Rheological investigation of shear-enhanced crystallization for polylactide composites with different aspect ratio carbon nanotubes

2012 ◽  
Vol 32 (3) ◽  
Author(s):  
Zhaohua Xu ◽  
Ning Sun ◽  
Heng Li
Keyword(s):  
Carbon Nanotubes ◽  
Shear Rate ◽  
Aspect Ratio ◽  
Crystallization Process ◽  
Crystallization Rate ◽  
Matrix Composites ◽  
Multiwalled Carbon ◽  
Rheological Measurements ◽  
Nucleation Sites ◽  
Kinetics Of

Abstract Crystallization processes of polylactide (PLA)/acid oxidized multiwalled carbon nanotube (A-MWCNT) composites were detected by dynamic rheological measurements. The influences of pre-shear, crystallization temperature, concentration and aspect ratio of A-MWCNT, on the crystallization kinetics of PLA, were investigated. The addition of small amounts of A-MWCNT, can more or less accelerate the crystallization of the PLA matrix. Composites with smaller aspect ratio A-MWCNT (A-MWCNT–S) show faster crystallization rates than those with larger aspect ratio A-MWCNT (A-MWCNT–L), due to the more heterogeneous nucleation sites of the former. Pre-shear can significantly promote the crystallization process of PLA composites, and with the increase in shear rate, the crystallization rate becomes faster. Pre-shear results in an accelerated crystallization compared to PLA/A-MWCNT–S composites at the same concentration, without pre-shear, due to a more serious deformation from entanglement to orientation of A-MWCNT–L.

Functionalization of Multiwalled Carbon Nanotubes by Poly (Ethlylene Glycol) and Non-Isothermal Crystallization Kinetic Study

2011 ◽  
Vol 688 ◽  
pp. 127-134
Author(s):  
Song Gao ◽  
Kun Yan Sui ◽  
Zhi Ming Wu ◽  
Wen Wen Wu ◽  
Yan Zhi Xia
Keyword(s):  
Carbon Nanotubes ◽  
Crystallization Behavior ◽  
Crystallization Kinetic ◽  
Crystallization Rate ◽  
Avrami Equation ◽  
Nonisothermal Crystallization ◽  
Multiwalled Carbon ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Kinetics Of

Multi-walled carbon nanotubes (MWNT) were successfully chemically modified (MWNT-COOH) and reacted with polyethylene glycol (PEG) to prepare nanocomposites. As- prepared kinds of functionalized MWNT (MWNT-g-PEG) were characterized with FTIR, TGA and TEM. Nonisothermal crystallization kinetics of MWNT-g-PEG composites was investigated by differential scanning calorimeter (DSC). The kinetics was analyzed using the Ozawa and Avrami equation modified by Jeziorny. The results showed that the Ozawa approach failed to describe the crystallization behavior of nanocomposites, whereas the modified Avrami analysis could explain the behavior of MWNT-g-PEG nanocomposite only. It is observed that the presence of MWNT hindered the mobility of PEG chains and decreased the overall crystallization rate. It was found that the crystallization behavior of MWNT-g-PEG nanocomposite was strongly affected by the incorporation of MWNT. The data for the nonisothermal crystallization could be analyzed properly by the Avrami equation modified by Jeziorny. The results showed that the presence of MWNT decreased the overall nonisothermal crystallization rate of the PEG chains which were grafted onto the MWNT due to MWNT might act as physical hindrances retarding the mobility of PEG chains and decreased the crystallinity.

Non-Isothermal Crystallization Kinetics of Graphene Oxide-Carbon Nanotubes Hybrids / Polyamide 6 Composites

2019 ◽  
Vol 41 (3) ◽  
pp. 394-394
Author(s):  
Zhi Qiang Wang Zhi Qiang Wang ◽  
Yong Ke Zhao and Xiang Feng Wu Yong Ke Zhao and Xiang Feng Wu
Keyword(s):  
Carbon Nanotubes ◽  
Graphene Oxide ◽  
Cooling Rate ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Polyamide 6 ◽  
Degree Of Crystallinity ◽  
Isothermal Crystallization Kinetics ◽  
Kinetics Of

The hybrids combined by nano-materials with different dimensions usually possess much better enhancement effects than single one. Graphene oxide-carbon nanotubes hybrids / polyamide 6 composites has been fabricated. The non-isothermal crystallization kinetics of the as-prepared samples was discussed. Research results showed that increasing the cooling rate was in favor of increasing the crystallization rate and the degree of crystallinity for the as-prepared samples. Moreover, the crystallization rate was first decreased and then increased with increasing the hybrids loading. Furthermore, the crystallization mechanism was changed with increasing the crystallization temperature and the cooling rate. The nucleation and growth modes of the non-isothermal crystallization could be classified into three different types, according to the Ozawa’s theory. These complicated results could be attributed to the important role of crystallization rate as well as the simultaneous hindering and promoting effects of the as-prepared hybrids. This work has reference values for understanding the crystallization kinetics of the polyamide 6-based composites.

