Co-reporter:Shasha Duan, Zhihui Wang, Ling Zhang, Jin Liu, and Chunzhong Li
ACS Applied Materials & Interfaces September 13, 2017 Volume 9(Issue 36) pp:30772-30772
Publication Date(Web):August 16, 2017
DOI:10.1021/acsami.7b08453
The manufacture of stretchable conductors with well-reserved electrical performance under large-degree deformations via scalable processes remains of great importance. In this work, a highly stretchable 3D conductive framework consisting of a polyurethane fiber mat (PUF) and poly(3,4-ethylenedioxythiophene) (PEDOT) is reported through facile approaches, electrospinning, and in situ interfacial polymerization, which was then backfilled with poly(dimethylsiloxane) to obtain 3D conductors. The excellent stretchability of the 3D conductive network imparted the as-prepared electrode a superior mechanical durability. Moreover, the applied strains can be effectively accommodated by the arrangement and orientation of the fibers resulting in a relatively stable electrical performance with only a 20% increased resistance at 100% stretching. Meanwhile, the resistance of the conductor could remain constant during 2000 bending cycles and showed a slight increase during 100 cycles of 50% stretching. The potential in the applications of large-area stretchable electrodes was demonstrated by the construction of LED arrays with the PUF-based conductors as electrical connections.Keywords: conductive; poly(3,4-ethylenedioxythiophene); polyurethane fiber mat; stretchable; three-dimensional structure;
Co-reporter:Zhihui Wang;Shasha Duan;Hao Jiang;Jianhua Shen;Chunzhong Li
Journal of Materials Chemistry C 2017 vol. 5(Issue 34) pp:8714-8722
Publication Date(Web):2017/08/31
DOI:10.1039/C7TC01727H
Achieving stretchable conductors with high stretchability and stable conductivity is a great challenge but urgent for multifunctional electronics applications. A novel kirigami-patterned stretchable conductive film (KSCF) with a highly tunable structure is prepared by laser cutting composites of carbon nanotube (CNT) conductive networks and an elastic poly(dimethylsiloxane) (PDMS) substrate. The kirigami film with an optimal structure exhibits both superior ultimate elongation as high as 430% and stable conductivity under high strain levels even up to 380%. More impressively, it also possesses excellent reversibility from 0 to 400% strain after 5000 repeated stretching cycles with negligible hysteresis and unchanged conductivity. The stress finite element modelling results further demonstrate that the effective stress-absorption through structural transformation is able to greatly enhance the KSCF stretchability and dynamic electrical stability. The as-prepared highly stretchable films present huge potential for emerging applications in stretchable electronics, especially those operating at high strain levels.
Co-reporter:Zhihui Wang;Shasha Duan;Hao Jiang;Jianhua Shen;Chunzhong Li
Journal of Materials Chemistry C 2017 vol. 5(Issue 34) pp:8714-8722
Publication Date(Web):2017/08/31
DOI:10.1039/C7TC01727H
Achieving stretchable conductors with high stretchability and stable conductivity is a great challenge but urgent for multifunctional electronics applications. A novel kirigami-patterned stretchable conductive film (KSCF) with a highly tunable structure is prepared by laser cutting composites of carbon nanotube (CNT) conductive networks and an elastic poly(dimethylsiloxane) (PDMS) substrate. The kirigami film with an optimal structure exhibits both superior ultimate elongation as high as 430% and stable conductivity under high strain levels even up to 380%. More impressively, it also possesses excellent reversibility from 0 to 400% strain after 5000 repeated stretching cycles with negligible hysteresis and unchanged conductivity. The stress finite element modelling results further demonstrate that the effective stress-absorption through structural transformation is able to greatly enhance the KSCF stretchability and dynamic electrical stability. The as-prepared highly stretchable films present huge potential for emerging applications in stretchable electronics, especially those operating at high strain levels.
