橡胶基纳米复合材料研究进展

介绍了橡胶基纳米复合材料的制备方法，综述了橡胶基纳米复合材料的研究进展，提出了橡胶基纳米复合材料的发展趋势。     

Effect of organoclay on the gas barrier properties of natural rubber nanocomposites

Natural rubber nanocomposites have been prepared with organically modified montmorillonite clay. The nanocomposites have been characterized by X‐ray diffractometry and transmission electron microscopy. The gas‐barrier properties of the nanocomposites have been studied for three different gases viz., oxygen, nitrogen, and CO₂ gases. The natural rubber–organoclay composites exhibit outstanding gas‐barrier properties compared to the neat rubber. Various models have been applied to predict the decrease in permeability in nanocomposites. All other models except Bharadwaj model give low values of calculated aspect ratio. Dynamic mechanical analysis has been carried out to investigate the role of the constrained region on the permeability of the nanocomposites. The permeability decrease of the organoclay nanocomposites is found to have good qualitative correlation with the volume of the constrained region. POLYM. COMPOS.,, 2012. © 2012 Society of Plastics Engineers     

A comparison of the temperature dependence of the modulus, yield stress and ductility of nanocomposites based on high and low MW PA6 and PA66

Nanocomposites with both organically modified and unmodified silicate have been prepared by an extrusion process using low and high molecular weight grades of PA6 and a low MW grade of PA66. Mechanical properties have been tested at temperatures ranging from 20 to 120 °C. The modulus increase in all nanocomposites with organically modified nanocomposites is similar: at room temperature an increase in the modulus of approximately 10% for each wt% of silicate is found. PA66 nanocomposites display an identical normalized modulus increase as PA6 nanocomposites, while unmodified silicate nanocomposites show a smaller increase in the modulus. The yield stress also increases with the addition of layered silicate. Low MW PA6 and PA66 nanocomposites show brittle fracture behaviour at room temperature, while high MW PA6 nanocomposites are ductile. With increasing temperature all nanocomposites become ductile at a certain temperature.     

Preparation and properties of polypropylene filled with organo‐montmorillonite nanocomposites

Organo‐Montmorillonite (Org‐MMT)/maleic anhydride grafted polypropylene (PP‐g‐MAH)/polypropylene nanocomposites have been prepared by melt blending with twin‐screw extruder. The mechanical properties of the nanocomposites and the dispersion of Org‐MMT intercalated by the macromolecular chain were investigated by transmission electron microscopy and mechanical tests. The crystal properties of the nanocomposites have been tested by a differential scanning calorimeter. The thermal properties of the nanocomposites were investigated by thermo gravimetric analysis. The results show that not only the impact property but also the tensile property and the bending modulus of the system have been increased evidently by the added Org‐MMT. The Org‐MMT has been dispersed in the matrix in the nanometer scale. With the addition of the Org‐MMT, the melting point and the crystalling point of the nanocomposites increased; the total velocity of crystallization of the nanocomposites also increased. Thermal stability of the nanocomposites is increased by the filled Org‐MMT. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2875–2880, 2006     

聚苯乙烯/石墨烯纳米复合材料研究进展

综述了聚苯乙烯/石墨烯纳米复合材料制备方法的研究进展,包括溶液插层法、微球覆盖还原法、原位乳液聚合法、Pickering乳液聚合法、点击化学法、原子转移自由基法,以及聚苯乙烯/石墨烯纳米复合材料在电性能、热性能、流变性能和力学性能等方面的研究进展,并对其应用前景进行了展望。     

Electrical and mechanical properties of carbon nanotube‐epoxy nanocomposites

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     

Poly(L‐lactide)/Poly(D‐lactide)/clay nanocomposites: Enhanced dispersion,crystallization, mechanical properties,and hydrolytic degradation

Poly(L ‐lactide) (PLLA)/poly(D ‐lactide) (PDLA)/clay nanocomposites are prepared via simple melt blending method at PDLA loadings from 5 to 20 wt%. Formation of the stereocomplex crystals in the nanocomposites is confirmed by differential scanning calorimetry and wide‐angle X‐ray diffraction (WAXD). The internal structure of the nanocomposites has been established by using WAXD and transmission electron microscope analyses. The dispersion of clay in the PLLA/PDLA/clay nanocomposites can be improved as a result of increased intensity of shear during melt blending. The overall crystallization rates are faster in the PLLA/PDLA/clay nanocomposites than in PLLA/clay nanocomposite and increase with an increase in the PDLA loading up to 10 wt%; however, the crystallization mechanism and crystal structure of these nanocomposites remain unchanged despite the presence of PDLA. The storage modulus has been apparently improved in the PLLA/PDLA/clay nanocomposites with respect to PLLA/clay nanocomposite. Moreover, it is found that the hydrolytic degradation rates have been enhanced obviously in the PLLA/PDLA/clay nanocomposites than in PLLA/clay nanocomposite. POLYM. ENG. SCI., 54:914–924, 2014. © 2013 Society of Plastics Engineers     

