蒙脱土填充补强丁苯橡胶及对橡胶硫化特性的影响

以十八烷基三甲基溴化铵为插层处理剂改性蒙脱土。分别采用有机蒙脱土(C₁₈-MMT) 和Na-蒙脱土(Na-MMT) 填充补强丁苯橡胶, 用XRD 和TEM 对复合材料的结构进行表征。结果表明: 蒙脱土在橡胶基体中的分散取决于蒙脱土的亲油性, 亲油性越强, 蒙脱土的片层在橡胶中的分散越均匀, 完全有机化处理的蒙脱土能够被剥离成厚度为20 nm 左右的片层并均匀分散在橡胶基体中。蒙脱土的存在对橡胶的硫化反应有一定的影响, 有机蒙脱土对橡胶硫化反应有催化作用, 但不改变硫化反应的活化能; Na-蒙脱土片层阻碍了橡胶的硫化交联, 使交联反应对温度的敏感性降低, 导致表观活化能减小。有机蒙脱土填充补强丁苯橡胶, 由于提高了橡胶的交联密度, 同时有机蒙脱土具有高比表面积和滑移性, 大大提高了橡胶的机械性能, 其拉伸强度和300 %定伸应力与炭黑N330 补强橡胶相当, 而断裂伸长率较炭黑补强橡胶有大幅度的提高, 在替代炭黑作为橡胶的补强剂方面具有广泛的应用前景。      

Solar absorption and thermal emission properties of multiwall carbon nanotube/nickel oxide nanocomposite thin films synthesized by sol–gel process

Multiwall carbon nanotubes (MWCNTs)/nickel oxide (NiO) nanocomposites were successfully prepared by a sol–gel process and coated on an aluminium substrate. The MWCNTs were chemically functionalized and then added into NiO alcogels, and magnetic stirred for homogeneous dispersion into the NiO matrix solution. The morphology of the resulting nanocomposite thin films showed that the MWCNTs were embedded in the NiO nano-particle matrix, while HRTEM confirmed that the MWCNTs were surrounded by the NiO nano-particles. Raman spectra for functionalized MWCNTs displayed a red shift from the pristine MWCNTs suggesting successful purification/functionalization. The spectrum for the MWCNTs/NiO nanocomposite indicated the presence of both the TO and LO phonons of NiO, and the D and G bands of the MWCNTs. Red and blue shifts of the NiO phonons and the MWCNT phonons suggested that the vibrational properties of both materials were changed to form new nanocomposite vibrational properties. Despite unoptimized layer thickness and composition, the solar absorptance of the functionalized MWCNTs/NiO nanocomposite films was 0.84 (for a single layer). The thermal emittance at 100 °C was approximately 0.2. These results suggest that MWCNTs/NiO nanocomposite materials are suitable for solar thermal applications.     

Enhanced thermal and mechanical properties of carbon nanotube composites through the use of functionalized CNT-reactive polymer linkages and three-roll milling

We report enhanced thermal and mechanical properties of carbon nanotube (CNT) composites achieved through the use of functionalized CNTs-reactive polymer linkages and three-roll milling. CNTs were functionalized with carboxyl groups and dispersed in a polymer containing an epoxide group resulting in a chemical reaction. To maximize CNT dispersion for practical usage, entangled CNTs are separated and then evenly dispersed within the polymer matrix using three horizontally positioned rotating rolls that apply a strong shear force to the composite. Consequently, accompanying with thermal stability, elastic modulus and storage modulus of such functionalized CNT/polymer composites were increased by 100% and 500% that of the untreated epoxy polymer.     

The role of functionalized carbon nanotubes in a PA6/LCP blend

Multi-walled carbon nanotubes (MWCNTs) were carboxyl-functionalized in order to improve their dispersion in a polymer matrix. The carboxyl-functionalized MWCNTs (i.e., MWCNT-COOH) were added into a blend matrix consisting of polyamide 6 (PA6) and liquid crystalline polymer (LCP) (PA6:LCP = 80:20 in weight) to make ternary composites. The effects of MWCNT-COOH on the rheological, physical, morphological, thermal, mechanical, and electrical properties of the ternary composites have been examined systematically. The dispersion of MWCNTs in the polymer matrix and their interactions with the polymers (i.e., PA6 and LCP) were found to be the most important factors affecting all properties. The functionalization of MWCNTs resulted in the significant improvement in their dispersion in the polymer matrix and largely enhanced the interactions of MWCNTs with the polymer matrix. The functionalized MWCNTs acted not only as reinforcement fillers but also as a compatibilizer that could enhance the interfacial adhesion between PA6 and LCP. Interestingly, the packing density of the polymer matrix was greatly increased by adding MWCNT-COOH.     

