首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The electrical properties in polymer/carbon nanotube (CNT) nanocomposites are governed not only by the degree of dispersion but also to a greater extent on the aspect ratio of the CNTs in the final composites. Melt‐mixing of polymer and CNTs at high shear rate usually breaks the CNTS that lowers the aspect ratio of the nanotubes. Thus, homogeneous dispersion of CNTs while retaining the aspect ratio is a major challenge in melt‐mixing. Here, we demonstrate a novel method that involves melt‐blending of acrylonitrile‐butadiene‐styrene (ABS) and in situ polymerized polystyrene (PS)/multiwalled CNT (MWCNT) nanocomposites, to prepare electrically conducting ABS/MWCNT nanocomposites with very low CNT loading than reported. The rationale behind choosing PS/MWCNT as blending component was that ABS is reported to form miscible blend with the PS. Thus, (80/20 w/w) ABS/(PS/MWCNT) nanocomposites obtained by melt‐blending showed electrical conductivity value ≈1.27 × 10?6 S cm?1 at MWCNT loading close to 0.64 wt %, which is quite lower than previously reported value for ABS/MWCNT system prepared via solution blending. Scanning electron microscopy and differential scanning calorimetry analysis indicated the formation of homogenous and miscible blend of ABS and PS. The high temperature (100°C) storage modulus of ABS (1298 MPa) in the nanocomposites was increased to 1696 MPa in presence of 0.64 wt % of the MWCNT. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

2.
A method is reported that involves the bulk polymerization of styrene monomer in the presence of multi-wall carbon nanotubes (MWCNTs) and polystyrene (PS) beads, for the preparation of MWCNT/PS conducting composites with a significantly lower (0.08 wt.% MWCNT) percolation threshold than previously reported. Thus, the conductivities of 7.62 × 10−5 and 1.48 × 10−3 S cm−1 were achieved in the MWCNT/PS composites through homogeneous dispersion of 0.08 and 0.26 wt.% CNTs, respectively in the in situ polymerized PS region by using 70 wt.% PS beads during the polymerization. The extent of dispersion and location of the MWCNTs in the PS matrix has been investigated with a scanning and transmission electron microscopy. The conductivity of the composites was increased with increasing wt.% of the PS beads at a constant CNT loading, indicating the formation of a more continuous network structure of the CNTs in PS matrix.  相似文献   

3.
Poly(ethylene oxide) (PEO) based nanocomposites were prepared by the dispersion of multiwall carbon nanotubes (MWCNTs) in aqueous solution. MWCNTs were added up to 4 wt % of the PEO matrix. The dynamic viscoelastic behavior of the PEO/MWCNT nanocomposites was assessed with a strain‐controlled parallel‐plate rheometer. Prominent increases in the shear viscosity and storage modulus of the nanocomposites were found with increasing MWCNT content. Dynamic and isothermal differential scanning calorimetry studies indicated a significant decrease in the crystallization temperature as a result of the incorporation of MWCNTs; these composites can find applications as crystallizable switching components for shape‐memory polymer systems with adjustable switching temperatures. The solid‐state, direct‐current conductivity was also enhanced by the incorporation of MWCNTs. The dispersion level of the MWCNTs was investigated with scanning electron microscopy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

4.
Clay-assisted dispersion of MWCNT has emerged as a novel alternative to its conventional modification. The report deals with preparation of MWCNT/hectorite hybrid (HMH) by dry grinding method and its utilization for the reinforcement of styrene butadiene rubber (SBR). Significant improvement in tensile strength (210%) and elongation at break (42%) of SBR/HMH nanocomposite at 0.7 wt.% HMH shows its superior reinforcing efficiency. Comparison with individual fillers confirms significant synergy. Best thermal stability and dielectric response are achieved at 0.3 and 0.7 wt.% filler contents respectively. Improved properties of the nanocomposites are ascribed to enhanced level of filler dispersion and polymer-filler interaction.  相似文献   