Effect of solution concentration on the properties of nanocomposites

Though a large number of nanocomposites prepared by solution process has been reported in the literature, effect of solution concentration on properties of the nanocomposites has not been studied. In the present work, new fluorocarbon–clay nanocomposites were prepared by a solution mixing process. Characterization of the nanocomposites was done with X‐ray diffraction technique and atomic force microscopy. Effects of different rubber‐solution concentrations (5, 10, 15, 20, and 25 wt %) on the mechanical and dynamic mechanical properties of the resultant nanocomposites were investigated. Optimum properties were achieved at 20 wt % solution. The data could be explained with the help of structure of the nanocomposites and dispersion of the clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2407–2411, 2006     

The Influence of Crysnanoclay Addition on Mechanical and Thermal Properties of Thermoplastic Polyurethane Elastomeric with Polycarbonate Nanocomposites

A series of crysnanoclay-loaded thermoplastic polyurethane (TPU) elastomer/polycarbonate (PC) nanocomposites have been prepared using twin screw extruders. The physicomechanical properties such as tensile behaviors, flexural properties and impact strength of the composites have been reported. Significant improvement in tensile modulus and flexural modulus were noticed for nanocomposites. The thermal characteristics of nanocomposites have been determined by thermogravimetric analysis (TGA) techniques. Thermal degradation kinetic parameters such as energy of activation (E_a) have been calculated from TGA thermograms for the nanocomposites using three mathematical models namely; Coats–Redfern, Horowitz – Metzger and Broido's methods and the results are compared. The effect of crysnanoclay on the storage modulus (E′), loss modulus (E″), and damping factor (tan δ) as a function of temperature have been measured by dynamic mechanical analysis (DMA). The storage moduli of nanocomposites have been increased after incorporating crysnanoclay in polymer matrix.     

Electrical properties and electromagnetic interference shielding effectiveness of multiwalled carbon nanotubes‐reinforced EMA nanocomposites

Electrical and electromagnetic interference shielding effectiveness (EMI SE) properties of the ethylene methyl acrylate (EMA)/multiwalled carbon nanotube (MWNT) nanocomposites have been studied. High resolution transmission electron microscope (HRTEM) was used to validate the MWNTs dispersion state and network connections of its microstructure. The electrical resistance of the nanocomposites decreases significantly with MWNTs content. DC resistivity and AC conductivity measurement on the nanocomposite samples showed that the insulator to conductor transition took place within 10 wt% MWNTs concentration. It has been found that as MWNT concentration increased network connections improved. The EMI SE of the nanocomposites has also been investigated. The highest SE (∼20 dB) of these nanocomposites is realistic for an industrial application. EMA/MWNT nanocomposites provide sufficient intrinsic EMI shielding capability which may be hopeful for electrical and electronic applications. The morphology correlates well with the electrical and electromagnetic behavior of these nanocomposites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Effects of silver nanoparticles on thermal properties of DBSA-doped polyaniline/PVC blends

Dodecylbenzenesulfonic acid (DBSA)-doped polyaniline (PAND) has been synthesized by redoping (PANDR) and aqueous polymerization (PANDA) methods. Silver nanoparticles were incorporated into the PANDR/tetrahydrofuran solution (PANDS) and then mixed with poly (vinyl chloride) (PVC) solution to prepare PANDS/PVC nanocomposites. In the present study, effects of silver nanoparticles on thermal properties of PAND/PVC blends have been investigated by employing thermal gravimetric analysis and heat flow microcalorimetry techniques. From these results it has been observed that the thermal stability of blends have increased by increasing the concentration of PAND in blends and nanocomposites. Addition of silver nanoparticles has suppressed the dehydrochlorination process and evolution/degradation of DBSA in PANDS/PVC nanocomposites. Presence of silver nanoparticles in PAND/PVC nanocomposites has reduced the mobility of PANI chains which in turn inhibited the transfer of free radicals formed during degradation of PAND and PVC through inter-chain reactions; hence, degradation process has been slowed down and thermal stability has been improved. Embedment of silver nanoparticles has reduced thermal weight loss corresponding to polymer degradation step and attains lower heat flow level in inert atmosphere for nanocomposites in contrast to those with no nanoparticles, thereby further improving thermal stability of nanocomposites. The heats of oxidation measured for blends and nanocomposites were independent of PAND/PVC blends composition.     