Surface modification of multi-walled carbon nanotubes using 3-aminopropyltriethoxysilane

Multi-walled carbon nanotubes (MWCNTs) were functionalized via oxidation with a mixture of concentrated sulfuric acid and nitric acid. Thus functionalized nanotubes (f-MWCNTs) were silanized using a coupling agent, 3-Aminopropyltriethoxysilane (3-APTES). The f-MWCNTs and the reaction product of f-MWCNTs and 3-APTES (APTES–MWCNTs) were characterized by Fourier Transform Infrared Spectroscopy, Energy Dispersion Spectroscopy, Scanning Electron Microscopy, and Transmission Electron Microscopy. The results indicate the attachment of silane molecules on the surface of the functionalized MWCNTs. This silanization method allows for the improvement of the chemical compatibility of MWCNTs with specific polymers for application in nanotube-based polymer matrix composites.     

The relationship of crystallization behavior,mechanical properties,and morphology of polypropylene nanocomposite fibers

This study aimed at the fabrication of lightweight and high performance nanocomposite fibers. Polypropylene/multiwalled carbon nanotubes (PP/MWCNTs) nanocomposite fibers (0–5 wt% of MWCNTs) were prepared via melt spinning process. The MWCNTs were dispersed in the dispersing agent before mixing with PP powder. After mixing, the dispersing agent was removed. Then the nanocomposites were spun into fibers. The fibers were spun and stretched with 7.5 draw ratios. Crystallization behavior and thermal properties of PP/MWCNTs nanocomposite fibers were studied using the differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA). The DSC curves of PP/MWCNTs nanocomposite fibers showed the crystallization peak at a temperature higher than that of neat PP fibers. These results revealed that the MWCNTs acted as nucleating sites for PP crystallization. The additions of MWCNTs into PP leaded to an increase in both crystallization temperature and crystallization enthalpy. However, no significant changes in the melting temperatures of the PP nanocomposites were detected. Degradation temperature of samples obtained from the TGA curves showed increase thermal degradation behavior for the PP/MWCNTs with the content of MWCNTs. It was found that the increase of tensile strength and modulus corresponded well with the increase of crystallinity of the composite fibers.     

Multi-Wall Carbon Nanotubes/Styrene Butadiene Rubber (SBR) Nanocomposite

A floating catalyst chemical vapor deposition (FC-CVD) method was designed and fabricated to produce high-quality and -quantity carbon nanotubes. The design parameters like the hydrogen flow rate; reaction time and reaction temperature were optimized to produce high yield and purity of Multi-Wall Carbon Nanotubes (MWCNTs). Multi-Walled Carbon Nanotubes (MWNTs) were used to prepare natural rubber (NR) nanocomposites. Our first efforts to achieve nanostructures in MWNTs/styrene butadiene rubber (SBR) nanocomposites were formed by incorporating carbon nanotubes in a polymer solution and subsequently evaporating the solvent. Using this technique, nanotubes can be dispersed homogeneously in the NR matrix in an attempt to increase the mechanical properties of these nanocomposites. The properties of the nanocomposites such as tensile strength, tensile modulus, elongation at break and hardness were studied. Using different percentages of carbon nanotubes from 1 wt% to 10 wt%, several nanocomposites samples were fabricated. Significant improvements in the mechanical properties of the resulting nanocomposites showed almost 10% increase in the Young's modulus for 1 wt% of CNTs and up to around 200% increase for 10 wt% of CNTs.     

