Tensile Strength and Young’s Modulus of Polyisoprene/Single-Wall Carbon Nanotube Composites Increased by High Pressure Cross-linking.

Tonpheng, Bounphanh; Yu, Junchun; Andersson, Britt M.; Andersson, Ove

doi:10.1021/ma101484e

Cited by 33 publications

(62 citation statements)

References 37 publications

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“…Consequently, the wrapped and/or coated layer of nylon-6 chains may become more strongly attached to the MWCNTs, which augment the irreversible densification. A similar augmented densification was previously observed in SWCNT/polyisoprene composites [9] in which the HP&HT treatment cause cross-linking instead of cold crystallization and therefore precludes that the effect is associated with a change in crystallinity.…”

Section: Degree Of Crystallinity Thermal Stability and Structural Prsupporting

confidence: 75%

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Microstructure, nucleation and thermal properties of high-pressure crystallized MWCNT/nylon-6 composites

Gröbner

Tonpheng

et al. 2011

Polymer

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This is an accepted version of a paper published in Polymer. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.Citation for the published paper: Yu, J., Gröbner, G., Tonpheng, B., "Microstructure, nucleation and thermal properties of high-pressure crystallized MWCNT/nylon-6 composites" Polymer, 52 (24) ABSTRACTMulti-wall carbon nanotube (MWCNT)/nylon-6 composites made by in-situ polymerization and subsequently modified by treatment at 1.0 GPa (or 1.7 GPa) and 530 K have been studied by WAXD, DSC and NMR. The pressure treatment gives an amorphous to crystalline transformation where the crystallinity increases from ~31% to as much as ~58% concurrently as the nylon-6 crystals increase in size and attain a preferred orientation relative to the applied pressure. A composite of 2.1 wt% purified MWCNT in nylon-6 shows significantly higher melting temperature than neat nylon-6 after identical pressure treatments. The improved thermal stability of the composite is attributed to crystal growth in the presence of reinforcing MWCNTs.The NMR spectrum of a pressure treated composite is similar to that of nylon-6 single crystals, which suggests a reduction of crystal boundaries after treatment, but there is no indication of covalent bonds between the nylon-6 chains and the MWCNTs.

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Section: Degree Of Crystallinity Thermal Stability and Structural Prsupporting

confidence: 75%

“…In the context of composites, these features can thus be exploited to investigate the possibility of augmented effects of fillers on the properties [9].…”

Section: Introductionmentioning

confidence: 99%

Microstructure, nucleation and thermal properties of high-pressure crystallized MWCNT/nylon-6 composites

Gröbner

Tonpheng

et al. 2011

Polymer

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“…In the swelling method, the samples were swelled in n-heptane or toluene at room temperature for 48 h. 21 A composite with 9.1 wt % P-MWCNT was also swelled further for 48 h with an additional weight increase of less than 1%, which confirms that 48 h swelling time is enough to reach near-equilibrium. The υ swell was estimated by the Flory−Rehner equation (see Supporting Information).…”

Section: ■ Experimental Sectionmentioning

confidence: 73%

“…testing speed and calculation of E, were the same as used previously. 21 To ensure accuracy and repeatability, at least two and occasionally three test pieces from the same sample were tested. (The preparation and analysis of one batch of a PI composite took about 7 days, which precluded a more extensive sample production.)…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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A MWCNT/Polyisoprene Composite Reinforced by an Effective Load Transfer Reflected in the Extent of Polymer Coating