Co-reporter:Shasha Duan, Ke Yang, Zhihui Wang, Mengting Chen, Ling Zhang, Hongbo Zhang, and Chunzhong Li
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 3) pp:2187
Publication Date(Web):December 29, 2015
DOI:10.1021/acsami.5b10791
The combination of carbon nanomaterial with three-dimensional (3D) porous polymer substrates has been demonstrated to be an effective approach to manufacture high-performance stretchable conductive materials (SCMs). However, it remains a challenge to fabricate 3D-structured SCMs with outstanding electrical conductivity capability under large strain in a facile way. In this work, the 3D printing technique was employed to prepare 3D porous poly(dimethylsiloxane) (O-PDMS) which was then integrated with carbon nanotubes and graphene conductive network and resulted in highly stretchable conductors (OPCG). Two types of OPCG were prepared, and it has been demonstrated that the OPCG with split-level structure exhibited both higher electrical conductivity and superior retention capability under deformations, which was illustrated by using a finite element method. The specially designed split-level OPCG is capable of sustaining both large strain and repeated deformations showing huge potential in the application of next-generation stretchable electronics.Keywords: carbon nanotubes; conductive; graphene; porous PDMS; stretchable; three-dimensional printing
Co-reporter:Yun Wang, Ling Zhang, Yanjie Hu, Chunzhong Li
Journal of Materials Science & Technology 2016 Volume 32(Issue 3) pp:251-258
Publication Date(Web):March 2016
DOI:10.1016/j.jmst.2015.11.008
A new type of transparent scratch resistant coatings including in-situ modified SiO2 (g-SiO2) in flame spray pyrolysis (FSP) process was prepared. The maximum content of g-SiO2 in the coating was 15 wt%, which is higher than that of SiO2 modified by traditional wet chemical route (l-SiO2, only 10 wt%). The results of transmission electron microscopy have demonstrated that in-situ surface modified g-SiO2 particles dispersed well with smaller agglomerates in the final coating, which was much better than the particles modified via wet chemical route. Visible light transmittance and haze tests were introduced to characterize the optical quality of the films. All coatings were highly transparent with the visible light transmittance of above 80%, especially for coatings containing g-SiO2, which exhibited slightly higher visible light transmittance than l-SiO2 embedded one. The haze value of coatings incorporated with 15 wt% g-SiO2 was 1.85%, even lower than the coating with 5 wt% l-SiO2 (haze value of 2.09%), indicating much better clarity of g-SiO2. The excellent optical property of g-SiO2 filled coatings was attributed to the good dispersion and distribution of particles. Nano-indention and nano-scratch tests were conducted to investigate the scratch resistance of coatings on nano-scale. The surface hardness of the coatings rose by 18% and 14%, and the average friction coefficient decreased by 15% and 11%, respectively, compared to the neat coat due to the addition of 10 wt% g-SiO2 and l-SiO2. The pencil hardness of the coating with 15 wt% g-SiO2 increased from 2B for the neat coating to 2H. However, the pencil hardness of coating with 10 wt% l-SiO2 was only H. The results showed that the g-SiO2 embedded coatings exhibited higher scratch resistance and better optical properties.
Co-reporter:Wenqiong Ye, Ling Zhang and Chunzhong Li
RSC Advances 2015 vol. 5(Issue 32) pp:25450-25456
Publication Date(Web):05 Mar 2015
DOI:10.1039/C5RA02126J
SiO2@poly(methyl methacrylate)–reduced graphene oxide (SiO2@PMMA–rGO) composites with outstanding thermal stability, robust mechanical performance and excellent conductivity have been prepared by dispersion polymerization and electrostatic assembly based colloidal blending. The simultaneous construction of well-segregated silica structures and interconnected graphene networks, not only efficiently avoids agglomeration of the incorporated nanofillers, but also ensures enhanced interfacial adhesion between the fillers and the PMMA matrix, endowing the resultant composite with high performance. Specifically, compared to the host polymer, the composite with collaborative structure exhibits high thermal stability, i.e. the decomposition temperature increases by 80 °C and shows robust mechanical properties with a 108% increase in modulus and a 125% improvement in hardness. Besides, an ultra-low percolation threshold of 0.23 vol% is also achieved and the electrical conductivity reached 15.1 S m−1 with only 2.7 vol% graphene loading, which is ∼8 orders of magnitude higher than that for SiO2–PMMA–rGO (where SiO2, PMMA and rGO were simply compounded without forming synergetic structures) with the same rGO loading. These results demonstrate that the SiO2@PMMA–rGO composite has great potential to be applied as mechanical, thermal, and electrical materials.