Carbon black–clay hybrid nanocomposites based upon EPDM elastomer

The present study explored the effect of nanoclay on the properties of the ethylene–propylene–diene rubber (EPDM)/carbon black (CB) composites. The nanocomposites were prepared with 40 wt% loading of fillers, where the nanoclay percentage was kept constant at 3 wt%. As the modified nanoclay contains the polar groups and the EPDM matrix is nonpolar, a polar rubber oil extended carboxylated styrene butadiene rubber (XSBR), was used during the preparation of nanocomposites to improve the compatibility. Primarily the nanoclay was dispersed in XSBR by solution mixing followed by ultrasonication. After that EPDM-based, CB–clay hybrid nanocomposites, were prepared in a laboratory scale two roll mill. The dispersion of the different nanoclay in the EPDM matrix was observed by wide-angle X-ray diffraction (WAXD) and high resolution transmission electron microscopy. It was found that the mechanical properties of the hybrid nanocomposites were highly influenced by the dispersion and exfoliation of the nanoclays in the EPDM matrix. Thermo gravimetric analysis, scanning electron microscopy and dynamic mechanical thermal analysis was carried out for each nanocomposite. Among all the nanocomposites studied, the thermal and mechanical properties of Cloisite 30B filled EPDM/CB nanocomposite were found to be highest.     

水相悬浮聚合制备MWCNTs/PAN复合微球及其电纺纤维

先用Fenton试剂（过氧化氢/硫酸亚铁）对多壁碳纳米管进行改性处理（-fMWCNTs）,再通过水相悬浮聚合法制备了多壁碳纳米管/聚丙烯腈（-fMWCNTs/PAN）复合微球,用静电纺丝技术制备了-fMWCNTs/PAN复合纤维膜。通过扫描电镜（SEM）、热重分析仪（TGA）和万能试验机研究了-fMWCNTs对电纺纤维...     

Concise route to styryl-modified multi-walled carbon nanotubes for polystyrene matrix and enhanced mechanical properties and thermal stability of composite

Effective functionalization of multi-walled carbon nanotubes (MWCNTs) with styryl group was carried out via the esterification reaction of the carboxylate salt of carbon nanotubes and 4-vinylbenzyl chlorides in toluene. The functionalized MWCNTs were characterized through FTIR and Raman spectra to confirm the styryl groups covalently connected to the surface of MWCNTs. The weight loss of functionalized moieties determined by thermogravimetry-differential scanning calorimertry analysis is around 36%. Nanotube-reinforced polystyrene were fabricated by mixing functionalized MWCNTs and polystyrene. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that the functionalized nanotubes had a better dispersion than the unfunctionalized MWCNTs in the matrix. Moreover, styryl-modified MWCNTs/PS nanocompsite presented obvious improvements in mechanical properties and thermal stability.     

Structure and properties of fibrillar silicate/SBR composites by direct blend process

Silicate attapulgite(AT)/Styrene Butadiene rubber (SBR) composites with excellent properties and low cost were first prepared from a direct blending process (including polymer melt blending and emulsion co-coagulation). The structure and properties of above composites were carefully investigated. It was found that most AT separated into dispersed units with diameters less than 100 nm in SBR by the direct blend process. However, a few dispersion units as large as 0.2–0.5 m and a clear network structure of dispersion units in SBR was observed by TEM, SEM and RPA. AT can be purified, but purified AT cannot be easily dispersed in the rubber matrix by polymer melt blending. Siliane coupling agent Si69 can improve the dispersion of AT and enhance the chemical interfacial adhesion. At the same loading, AT (pretreated with Si69) was found to have better reinforcing effect on SBR than carbon black SRF with particle size 60–100 nm and even than N330 with particle size 26–30 nm to some extent. Meanwhile, the cost of AT/SBR composites is pretty low.     

Morphological and mechanical properties of bile salt modified multi-walled carbon nanotube/poly(vinyl alcohol) nanocomposites

Non-covalently functionalized carbon nanotubes are more attractive for multifunction composites because they preserve nearly all the nanotubes’ intrinsic properties and enhance the electroconductivity of polymer composites. However, It is seldom reported that they make dramatic improvement in mechanical properties. In this paper we have successfully prepared a poly(vinyl alcohol) (PVA) nanocomposite with a non-covalently functionalized carbon nanotube (DOC-MWNTs) using a simple method, which achieve a significant enhancement in mechanical properties. The tensile modulus and tensile yield strength of the PVA composite film containing 5 wt% DOC-MWNTs increased by 140% and 65%, respectively, comparing to the pure PVA film. FT-IR, TEM, SEM, and DSC were used to investigate the MWNTs and PVA/MWNTs nanocomposites. The results show that the separately dispersed DOC-MWNTs filler throughout the PVA matrix and the strong adhesion between the DOC-MWNTs filler and the PVA matrix are responsible for the significant reinforcement of the mechanical properties of the composite prepared.     