AMIDE FUNCTIONALIZATION OF MULTIWALLED CARBON NANOTUBES AND THEIR EVALUATION FOR Hg(II) REMOVAL FROM WATER

2011 ◽  
Vol 10 (01n02) ◽  
pp. 205-208 ◽  
Author(s):  
R. K. MISRA ◽  
S. K. JAIN ◽  
THOMAS N. ABRAHAM ◽  
P. K. KHATRI
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Chemical Interaction ◽  
Mercury Removal ◽  
Multiwalled Carbon ◽  
Kinetics Of Adsorption ◽  
Reaction Rate Constants ◽  
Hydrophilic Character ◽  
Short Time ◽  
Kinetics Of

This paper deals with the amide functionalization of multiwalled carbon nanotubes (MWNTs) and its evaluation for mercury removal from water. The functionalized MWNTs were characterized using FTIR for structural modification. The properties of MWNTs such as hydrophilic character, nature of surface, selective chemical interaction with mercury, etc., were significantly improved after functionalization making them promising adsorbents for mercury removal. The equilibrium is achieved in short time of 5 h resulting in up to 80% removal of Hg (II). Kinetics of adsorption was established and found to follow first-order reversible kinetics with forward and backward reaction rate constants 0.6648 and 0.1662, respectively.

Functional Nanodiamond Internalization Mechanisms and Kinetics

2010 ◽  
Author(s):  
Robert Lam ◽  
Xueqing Zhang ◽  
Mark Chen ◽  
Dean Ho
Keyword(s):  
Carbon Nanotubes ◽  
Drug Delivery ◽  
Surface Modification ◽  
Aspect Ratio ◽  
Biomedical Applications ◽  
Internalization Mechanism ◽  
Mechanism And Kinetics ◽  
Energy Dependent ◽  
The Relationship ◽  
Kinetics Of

Several reports have described the relationship between size, aspect ratio, surface modification and internalization for a variety of nanoparticles (i.e. gold, polymer, carbon nanotubes). Nanodiamonds (NDs) in particular have recently been implicated in a variety of biomedical applications. One of the most promising is in utilizing NDs as drug delivery carriers where successful internalization is of utmost importance. A few reports recently have demonstrated the energy dependent internalization of bare NDs. In this report, we investigate the internalization mechanism and kinetics of functional ND-conjugate translocation.

Aspect ratio control of acid modified multiwalled carbon nanotubes

2010 ◽  
Vol 10 (4) ◽  
pp. 1046-1052 ◽  
Author(s):  
Don-Young Kim ◽  
Young Soo Yun ◽  
Hyeonseong Bak ◽  
Se Youn Cho ◽  
Hyoung-Joon Jin
Keyword(s):  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Multiwalled Carbon Nanotubes ◽  
Multiwalled Carbon

Evaluation of mechanical and dynamic mechanical properties of multiwalled carbon nanotube-based ethylene–propylene copolymer composites mixed by masterbatch dilution

2016 ◽  
Vol 50 (29) ◽  
pp. 4093-4101 ◽  
Author(s):  
Maija Hoikkanen ◽  
Minna Poikelispää ◽  
Amit Das ◽  
Uta Reuter ◽  
Wilma Dierkes ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Aspect Ratio ◽  
Melt Mixing ◽  
Multiwalled Carbon ◽  
Mixing Processes ◽  
Ethylene Propylene ◽  
Dynamic Mechanical ◽  
Mixing Method

A two-step masterbatch mixing technique was studied for preparation of carbon nanotube-filled ethylene–propylene diene elastomer compounds, and compared to conventional one-step mixing process. In the two-step process, a masterbatch compound with carbon nanotube content of 50 parts per hundred was prepared by melt-mixing ethylene–propylene diene elastomer. This material was then compounded with pristine ethylene–propylene diene elastomer and composites with different carbon nanotube concentrations were compared. The aim of this study is to compare the efficiency of two different mixing processes on the dispersion of carbon nanotubes and to facilitate the handling of carbon nanotubes, as the masterbatch can be prepared in a controlled way and used for further dilution without the problems related to carbon nanotube processing. The compound properties were studied with emphasis on mechanical characterization and dynamic mechanical thermal analysis. Masterbatch mixing resulted in the similar mechanical properties of the composites compared to the direct mixing method. At the relatively low loadings of carbon nanotubes, the considerable improvements of the mechanical properties were observed. The aspect ratio of the carbon nanotubes determined by transmission electron microscope was found to be similar to the one calculated from the Guth equation. It showed a considerable reduction in aspect ratio independent of the used mixing method.

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