Co-reporter:Wenqiong Ye, Ling Zhang, Guowei Feng, Jing Ye, and Chunzhong Li
Industrial & Engineering Chemistry Research 2015 Volume 54(Issue 30) pp:7459-7464
Publication Date(Web):July 8, 2015
DOI:10.1021/acs.iecr.5b01921
Calcium carbonate@methyl methacrylate-polyvinyl chloride (CaCO3@PMMA–PVC) nanocomposites with outstanding mechanical performance have been successfully prepared. Precise control over the CaCO3 surface modification via a green, facile, and reproducible seed dispersion polymerization, not only efficiently avoids agglomeration of the incorporated nanofillers, but also ensures enhanced interfacial adhesion between components, endowing the resultant composite with high performance. Specifically, the maximum tensile strength of PVC composites was achieved when the addition of CaCO3@PMMA NPs is 4 wt %, and the grafting content is 25%. Compared to pure PVC (P-PVC), the composite shows robust mechanical properties with a 116.7% increase in modulus and a 57.0% improvement in hardness.
Co-reporter:Shasha Duan, Ling Zhang, Zhihui Wang and Chunzhong Li
RSC Advances 2015 vol. 5(Issue 115) pp:95280-95286
Publication Date(Web):05 Nov 2015
DOI:10.1039/C5RA19148C
Excellent optoelectric and adhesive properties are two crucial parts for the application of transparent conductive electrodes (TCEs). In this work, AgNWs are composited with PEDOT:PSS to prepare high-performance TCEs using a one-step rod-coating approach, where AgNWs are buried in PEDOT:PSS resulting in largely weakened roughness and lowered sheet resistance from 164 Ω sq−1 to 16 Ω sq−1 at 90.4% optical transmittance. Besides, the addition of Zonyl improved the wettability of hydrophilic PEDOT:PSS on hydrophobic substrates, which enhanced the adhesion of the AgNWs–PEDOT:PSS film. A sulfuric acid post-process further strengthened the interaction between PEDOT:PSS and the organic substrate contributing improved adhesion of the AgNWs–PEDOT:PSS composite film. The as-prepared film exhibits favorable stability in both cyclic deformations and solvent environments. The solution-processed fabrication, outstanding photoelectric performance and strong adhesion imparts the AgNWs–PEDOT:PSS with tremendous potential in the application of flexible electronics.
Co-reporter:Mengting Chen;Shasha Duan;Shilong Jing;Hao Jiang ;Chunzhong Li
Advanced Functional Materials 2014 Volume 24( Issue 47) pp:7548-7556
Publication Date(Web):
DOI:10.1002/adfm.201401886
Here, a novel and facile method is reported for manufacturing a new stretchable conductive material that integrates a hybrid three dimensional (3D) carbon nanotube (CNT)/reduced graphene oxide (rGO) network with a porous poly(dimethylsiloxane) (p-PDMS) elastomer (pPCG). This reciprocal architecture not only alleviates the aggregation of carbon nanofillers but also significantly improves the conductivity of pPCG under large strains. Consequently, the pPCG exhibits high electrical conductivity with a low nanofiller loading (27 S m−1 with 2 wt% CNTs/graphene) and a notable retention capability after bending and stretching. The simulation of the mechanical properties of the p-PDMS model demonstrates that an extremely large applied strain (εappl) can be accommodated through local rotations and bending of cell walls. Thus, after a slight decrease, the conductivity of pPCG can continue to remain constant even as the strain increases to 50%. In general, this architecture of pPCG with a combination of a porous polymer substrate and 3D carbon nanofiller network possesses considerable potential for numerous applications in next-generation stretchable electronics.