5.
In this work, nanocomposites with simultaneous dispersion of multiwalled carbon nanotubes (MWCNT) and montmorillonite clays in an epoxy matrix were prepared by in situ polymerization. A high energy sonication was employed as the dispersion method, without the aid of solvents in the process. The simultaneous dispersion of clays with carbon nanotubes (CNT) in different polymeric matrices has shown a synergic potential of increasing mechanical properties and electrical conductivity. Two different montmorillonite clays were used: a natural (MMT‐Na+) and an organoclay (MMT‐30B). The nanocomposites had their electrical conductivity (σ) and dielectric constant (εr) measured by impedance spectroscopy. The sharp increase in electrical conductivity was found between 0.10 and 0.25 wt% of the MWCNTs. Transmission electron microscopy (TEM) of the samples showed a lower tendency of MWCNT segregation on the MMT‐30B clay surface, which is connected to intercalation/exfoliation in the matrix, that generates less free volume available for MWCNTs in the epoxy matrix. Data from electrical measurement showed that simultaneously adding organoclay reduces the electrical conduction in the nanocomposite. Moreover, conductivity and permittivity dispersion in low frequency suggest agglomeration of nanotubes surrounding the natural clay (MMT‐Na+) particles, which is confirmed by TEM. POLYM. COMPOS., 37:1603–1611, 2016. © 2014 Society of Plastics Engineers  相似文献   

6.
A series of polyimide‐based nanocomposites containing polyimide‐grafted multi‐walled carbon nanotubes (PI‐g MWCNTs) and silane‐modified ceramic (aluminium nitride (AlN)) were prepared. The mechanical, thermal and electrical properties of hybrid PI‐g MWCNT/AlN/polyetherimide nanocomposites were investigated. After polyimide grafting modification, the PI‐g MWCNTs showed good dispersion and wettability in the polyetherimide matrix and imparted excellent mechanical, electrical and thermal properties. The utilization of the hybrid filler was found to be effective in increasing the thermal conductivity of the composites due to the enhanced connectivity due to the high‐aspect‐ratio MWCNT filler. The use of spherical AlN filler and PI‐g MWCNT filler resulted in composite materials with enhanced thermal conductivity and low coefficient of thermal expansion. Results indicated that the hybrid PI‐g MWCNT and AlN fillers incorporated into the polyetherimide matrix enhanced significantly the thermal stability, thermal conductivity and mechanical properties of the matrix. Copyright © 2012 Society of Chemical Industry  相似文献   

7.
Foaming behavior of poly(methyl methacrylate) (PMMA)/multi‐walled carbon nanotubes (MWCNTs) nanocomposites and thermally‐insulating, electrical, and mechanical properties of the nanocomposite foams are investigated. PMMA/MWCNT nanocomposites containing various amounts of MWCNTs are first prepared by combining solution and melt blending methods, and then foamed using CO2. The foaming temperature and MWCNT content are varied for regulating the structure of PMMA/MWCNT nanocomposite foams. The electrical conductivity measurement results show that MWCNTs have little effect on the electrical conductivity of foams with large expansion ratio. Thermal conductivities of both solid and foamed PMMA/MWCNT nanocomposites are measured to evaluate their thermally insulating properties. The gas conduction, solid conduction, and thermal radiation of the foams are calculated for clarifying the effects of cellular structure and MWCNT content on thermal insulation properties. The result demonstrates that MWCNTs endowed foams with enhanced thermal insulation performance by blocking thermal radiation. Moreover, the compressive testing shows that MWCNTs improve the compressive strength and rigidity of foams. This research is essential for optimizing environmentally friendly thermal insulation nanocomposite foams with enhanced thermal‐insulation and compressive mechanical properties.  相似文献   

8.
Nanocomposites of blends of polymethylmethacrylate (PMMA) and poly(styrene‐co‐acrylonitrile) (SAN) with multi‐walled carbon nanotubes (MWCNTs) were prepared by melt mixing in a twin‐screw extruder. The dispersion state of MWCNTs in the matrix polymers was investigated using transmission electron microscopy. Interestingly enough, in most of the nanocomposites, the MWCNTs were observed to be mainly located at SAN domains, regardless of the SAN compositions in the PMMA/SAN blend and of the processing method. One possible reason for this morphology may be the π–π interactions between MWCNTs and the phenyl ring of SAN. The shift in G‐band peak observed in the Raman spectroscopy may be the indirect evidence proving these interactions. The percolation threshold for electrical conductivity of PMMA/SAN/MWCNT nanocomposites was observed to be around 1.5 wt %. Nanocomposites with PMMA‐rich composition showed higher electrical conductivity than SAN‐rich nanocomposites at a fixed MWCNT loading. The dielectric constant measurement also showed composition‐dependent behavior. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

