploiting the dispersibility and rigidity of boehmite nanofibers (BNFs) with a high aspect ratio of 4 nm in diameter and several micrometers in length, multiwall-carbon nanotubes (MWCNTs) were successfully dispersed in aqueous solutions. In these sols, the MWCNTs were dispersed at a ratio of about 5–8% relative to BNFs. Self-standing BNF–nanotube films were also obtained by filtering these dispersions and showing their functionality. These films can be expected to be applied to sensing materials.

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