Co-reporter:Mengting Chen, Ling Zhang, Shasha Duan, Shilong Jing, Hao Jiang, Meifang Luo and Chunzhong Li
Nanoscale 2014 vol. 6(Issue 7) pp:3796-3803
Publication Date(Web):17 Jan 2014
DOI:10.1039/C3NR06092F
New flexible and conductive materials (FCMs) comprising a quartz fiber cloth (QFC) reinforced multi-walled carbon nanotubes (MWCNTs)–carbon aerogel (QMCA) and poly(dimethylsiloxane) (PDMS) have been successfully prepared. The QMCA–PDMS composite with a very low loading of MWCNTs (∼1.6 wt%) demonstrates enhanced performance in tensile strength (129.6 MPa), modulus (3.41 GPa) and electromagnetic interference (EMI) shielding efficiency (SE) (∼16 dB in X-band (8.2–12.4 GHz) region). Compared to the QC (where MWCNTs were simply deposited on the QFCs without forming aerogel networks) based PDMS composite, a ∼120%, 330% and 178% increase of tensile strength, modulus, and EMI SE was obtained, respectively. Moreover, the EMI SE of the QMCA–PDMS composite can further reach 20 dB (a SE level needed for commercial applications) with only 2 wt% MWCNTs. Furthermore, the conductivity of the QMCA–PDMS laminate can reach 1.67 S cm−1 even with very low MWCNTs (1.6 wt%), which still remains constant even after 5000 times bending and exhibits an increase of ∼170% than that of MWCNT–carbon aerogel (MCA)–PDMS at 20% strain. Such intriguing performances are mainly attributed to their unique networks in QMCA–PDMS composites. In addition, these features can also protect electronics against harm from external forces and EMI, giving the brand-new FCMs huge potential in next-generation devices, like E-skin, robot joints and so on.
Co-reporter:Xiaofang Han, Ling Zhang and Chunzhong Li
RSC Advances 2014 vol. 4(Issue 58) pp:30536-30541
Publication Date(Web):17 Jun 2014
DOI:10.1039/C4RA04182H
In the present study, we report a simple solution mixing method to prepare polydopamine-functionalized graphene–Fe3O4 (DGF) nanocomposites with high adsorption capacities and an easy-separation ability. Water-soluble Fe3O4 particles are firmly deposited onto the surfaces of graphene oxide (GO) via electrostatic and hydrogen interactions. The interaction between the GO and Fe3O4 particles can prevent the graphene nanosheets from restacking and the Fe3O4 particles from agglomeration. The introduction of dopamine to functionalize GO not only reduces the GO but also endows abundant chemical groups. The existence of polydopamine affords more active sites for adsorption and further enhances the interaction of the GO and Fe3O4 particles to obtain adsorbent materials with stable structures. The adsorption capacity of DGF nanocomposites for methylene blue (MB) is 365.39 mg g−1, which is much higher than that of graphene–Fe3O4 (GF) nanocomposite. Simultaneously, the DGF nanocomposites can be easily removed from polluted water after adsorption for MB by using a magnetic field, which is highly important for water conservation.
Co-reporter:Mengting Chen, Tao Tao, Ling Zhang, Wei Gao and Chunzhong Li
Chemical Communications 2013 vol. 49(Issue 16) pp:1612-1614
Publication Date(Web):04 Jan 2013
DOI:10.1039/C2CC38290C
We have manufactured a highly conductive and stretchable composite by backfilling a preformed graphene/MWCNT aerogel with poly(dimethylsiloxane) (PDMS). The electrical conductivity of our product can reach 2.8 S cm−1 with only 1.3 wt% graphene/MWCNT loading, and remains constant after 100 times repeated stretching by 20% and 5000 times bending.