9.
A cryogenic ball‐milling process to produce polymer/CNT nanocomposites was investigated. Linear low density polyethylene was used as the matrix material and 1 wt % of multiwalled carbon nanotubes (MWCNT) was used as reinforcement. The influence of the milling time and balls size was evaluated. The morphology of the nanocomposite and the degree of dispersion of the MWCNTs were studied using scanning electron microscopy (SEM), visual inspection, and light transmission microscopy; ropes as well as aggregates of MWCNTs were observed, and there was evidence of wetting of the nanotubes by the matrix polymer. An increase of up to 28% in the elastic modulus (determined by tensile testing) with respect to the matrix was obtained. Differential scanning calorimetry (DSC) analysis showed evidence of increase in the degree of crystallization, a result of the nucleating capability of the carbon nanotubes in the matrix. The degradation temperature of the nanocomposites does not show significant variations with respect to the unfilled polymer. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers  相似文献   

10.
This study investigated the correlation between the electrical conductivity and the micro and nanomorphology of multiwalled carbon nanotubes (MWCNTs)/epoxy nanocomposites with and without the inorganic fillers montmorillonite (MMT), sepiolite and calcium carbonate (CaCO3). The nanocomposites were prepared by dispersing the MWCNT and fillers through ultrasonication directly in the resin or solvent. For nanocomposites without fillers, the compositions prepared with solvent demonstrated higher electrical conductivities, which correlate with a microscale morphology formed by networks of highly interconnected MWCNT agglomerates. The addition of MMT induced a deleterious effect on the electrical conductivity of the nanocomposites since this filler hinders the formation of MWCNT agglomerate networks. The effect of sepiolite on electrical conductivity is also negative, but in this case, nonmorphological effects are likely of greater importance. The addition of CaCO3 improved the electrical conductivity of the binary nanocomposites under specific conditions. For this filler, a synergic effect was achieved for the composition prepared with solvent, which resulted in an approximately sixfold increase in electrical conductivity relative to the nanocomposite without filler.  相似文献   

11.
Poly (o‐anisidine) (POA) ‐ Multi‐walled carbon nanotube (MWCNT) nanocomposites were synthesized by simple in‐situ chemical oxidative technique. Synthesized nanocomposites were characterized for their structure, morphology, thermal and electrical properties. Spectral studies indicated the presence of interactions between poly (o‐anisidine) and the surface of MWCNTs. Conductivity of 2.82 × 10−2 S cm−1 was obtained for POA‐MWCNT nanocomposite sample containing 21.2% wt. of POA. POA‐MWCNT nanocomposites thus synthesized were incorporated into epoxy based coating formulation and its anticorrosion property was studied. The coatings were also characterized by physicochemical as well as physicomechanical studies. The aim of this study was to develop a facile method for the eco‐friendly synthesis of fillers having better dispersing properties for coating having superior corrosion protective properties. POLYM. COMPOS., 36:1477–1485, 2015. © 2014 Society of Plastics Engineers  相似文献   

12.
To shield undesirable electromagnetic waves caused by electronic devices and simultaneously resolve the flame safety of the electronic components, an electromagnetic interference (EMI) shielding material with excellent flame‐retardant properties is urgently needed. The synergistic effect of the intumescent flame retardant (IFR) and multiwalled carbon nanotubes (MWCNTs) for polystyrene (PS) nanocomposites prepared by melt blending was investigated. The results show that addition of certain amounts of IFRs facilitated the dispersion of MWCNTs in the PS matrix, and the percolation threshold of the MWCNTs in the PS matrix also decreased from 1.67 ± 0.05 to 1.29 ± 0.04 wt %. Moreover, the EMI shielding efficiencies (SEs) of the PS–MWCNT–IFR composites were consistently higher than those of the PS–MWCNT composites without the addition of the IFRs at the same MWCNT content; this indicated that the synergistic effect of the MWCNTs and IFRs effectively improved the EMI SE of the PS–MWCNT–IFR composites. Furthermore, the limiting oxygen index (LOI) testing results show that the LOI values of the PS–MWCNT composites were consistently higher than 27%; this indicated that the PS–MWCNT composites effectively met the needs of flame safety; this indicated that the PS–MWCNT–IFR composite is a novel and promising candidate for an ideal EMI shielding material with excellent flame‐retardant properties for today's electronic devices. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45088.  相似文献   