Tonpheng

Gröbner

et al. 2012

Macromolecules

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Tensile and microstructural properties of multiwall carbon nanotube (MWCNT)/polyisoprene (PI) composites have been investigated after cross-linking achieved purely by simultaneous high-pressure high-temperature treatment. The method enables gradual increase of the cross-link density without interference of vulcanization chemicals, and the results suggest a link between an interfacial PI layer wrapped/coated on the MWCNTs and reinforcement in carbon nanotube (CNT)/PI composites. The interfacial layer, which is augmented by high-pressure treatment, was detected indirectly in swelling experiments and also reflected in results of atomic force microscopy. The results imply more efficient load transfer and mechanical reinforcement by CNTs with improved interfacial layer and that changes in the layer can be probed by swelling measurements. ■ INTRODUCTIONThe filler/polymer composite materials of today have a long history of development. 1,2 Various fillers such as carbon black, carbon fibers, silica, and clays, etc., 3 have been tested and proven favorable for mechanical and thermal reinforcement of polymers. But the recent discovery of new nanostructured materials and their extraordinary properties have raised expectations of major further improvements. 4 In particular, carbon nanotubes (CNTs) 5,6 and graphene 7 have mechanical and structural properties which are superior to those of the most commonly used fillers. 8 For example, assuming that CNTs in the perimeter of a bundle carried all the load, Yu et al. 9 obtained a tensile strength (σ UTS ) and a Young's modulus (E) of ∼22 and ∼1050 GPa, respectively, for a single-wall carbon nanotube (SWCNT) in a 19 nm bundle. Moreover, a 13 nm in diameter multiwall carbon nanotube (MWCNT) shows σ UTS of 28 GPa and E in the range from ∼270 to 950 GPa, 10 or an E average of 1.8 TPa, as reported by Treacy et al. 11 In general, theoretical calculations for SWCNTs and MWCNT indicate even higher strength and typically show σ UTS and E values of order of ∼1 TPa. 8,12 Besides the excellent mechanical properties, the unique structure with high aspect ratio (∼10 3 ) and low density make CNTs particularly interesting for the purpose of fabricating lightweight composites with high strength and stiffness. 1,13 In order to obtain CNT-based polymer composites with much improved mechanical performance, it is essential that the microstructure provides an efficient load transfer between the polymer matrix and the CNTs. 14 Covalent functionalization of CNTs is one method that opens the possibility of strong bonding between the otherwise essentially inert CNTs and a polymer matrix. The capability of this method is shown by Moniruzzaman et al.'s 15 results of more than 2 times higher σ UTS for fibers made of nylon-6, 10, and 1 wt % alkyl acid chloride group functionalized SWCNTs (SWCNT-(CH 2 ) n -COCl) than fibers of nylon-6, 10, and 1 wt % nonfunctionalized SWCNTs, which implies increased reinforcement due to covalent bonds between the nylon matrix and the functionalized CNTs. Another method to ob...

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Simple kinetic numerical model based on rheometer data for ethylene–propylene–diene monomer accelerated sulfur crosslinking

Milani¹

2011

J of Applied Polymer Sci

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A simple numerical model for the interpretation of the reaction kinetics in ethylene-propylene-diene monomer (EPDM) vulcanized with accelerated sulfur is presented. The model is based on the assumption that during vulcanization, a number of partial reactions occurs, both in series and in parallel, which determine the formation of intermediate compounds, including activated and matured polymers. Once written a standard first-order differential equation (DIFF-EQ) for each partial reaction, an ordinary DIFF-EQ system (ODEs), was obtained and solved through Runge-Kutta algorithms. Alternatively and more efficiently, a single second-order nonhomogenous DIFF-EQ with constant coefficients was deduced, for which a closed-form solution was derived, provided that the nonhomogenous term was approximated with an exponential function. Kinetic constants were evaluated through experimental data fitting on standard rheometer tests. To assess model predictions, an experimental campaign at different temperatures on two EPDM compounds was performed. They exhibited moderate reversion at intermediate and high curing temperatures. A nonlinear least-squares fitting was performed to evaluate unknown constants entering into the DIFF-EQ model proposed. Scaled rheometer curves fit rather well, also in the presence of reversion. In addition, partial reaction kinetic constants were provided: this gave an interesting insight into the different reticulation processes occurring during vulcanization.

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Tensile Strength and Young’s Modulus of Polyisoprene/Single-Wall Carbon Nanotube Composites Increased by High Pressure Cross-linking.

Cited by 33 publications

References 37 publications

Microstructure, nucleation and thermal properties of high-pressure crystallized MWCNT/nylon-6 composites

Microstructure, nucleation and thermal properties of high-pressure crystallized MWCNT/nylon-6 composites

A MWCNT/Polyisoprene Composite Reinforced by an Effective Load Transfer Reflected in the Extent of Polymer Coating

Simple kinetic numerical model based on rheometer data for ethylene–propylene–diene monomer accelerated sulfur crosslinking

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