Co-reporter:Tao Tao, Ling Zhang, Hao Jiang and Chunzhong Li
New Journal of Chemistry 2013 vol. 37(Issue 5) pp:1294-1297
Publication Date(Web):06 Mar 2013
DOI:10.1039/C3NJ00159H
We demonstrated a facile route to realize the synthesis of a functional mesoporous carbon-coated CNT network, which exhibited a high specific capacitance of 214 F g−1 at 10 mV s−1 with intriguing rate and stability due to the synergistic effect between them.
Co-reporter:Jie Jin;Wei Chen ;Chun-Zhong Li
Polymer Composites 2013 Volume 34( Issue 8) pp:1313-1320
Publication Date(Web):
DOI:10.1002/pc.22544
The conductive polyamide 66 (PA66)/carbon nanotube (CNT) composites reinforced with glass fiber-multiwall CNT (GF-MWCNT) hybrids were prepared by melt mixing. Electrostactic adsorption was utilized for the deposition of MWCNTs on the surfaces of glass fibers (GFs) to construct hybrid reinforcement with high-electrical conductivity. The fabricated PA66/CNT composites reinforced with GF-MWCNT hybrids showed enhanced electrical conductivity and mechanical properties as compared to those of PA66/CNT or PA66/GF/CNT composites. A significant reduction in percolation threshold was found for PA66/GF-MWCNT/CNT composite (only 0.70 vol%). The morphological investigation demonstrated that MWCNT coating on the surfaces of the GFs improved load transfer between the GFs and the matrix. The presence of MWCNTs in the matrix-rich interfacial regions enhanced the tensile modulus of the composite by about 10% than that of PA66/GF/CNT composite at the same CNT loading, which shows a promising route to build up high-performance conductive composites. POLYM. COMPOS. 34:1313–1320, 2013. © 2013 Society of Plastics Engineers
Co-reporter:Lei Jin, Ling Zhang, Danhua Su, and Chunzhong Li
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 13) pp:4927-4933
Publication Date(Web):March 15, 2012
DOI:10.1021/ie202306v
We developed an approach to prepare the multilayered 3D composites where aligned multiwalled carbon nanotubes (MWCNTs) were grown on the surface of quartz fiber cloths (QFCs) by chemical vapor deposition method. The morphologies of the MWCNTs-QFCs preforms were analyzed by field emission scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The results showed that the growth of high yield and uniform alignment of MWCNTs on the surface of QFCs could be controlled by the process. The unique MWCNTs-QFCs preforms, when served as connecting bridges for structural epoxy composites, demonstrated a significant enhancement of the interlaminar shear strength and electrical conductivity along in-plane and out-of-plane directions when compared to QFCs/epoxy composites without MWCNTs, making the MWCNTs-QFCs reinforcements meaningful in structural composites.
Co-reporter:Ling Zhang;Danhua Su;Lei Jin;Chunzhong Li
Journal of Materials Science 2012 Volume 47( Issue 14) pp:5446-5454
Publication Date(Web):2012 July
DOI:10.1007/s10853-012-6434-y
Glass fiber-multiwall carbon nanotubes (GF-MWCNTs) hybrid preforms were prepared by electrostatic assembly method. Negatively charged MWCNTs by oxidization treatment were directly adsorbed onto the surfaces of positively charged GF to form tunable structure. The thickness and morphology of GF-MWCNTs preforms can be controlled by the assembly pH value and the concentration of oxidized-MWCNTs solution. We demonstrate that GF-MWCNTs preforms have uniform and porous interconnected network structure of MWCNTs on the surfaces of GF using FESEM. The multi-scale composites with the hybrid preforms were prepared by melt compounding. The presence of MWCNTs with porous nanostructure helps in the formation of interpenetrating network with polyamide 6 (PA 6) at the interface layer. As a result, the tensile tests of these multi-scale composites exhibit higher tensile properties in comparison with composites with GF, showing a promising structural composite to replace the traditional GF-reinforced composites with limited improvement of the performance.