13.
Influences of different nanocomposite loadings in poly(lactic acid) (PLA) matrix on resulting hardness and elasticity were examined in nanoindentation experiments. The following study was focused on the nanomechanical properties of PLA reinforced with graphene nanoplatelets (GNPs) and multiwall carbon nanotubes (MWCNTs) by using Berkovich type pyramidal nanoindenter. A masterbatch strategy was developed to disperse GNP and MWCNT into PLA by melt blending. Young's modulus and nanohardness of as-prepared nanocomposites were characterized as a function of the graphene and carbon nanotubes loading. The nanoindentation analysis reveals that these carbon nanofillers improve the mechanical stability of the nanocomposites GNP/PLA, MWCNT/PLA, and GNP/MWCNT/PLA. That improvement of mechanical properties strongly depends on the fillers content. It was found that the best mechanical performance was achieved for the compound having 6 wt % graphene and 6 wt % MWCNTs in the PLA matrix. The received values for nanohardness and Young's modulus are among the highest reported for PLA-based nanocomposites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47260.  相似文献   

14.
A spray drying approach has been used to prepare polyurethane/multiwalled carbon nanotube (PU/MWCNT) composites. By using this method, the MWCNTs can be dispersed homogeneously in the PU matrix in an attempt to improve the mechanical properties of the nanocomposites. The morphology of the resulting PU/MWCNT composites was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM observations illustrate that the MWCNTs are dispersed finely and uniformly in the PU matrix. X‐ray diffraction results indicate that the microphase separation structure of the PU is slightly affected by the presence of the MWCNTs. The mechanical properties such as tensile strength, tensile modulus, elongation at break, and hardness of the nanocomposites were studied. The electrical and the thermal conductivity of the nanocomposites were also evaluated. The results show that both the electrical and the thermal conductivity increase with the increase of MWCNT loading. In addition, the percolation threshold value of the PU composites is significantly reduced to about 5 wt % because of the high aspect ratio of carbon nanotubes and exclusive effect of latex particles of PU emulsion in dispersion. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

15.
Here, we demonstrate an easy method for the preparation of highly electrically conductive polycarbonate (PC)/multiwalled carbon nanotubes (MWCNTs) nanocomposites in the presence of poly(butylene terephthalate) (PBT). In the presence of MWCNTs, PC and PBT formed a miscible blend, and the MWCNTs in the PC matrix were uniformly and homogeneously dispersed after the melt mixing of the PC and PBT–MWCNT mixture. Finally, when the proportion of the PC and PBT–MWCNT mixture in the blend/MWCNT nanocomposites was changed, an electrical conductivity of 6.87 × 10?7 S/cm was obtained in the PC/PBT–MWCNT nanocomposites at an MWCNT loading as low as about 0.35 wt %. Transmission electron microscopy revealed a regular and homogeneous dispersion and distribution of the MWCNTs and formed a continuous conductive network pathway of MWCNTs throughout the matrix phase. The storage modulus and thermal stability of the PC were also enhanced by the presence of a small amount of MWCNTs in the nanocomposites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

16.
Today, we stand at the threshold of exploring carbon nanotube (CNT) based conducting polymer nanocomposites as a new paradigm for the next generation multifunctional materials. However, irrespective of the reported methods of composite preparation, the use of CNTs in most polymer matrices to date has been limited by challenges in processing and insufficient dispersability of CNTs without chemical functionalization. Thus, development of an industrially feasible process for preparation of polymer/CNT conducting nanocomposites at very low CNT loading is essential prior to the commercialization of polymer/CNT nanocomposites. Here, we demonstrate a process technology that involves in situ bulk polymerization of methyl methacrylate monomer in the presence of multi‐wall carbon nanotubes (MWCNTs) and commercial poly(methyl methacrylate) (PMMA) beads, for the preparation of PMMA/MWCNT conducting nanocomposites with significantly lower (0.12 wt% MWCNT) percolation threshold than ever reported with unmodified commercial CNTs of similar qualities. Thus, a conductivity of 4.71 × 10?5 and 2.04 × 10?3 S cm?1 was achieved in the PMMA/MWCNT nanocomposites through a homogeneous dispersion of 0.2 and 0.4 wt% CNT, respectively, selectively in the in situ polymerized PMMA region by using 70 wt% PMMA beads during the polymerization. At a constant CNT loading, the conductivity of the composites was increased with increasing weight percentage of PMMA beads, indicating the formation of a more continuous network structure of the CNTs in the PMMA matrix. Scanning and transmission electron microscopy studies revealed the dispersion of MWCNTs selectively in the in situ polymerized PMMA phase of the nanocomposites. Copyright © 2012 Society of Chemical Industry  相似文献   