Dispersion of multi-walled carbon nanotubes in biodegradable poly(butylene succinate) matrix

This communication describes the preparation, characterization and properties of biodegradable poly(butylene succinate) (PBS)/multi-walled carbon nanotubes (MWCNTs) nanocomposite. Nanocomposite was prepared by melt-blending in a batch mixer and the amount of MWCNTs loading was 3 wt%. State of dispersion-distribution of the MWCNTs in the PBS matrix was examined by scanning and transmission electron microscopic observations that revealed homogeneous distribution of stacked MWCNTs in PBS matrix. The investigation of the thermomechanical behavior was performed by dynamic mechanical thermal analysis. Results demonstrated substantial enhancement in the mechanical properties of PBS, for example, at room temperature, storage flexural modulus increased from 0.64 GPa for pure PBS to 1.2 GPa for the nanocomposite, an increase of about 88% in the value of the elastic modulus. The tensile modulus and thermal stability of PBS were moderately improved after nanocomposite preparation with 3 wt% of MWCNTs, while electrical conductivity of neat PBS dramatically increased after nanocomposite formation. For example, the in plane conductivity increased from 5.8 x 10(-9) S/cm for neat PBS to 4.4 x 10(-3) for nanocomposite, an increase of 10(6) fold in value of the electrical conductivity.     

Effect of multiwalled carbon nanotubes on the crystallization and dielectric properties of BP-PEN nanocomposites

In this work, polymer-based nanocomposite films formed from biphenol poly(arylene ether nitrile) (BP-PEN) and multiwalled carbon nanotubes (MWCNTs) were successfully prepared by the solution casting method combined with continuous ultrasonic dispersion technology. The micromorphology, thermal, mechanical and dielectric properties of the nanocomposite films were investigated in detail. Non-isothermal crystallization behavior studies indicate that the presence of MWCNTs enhances the crystallization of BP-PEN in the nanocomposites, which is consistent with the XRD analysis. Most importantly, it could be observed that the film containing 0.8 wt% MWCNTs reached the maximum crystallinity. Although, incorporation of MWCNTs did not obviously increase the mechanical of the films, all the nanocomposite films still exhibited excellent mechanical strength. The SEM micrographs of the nanocomposite films showed that the MWCNTs were uniformly coated by BP-PEN crystals, and indicating significantly improved nucleation ability of MWCNTs for polymer crystallization.     

Preparation,characterization and properties of polycaprolactone diol-functionalized multi-walled carbon nanotube/thermoplastic polyurethane composite

Multi-walled carbon nanotubes (MWCNTs) were chemically functionalized to prepare thermoplastic polyurethane (PU) composites with enhanced properties. In order to achieve a high compatibility of functionalized MWCNTs with the PU matrix, polycaprolactone diol (PCL), as one of PU’s monomers, was selectively grafted on the surface of MWCNTs (MWCNT–PCL), while carboxylic acid groups functionalized MWCNTs (MWCNT–COOH) and raw MWCNTs served as control. Both MWCNT–COOH and MWCNT–PCL improved the dispersion of MWCNTs in the PU matrix and interfacial bonding between them at 1 wt% loading fraction. The MWCNT–PCL/PU composite showed the greatest extent of improvement, where the tensile strength and modulus were 51.2% and 33.5% higher than those of pure PU respectively, without sacrificing the elongation at break. The considerable improvement in both mechanical properties and thermal stability of MWCNT–PCL/PU composite should result from the homogeneous dispersion of MWCNT–PCL in the PU matrix and strong interfacial bonding between them.     

Effect of dispersion of MWCNTs on the static and dynamic mechanical behavior of epoxy matrix nanocomposites

In this investigation, specimens of MWCNT-epoxy nanocomposites were prepared by two different dispersion methods including the use of ultrasonication, and high speed shear mixing. The dispersion degree between MWCNT and polymer resin was analyzed after completing the curing reaction, by scanning electron microscopy. The effect of the nanotubes dispersion achieved on the properties of the manufactured nanocomposite was analyzed through static three point bending tests and dynamic mechanical thermal analysis. Interesting results concerning the dispersion effect of MWCNTs added to the polymer matrix on the storage and loss moduli as well as on tanδ and T _g values of the specimens manufactured by the sonication and high speed shear mixing methods were derived.     