Co-reporter:Huiting Wang, Yanjie Hu, Ling Zhang and Chunzhong Li
Industrial & Engineering Chemistry Research 2010 Volume 49(Issue 8) pp:3654-3662
Publication Date(Web):March 23, 2010
DOI:10.1021/ie901782w
Self-cleaning transparent nanoporous films with high photocatalytic properties were obtained based on the self-assembly of TiO2 nanoparticles synthesized by H2/O2 combustion flames. Films were prepared from multilayer deposition of poly(sodium 4-styrenesulfonate)-treated TiO2 nanoparticles and SiO2 nanoparticles with electrostatic interaction by the adsorption of positively charged poly(diallyldimethylammonium chloride) via layer-by-layer assembly processes. The assembly conditions, such as the pH and concentration of a nanoparticle suspension that cause variation of the surface charge densities, were found to strongly affect the thickness and morphology of multilayer films. TiO2/SiO2 coatings assembled with 10 cycles reach effective photocatalysis with a maximum transmittance of 99.3% as well as a water droplet spreading time as short as 0.29 s. The photodegradation kinetics showed that multilayer films fabricated with 10 cycles are 4 times more active than films assembled with 5 cycles, indicating that flame-synthesized TiO2 with well crystallinity can be used to fabricate high transparent self-cleaning films at suitable assembly conditions. The photocatalytic degradation kinetics dominated by control of the number of assembled cycles was also discussed.
Co-reporter:Hongkang Wang, Wei Shao, Feng Gu, Ling Zhang, Mengkai Lu and Chunzhong Li
Inorganic Chemistry 2009 Volume 48(Issue 20) pp:9732-9736
Publication Date(Web):September 18, 2009
DOI:10.1021/ic901235n
Anatase TiO2 nanoshuttles have been successfully prepared via a hydrothermal method under alkaline conditions by employing titanate nanowires as the self-sacrificing precursors. The experimental results showed that a radical structural rearrangement took place from titanate wires to anatase TiO2 shuttles during the hydrothermal reaction on the basis of a dissolution−recrystallization process. The surface of titanate nanowires plays a key role in the transformation process by providing both the structural units (e.g., TiO6 octahedra) to realize anatase transformation and locations for the deposition and rearrangement of the dissolved structural units, while the formation of shuttle morphology is attributed to the minimization of surface energy with thermodynamically stable (101) facets of anatase TiO2. The shape and phase transformation process were foundto be dependent on the hydrothermal reaction time. Raman and photoluminescence spectra confirmed the crystalline nature of the TiO2 nanoshuttles.
Co-reporter:Ling Zhang;Yuerong Hong;Tianshui Zhang ;Chunzhong Li
Polymer Composites 2009 Volume 30( Issue 5) pp:673-679
Publication Date(Web):
DOI:10.1002/pc.20826
Abstract
Poly(butylenes terephthalate) (PBT)/SiO2 nanocomposites with uniform dispersion, strong interfacial adhesion, and improved mechanical properties have been prepared by a novel approach. Ethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA) elastomer chains were first chemically grafted onto the surface of SiO2 nanoparticles. Fourier transform infrared spectra result shows that elastomer-modified SiO2 nanoparticles exhibit absorption at 2963–2862 cm−1 of the stretching modes of CH, which suggests the reaction between the hydroxyl groups of SiO2 surface and epoxy groups of E-MA-GMA. And the binding energy of Si2p and O1s of the elastomer-modified SiO2 shifts to lower binding energy, which further confirms the formation of SiOC bonds. This surface treatment allows SiO2 nanoparticles homogeneously dispersing in PBT matrix. The morphology with loose aggregates contains networked SiO2 particles with an interparticle distance ranging from 0 to 30 nm. As a result, the storage modulus and the tensile properties of PBT/E-MA-GMA-SiO2 nanocomposites are higher than those of pure PBT and PBT with untreated SiO2. The incorporation of E-MA-GMA-modified SiO2 particles increases the tensile strength and modulus to 58.4MPa and 2661MPa respectively, which is 8% and 16% higher than those of pure PBT. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers
Co-reporter:Ling Zhang, Tao Tao, Chunzhong Li