17.
In order to investigate whether the particle sizes of inorganic additives in polymer have an influence on the flame‐retardant and other properties of the polymer, five types of Mg3Al–CO3 layered double hydroxide (LDHs) with particle diameters of 80–100, 200–350, 500–550, 550–600, and 700–900 nm were synthesized using a hydrothermal method. The obtained Mg3Al–CO3 LDHs were treated using the aqueous miscible organic solvent treatment method to give highly dispersed platelets in Polypropylene (PP). The thermal stability, flame retardancy, and mechanical properties of the PP/AMO–LDH nanocomposites were investigated systematically. The results showed that the thermal stability and flame retardancy of PP could be improved after incorporating AMO–LDHs. The temperature at 50% weight loss (T0.5) of PP/LDH (700–900 nm) nanocomposites with a LDH loading of 15 wt % was increased by 57 °C. When the LDHs loading was 40 wt %, the peak heat release rate (PHRR) of the PP/LDH nanocomposites with small LDHs particle sizes (<350 nm) was decreased by ca. 58%. The limiting oxygen index was increased by 5% for PP/LDH (80–100 nm) nanocomposites. The response surface regression results also indicated that both LDH particle size and loading have influence on PHRR, heat release capacity, tensile strength, and elongation at break. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46204.  相似文献   

18.
In this work, electrical conductivity and thermo‐mechanical properties have been measured for carbon nanotube reinforced epoxy matrix composites. These nanocomposites consisted of two types of nanofillers, single walled carbon nanotubes (SW‐CNT) and electrical grade carbon nanotubes (XD‐CNT). The influence of the type of nanotubes and their corresponding loading weight fraction on the microstructure and the resulting electrical and mechanical properties of the nanocomposites have been investigated. The electrical conductivity of the nanocomposites showed a significantly high, about seven orders of magnitude, improvement at very low loading weight fractions of nanotubes in both types of nanocomposites. The percolation threshold in nanocomposites with SW‐CNT fillers was found to be around 0.015 wt % and that with XD‐CNT fillers around 0.0225 wt %. Transmission optical microscopy of the nanocomposites revealed some differences in the microstructure of the two types of nanocomposites which can be related to the variation in the percolation thresholds of these nanocomposites. The mechanical properties (storage modulus and loss modulus) and the glass transition temperature have not been compromised with the addition of fillers compared with significant enhancement of electrical properties. The main significance of these results is that XD‐CNTs can be used as a cost effective nanofiller for electrical applications of epoxy based nanocomposites at a fraction of SW‐CNT cost. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

19.
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  相似文献   

20.
The effect of CNT orientation on electrical and mechanical properties is presented on the example of an ultra-high filler loaded multi-walled carbon nanotube (68 wt.% MWCNTs) epoxy-based nanocomposite. A novel manufacturing method based on hot-press infiltration through a semi-permeable membrane allows to obtain both, nanocomposites with aligned and randomly oriented CNTs (APNCs and RPNCs) over a broad filler loading range of ≈10–68 wt.%. APNCs are based on low-defected, mm-long aligned MWCNT arrays grown in chemical vapour deposition (CVD) process. Electrical conductivity and mechanical properties were measured parallel and perpendicular to the direction of CNTs. RPNCs are based on both, aligned mm-long MWCNTs and randomly oriented commercial μm-long and entangled MWCNTs (Baytube C150P, and exemplarily Arkema Graphistrength C100). The piezoresistive strain sensing capability of these high-wt.% APNCs and RPNCs had been investigated towards the influence of CNT orientations. For the highest CNT fraction of 68 wt.% of unidirectional aligned CNTs a Young’s modulus of E||  36 GPa and maximum electrical conductivity of σ||  37·104 S/m were achieved.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号