Strain sensing in polymer/carbon nanotube composites by electrical resistance measurement

In this work multiwall carbon nanotubes (MWCNTs) dispersed in a polymer matrix have been used for strain sensing of the resulting nanocomposite under tensile loading. This was achieved by measuring the relative electrical resistance change (ΔR/R₀) in conductive polyvinylidenefluoride (PVDF)/MWCNTs nanocomposites prepared by melt-mixing with varying filler content from 0.5 wt.% to 8 wt.%. Two main parameters were systematically studied. The PVDF/MWCNTs mixing procedure that results in a successful MWCNTs dispersion, and the effect of MWCNTs content on material’s sensing behaviour. The samples were subjected to tensile loading and the longitudinal strain was monitored together with the longitudinal electrical resistance. The results showed that MWCNTs dispersed in insulating PVDF matrix have the potential to be used as a sensitive network to monitor the strain levels in polymer/carbon nanotube nanocomposites as the deformation level of each sample was being reflected by the resistance changes.     

Incorporation of liquid-like multiwalled carbon nanotubes into an epoxy matrix by solvent-free processing

Covalent attachment of 2,2'-(ethylenedioxy)-diethylamine to multiwalled carbon nanotubes (MWCNTs) produced amino-functionalized MWCNTs which behaved like liquids at ambient temperature. These liquid-like MWCNTs (l-MWCNTs) could be homogeneously dispersed and chemically embedded in an epoxy matrix by solvent-free processing. In contrast, solid MWCNTs (s-MWCNTs) functionalized by 1,8-diaminooctane were poorly dispersed in epoxy although they possess chemical structures and functionalization comparable to l-MWCNTs. An epoxy composite filled with pristine MWCNTs (p-MWCNTs) was also fabricated in the absence of a solvent at the same loading for comparison. The molecular level coupling of l-MWCNTs and epoxy provided significant improvements in overall mechanical properties relative to those composites containing p-MWCNTs and s-MWCNTs. The Young's modulus, storage modulus, tensile strength, failure strain and toughness of neat epoxy were increased by 28.4, 23.8, 22.9, 24.1 and 66.1%, respectively, by adding 0.5?wt% of l-MWCNTs. Thus, functionalized carbon nanotubes in liquid form contributed to better dispersion and superior interfacial bonding with the epoxy matrix, thereby facilitating greater mechanical reinforcement efficiency.     

Study on novel poly (vinyl pyrrolidone) doped MWCNTs/polyrhodanine nanocomposites: Synthesis,characterization, and thermal performance

In this paper, poly (vinyl pyrrolidone) (PVP) doped multiwall carbon nanotubes (MWCNTs/polyrhodanine), were synthesized through one-step chemical oxidative polymerization of rhodanine monomers on the surface-modified carbon nanotubes. Characterization of MWCNTs/polyrhodanine was conducted by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and EDX spectrum analyses in which the results confirmed the successful formation of MWCNTs/polyrhodanine. In addition, to investigate the thermal properties of samples, thermogravimetric analysis (TGA) was employed, and results exhibited significant improvement in the nanocomposite thermal stability due to the addition of MWCNTs with reinforcement effect in polymer matrix.     

Effect of nanoclays on physico-mechanical properties and adhesion of polyester-based polyurethane nanocomposites: structure–property correlations

Polyester–polyurethane nanocomposites based on unmodified and modified montmorillonite clays were compared in terms of their morphology, mechanical, thermal, and adhesive properties. Excellent dispersion of the modified nanoclay in polymer with 3 wt% loading was confirmed from X-ray diffraction, and low-, and high-magnification transmission electron micrographs. The properties of the clay-reinforced polyurethane nanocomposites were a function of nature and the content of clay in the matrix. The nanocomposite containing 3 wt% modified clay exhibits excellent improvement in tensile strength (by ~100%), thermal stability (20 °C higher), storage modulus at 25 °C (by ~135%), and adhesive properties (by ~300%) over the pristine polyurethane.