Polymer 2009 50(15) pp: 3835-3840
Publication Date(Web):
DOI:10.1016/j.polymer.2009.05.051
Co-reporter:Ling Zhang;Chun Zhong Li;Qiuling Zhou;Wei Shao
Journal of Materials Science 2007 Volume 42( Issue 12) pp:4227-4232
Publication Date(Web):2007 June
DOI:10.1007/s10853-006-0630-6
Ethylene vinyl acetate (EVA) copolymer was filled with aluminum hydroxide (ATH) with three different sizes of 1.8, 1.2 and 0.8 μm in various volume fractions. The effect of interfacial compatibilizer on the properties of the composites was studied by morphology observation, dynamic mechanical analysis, tensile and flame tests. The results illustrated that the incorporation of functionalized polyethylene combined with dicumyl peroxide (DCP) and the silane coupling agent led to a pronounced improvement in the tensile strength compared to the composites with ATH untreated or treated by silane coupling agent alone. It was found that good dispersion and interfacial adhesion between the ATH particles and the matrix can improve the flame properties of composites. The particle size has a great effect on the flammability of the EVA/ATH composites. ATH with smaller particle size can increase the LOI value and improve the UL-94 flammability of the composites.
Co-reporter:Liangbin Li
Journal of Polymer Science Part B: Polymer Physics 2006 Volume 44(Issue 8) pp:1188-1198
Publication Date(Web):28 FEB 2006
DOI:10.1002/polb.20775
The crystallization behaviors of isotactic polypropylene (iPP) and its blends with thermoelastomers have been investigated with in situ X-ray scattering and optic microscopy. At quiescent condition, the crystallization kinetics of iPP is not affected by the presence of elastomers; while determined by the viscosity, the differences are observed on sheared samples. With a fixed shear strain, the crystallization rate increases with increasing the shear rate. The fraction of oriented lamellar crystals in blends is higher than that in pure iPP sample, while the percentage of β phase is reduced by the presence of the elastomers. On the basis of experimental results, no direct correlation among the fraction of oriented lamellae, the percentage of β phase, and growth rate can be deduced. The evolution of the fraction of oriented lamellae supports that shear field promotes nucleation rather than growth process. Shear flow induces the formation of nuclei not only with preferring orientation but also with random orientation. The total density of nuclei, which determines the crystallization kinetics, does not control the ratio between nuclei with and without preferring orientation, which determines the fraction of oriented lamellae. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1188–1198, 2006
Co-reporter:Ling Zhang;Chunzhong Li;Rui Huang
Journal of Polymer Science Part B: Polymer Physics 2004 Volume 42(Issue 9) pp:1656-1662
Publication Date(Web):24 MAR 2004
DOI:10.1002/polb.20035
Polypropylene (PP) was modified with elastomer or CaCO3 particles of two different sizes (1 μm and 50 nm) in various volume fractions. The dispersion morphology and mechanical properties of the two systems were investigated as functions of the particle size and volume fraction of the modifier. The brittle-to-tough transition occurred when the matrix ligament thickness was less than the critical ligament thickness, which was about 0.1 μm for the PP used here, being independent of the type of modifier. At the same matrix ligament thickness, the improvement of the toughness was obviously higher with the elastomer rather than with CaCO3, but adding CaCO3 increased the modulus of PP. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1656–1662, 2004
Co-reporter:Mengting Chen, Tao Tao, Ling Zhang, Wei Gao and Chunzhong Li
Chemical Communications 2013 - vol. 49(Issue 16) pp:NaN1614-1614
Publication Date(Web):2013/01/04
DOI:10.1039/C2CC38290C
We have manufactured a highly conductive and stretchable composite by backfilling a preformed graphene/MWCNT aerogel with poly(dimethylsiloxane) (PDMS). The electrical conductivity of our product can reach 2.8 S cm−1 with only 1.3 wt% graphene/MWCNT loading, and remains constant after 100 times repeated stretching by 20% and 5000 times bending.
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