Effect of Clay Types on the Mechanical,Dynamic Mechanical and Morphological Properties of Polypropylene Nanocomposites

In the present investigation Polypropylene–Maleic anhydride grafted polypropylene–organically modified MMT (PP-MAPP-OMMT) nanocomposites were prepared by melt mixing in a twin screw extruder followed by injection molding. The effect of clay chemistry and compatibilizer on the properties of the nanocomposites has been studied. Sodium montmorillonite has been organically modified using quaternary and alkyl amine intercalants. A comparative account with commercial quaternary ammonium modified clays i.e Cloisite 20A, Cloisite 15A and Cloisite 30B has been presented. Storage modulus of PP matrix also increased in the nanocomposites, indicating an increase in the stiffness of the matrix polymer with the addition of organically modified nanoclays. The morphology of the nanocomposites has been examined using wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). Morphological findings revealed efficient dispersion of organically modified nanoclays within the PP matrix. MAPP compatibilized PP/Cloisite 15A nanocomposites displayed finely dispersed exfoliated nanomorphology as compared with other systems.     

Toughening of bone cement using nanoparticle: The effect of solvent

Drawbacks of poly(methyl methacrylate) (PMMA)‐based bone cement as a grouting agent for in vivo fixation of orthopedic and dental implants such as considerable low mechanical strength have been improved using nanotechnology. Bone cement‐layered silicate nanocomposites have been prepared without any heat treatment in the presence of polar (dimethyl formamide, DMF) and nonpolar (benzene) solvents. Solvents have been removed completely from the bone cement after its preparation. Nanostructure is very much dependent on the solvent used for nanocomposite preparation, and benzene‐based nanocomposites are highly intercalated, whereas DMF‐based nanocomposites do not exhibit intercalation. Thermal stability of bone cement has improved in the presence of nanoclays. The relative enhanced interaction in case of benzene‐based nanocomposites has been shown through FTIR and UV–vis studies. The significant improvement in modulus and toughness of bone cement has been demonstrated in the presence of minimum amount of nanoclay for benzene‐based nanocomposites, whereas no change in modulus and reduced toughness have been observed for DMF‐based nanocomposites. The decrease of contact angle has been witnessed with increasing nanoclay concentration indicating better hydrophilic materials suitable for biomedical applications for greater cell growth. The reason for varying property enhancement in different solvents has been discussed considering the polarity effect and interactions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical,Thermal and Viscoelastic Behavior of Nylon 6/Clay Nanocomposites with Cotreated Montmorillonites

Nylon 6 nanocomposites were prepared using melt intercalation technique. Sodium montmorillonite (Na-MMT) was modified with octadecyl ammonium salt to evaluate the effect of clay modification on the performance of the nanocomposites. A comparative account with the nanocomposites prepared, using commercial clay cloisite 30B has been presented. X-ray diffraction (XRD) studies indicated an increase in the basal spacing of organically modified clays. Further, X-ray diffractograms of the nanocomposites displayed the absence of basal reflections suggesting the formation of an exfoliated structure. Transmission electron microscopy (TEM) investigations also confirmed exfoliation of clay galleries in the nanocomposites. Differential scanning calorimetry (DSC) measurements revealed both γ and α transitions in the matrix polymer as well as the nanocomposites. The crystallization temperature (T_c) exhibited a marginal increase in the C30B/Nylon 6 nanocomposites. Thermal stability of virgin Nylon 6 and the nanocomposites has been investigated using thermogravimetric analysis. Mechanical test revealed an increase in the tensile and flexural properties of Nylon 6 with the incorporation of nanoclays. Storage and loss modulus of virgin matrix increased with the incorporation of nanoclays. C30B/Nylon 6 nanocomposites exhibited optimum performance at 5% clay loading. Further, water absorption studies also confirmed comparatively lesser tendency of water uptake in these nanocomposites.     

Effect of different modified nanoclays on the kinetics of preparation and properties of polymer-based nanocomposites

Polymer-clay nanocomposites have been prepared by free radical and RAFT polymerizations. To investigate the effects of nanoclay content and its modification system on the kinetics of polymerization, two different commercial grades of clay including Na-MMT and Cloisite 30B have been used and a method has been developed for further modification of Na-MMT with two commercial modifiers containing either a long organic chain or a vinyl group. Also, kinetics of free radical and RAFT polymerizations of both styrene and methyl methacrylate in the presence of these nanoclays was studied. Morphology of the nanocomposites has been studied by XRD and the results have been assessed with TEM observations. Exfoliated structure was obtained for the nanocomposites with 1?wt.% of vinyl-containing clays. Thermogravimetric behavior of the nanocomposites has been studied by TGA. Incorporation of clays has resulted in an evident increase in thermal stability of both polymers.     

New polylactide/layered silicate nanocomposites. 5. Designing of materials with desired properties

Understanding the structure/property relationship in polymer/layered silicate nanocomposites is of great importance in designing materials with desired properties. In order to understand these relations, a series of polylactide (PLA)/organically modified layered silicate (OMLS) nanocomposites have been prepared using a simple melt extrusion technique. Four different types of OMLS have been used for the preparation of nanocomposites, three were modified with functionalized ammonium salts while fourth one was a phosphonium salt modified OMLS. The structure of the nanocomposites in the nanometer scale was characterized by using wide-angle X-ray diffraction and transmission electron microscopic observations. Using four different types of layered silicates modified with four different types of surfactants, the effect of OMLS in nanocomposites was investigated by focusing on four major aspects: structural analysis, thermal properties and spherulite morphology, materials properties, and biodegradability. Finally, we draw conclusions about the structure/property relationship in the case of PLA/OMLS nanocomposites.     

Si3N4／SiC纳米复相陶瓷研究进展

本文综述了Ｓｉ３Ｎ４／ＳｉＣ纳米复相陶瓷的研究进展,较详细地介绍了纳米粉体的制备工艺及热处理研究、复相陶瓷的制备工艺、力学性能、微观结构及增韧强化机理。     

Mechanical enhancement of zirconia reinforced polyimine nanocomposites

Polymeric nanocomposites have demonstrated superior performance in recent decades, combining the advantages of polymer and nanoparticle fillers. However, nanocomposites of polyimine, a neoteric thermoset material, have been rarely investigated. Herein, a series of polyimine nanocomposites reinforced by zirconia (ZrO₂) have been fabricated by heat‐pressing under mild conditions. The resultant polyimine nanocomposites show significant enhancements on multiple mechanical properties including tensile strength, toughness, bending strength, and impact strength, whereas the optimal amount of ZrO₂ particles for the best performance of a specific property varies. Interestingly, the tensile strength and toughness of the polyimine nanocomposites can be simultaneously increased by 40% and 85%, indicating that the nanocomposites exhibit excellent integration of tensile strength and toughness analogous to natural materials. Hence, a facile and cost‐effective approach to enhance mechanical properties of polyimine has been realized for more applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45183.     

Synthesis of Novel (Polymer Blend-Ceramics) Nanocomposites: Structural,Optical and Electrical Properties for Humidity Sensors

Fabrication of novel nanocomposites films of (PVA–CMC) blend and (PVA–CMC) blend doped by niobium carbide nanoparticles has been investigated. The structural, optical and electrical properties of (PVA–CMC–NbC) nanocomposites for humidity sensors have been studied. The (PVA–CMC–NbC) nanocomposites were prepared with different concentrations of (polyvinyl alcohol and carboxyl methyl cellulose) and Niobium carbide nanoparticles. The experimental results of optical properties for (PVA–CMC–NbC) nanocomposites showed that the absorbance, absorption coefficient, extinction coefficient, refractive index, real and imaginary dielectric constants and optical conductivity of (PVA–CMC) blend increase with increase in Niobium carbide nanoparticles concentrations. The transmittance and energy band gap decrease with increase in Niobium carbide nanoparticles concentrations. The DC electrical properties of (PVA–CMC–NbC) nanocomposites showed that the electrical conductivity of the blend increases with increase in NbC nanoparticles concentrations. The experimental results of novel (PVA–CMC–NbC) nanocomposites applications showed that the (PVA–CMC–NbC) nanocomposites have high sensitivity for relative humidity.     

Ethylene vinyl acetate/ethylene propylene diene terpolymer‐blend‐layered double hydroxide nanocomposites

Ethylene vinyl acetate (EVA‐45)/ethylene propylene diene terpolymer (EPDM) blend‐layered double hydroxide (LDH) nanocomposites have been prepared by solution blending of 1:1 weight ratio of EVA and EPDM with varying amounts of organo LDH (DS‐LDH). X‐ray diffraction and transmission electron microscopy analysis suggest the formation of partially exfoliated EVA/EPDM/DS‐LDH nanocomposites. Measurement of mechanical properties of the nanocomposites (3 wt% DS‐LDH content) show that the improvement in tensile strength and elongation at break are 35 and 12% higher than neat EVA/EPDM blends. Dynamic mechanical thermal analysis also shows that the storage modulus of the nanocomposites at glass transition temperature is higher compared to the pure blend. Such improvements in mechanical properties have been correlated in terms of fracture behavior of the nanocomposites using scanning electron microscopy analysis. Thermal stability of the prepared nanocomposites is substantially higher compared to neat EVA/EPDM blend, confirming the formation of high‐performance polymer nanocomposites. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers