首页 | 官方网站   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.
Development of cellulose nanofibrils (CNFs) reinforced polypropylene (PP) nanocomposites using melt compounding processes has received considerable attention. The main challenges are to obtain well‐dispersed CNFs in the polymer matrix and to establish compatible linkages between the CNFs and PP. Manufacturing of CNF reinforced PP nanocomposites was conducted using a twin‐screw co‐rotating extruder with the masterbatch concept. Modifications of CNFs using maleic anhydride polypropylene were performed. The best mechanical properties of the nanocomposites are 1.94 GPa (tensile modulus), 32.8 MPa (tensile strength), 1.63 GPa (flexural modulus), 50.1 MPa (flexural strength), and 3.8 kJ m−2 (impact strength), which represents about 36, 11, 21, 7, and 23% improvement, respectively, compared to those of pure PP (1.43 GPa, 29.5 MPa, 1.35 GPa, 46.9 MPa, and 3.1 kJ m−2). Fracture morphology examination indicated good dispersion of CNFs in the PP matrix was achieved through this specific manufacturing process. MAPP treatments enhanced the interfacial adhesion between the CNFs and PP. POLYM. COMPOS., 37:782–793, 2016. © 2014 Society of Plastics Engineers  相似文献   

2.
In this work, phase separation in carbon nanofiber (CNF) composites with a blend of ultrahigh molecular weight polyethylene (UHMWPE)/high‐density polyethylene (HDPE) was revealed, and its effects on tribological properties were investigated. Results from morphological analysis by optical and scanning electron microscopy indicated two distinct microstructures: a dispersed UHMWPE phase and a continuous microstructure containing HDPE and CNFs. The addition of CNFs into the UHMWPE/HDPE blend induced a decreased steady‐state torque indicative of a decreased dissolution and improved processability. Because CNFs predominantly resided into the HDPE phase, neat HDPE, a HDPE/CNF composite, and neat UHMWPE samples were also prepared for comparison. Wear results, determined by a pin‐on‐disk apparatus, showed that both initial run‐in and steady‐state wear rates of the UHMWPE/HDPE/CNF nanocomposites were reduced with an increasing concentration of CNFs. The wear resistance of the UHMWPE/HDPE blend was more strongly influenced than neat HDPE by the addition of CNFs, which may have been affected by a reduced dissolution and improved interfacial interaction between the two phases. Results from this study suggested that HDPE may not be appropriate for processing UHMWPE composites, as CNFs reside in the HDPE phase, and HDPE diminishes the wear resistance of the material. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers  相似文献   

3.
Poly(lactic acid) (PLA) nanocomposites were prepared by melt mixing technique in a Haake batch mixer. The clay dispersion within the PLA matrix during melt mixing was well explained through the morphological characterization. Morphological characterizations were studied by X‐ray diffraction and transmission electron microscopy. The exfoliation/intercalation of the clay particles within the polymer matrix during melt mixing depends on the mixing torque generated during the preparation of nanocomposites. The significance of processing temperature and the mixing time in melt mixing were studied for PLA/C93A and PLA/C30B nanocomposites. The structure and properties of the nanocomposites were also characterized by differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and mechanical properties by standard tensile testing. The incorporation of nanoclays into the PLA matrix enhanced the mechanical properties and thermal stability of the PLA nanocomposites. This may be due to the reinforcing effect of nanoclays within the polymer matrix. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers  相似文献   

4.
Poly(ethylene terephthalate) (PET)/Cloisite 30B (C30B) nanocomposites containing different concentrations of the organoclay were prepared using two different twin‐screw extrusion processes: conventional melt mixing and water‐assisted melt mixing. The reduction of the molecular weight of the PET matrix, caused by hydrolysis during the water‐assisted extrusion, was compensated by subsequent solid‐state polymerization (SSP). X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses showed intercalated/exfoliated morphology in all PET/C30B nanocomposites, with a higher degree of intercalation and delamination for the water‐assisted process. Rheological, thermal, mechanical, and gas barrier properties of the PET nanocomposites were also studied. Enhanced mechanical and barrier properties were obtained in PET‐C30B nanocomposites compared to the neat PET. The nanocomposites exhibited higher tensile modulus and lower oxygen permeability after SSP. The elongation at break was significantly higher for SSP nanocomposites than for nanocomposites processed by conventional melt mixing. POLYM. ENG. SCI., 54:1879–1892, 2014. © 2013 Society of Plastics Engineers  相似文献   

5.
A novel aromatic amine organo‐modifier synthesized in our previous work was used to treat montmorillonite (MMT) and the organo‐modified MMT was used to prepare poly(etherimide) (PEI)/MMT nanocomposites by a melt intercalation method. MMT treated by this amine exhibited large layer‐to‐layer spacing and a high ion‐exchange ratio (>95%). The nanocomposites were characterized with X‐ray diffraction (XRD), transmission electron microscopy (TEM), dynamic mechanical analysis, a universal tester, thermogravimetric analysis, and by differential scanning calorimetry. The results of XRD and TEM showed that the nanocomposites formed exfoliated structures even when the MMT content was 10 wt %. When the MMT content was below 3 wt %, the PEI/MMT nanocomposites were strengthened and toughened at the same time. The nanocomposites also showed marked decreases in coefficient of thermal expansion and solvent uptake. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1857–1863, 2003  相似文献   

6.
The objective of the study is to investigate the effect of inclusion of nanotalc on the strength properties of polyamide 6 (PA6)‐based binary and ternary nanocomposites. Binary nanocomposites were prepared by melt compounding of PA6 with varying content of nanotalc (1, 2, and 4 wt%). Ternary nanocomposites were prepared by melt compounding of compatibilized blend of PA 6 and ethylene‐co‐butyl acrylate (EBA elastomer) with varying content of nanotalc (1, 2, and 4 wt%). Both the binary and ternary nanocomposites registered a very high improvement in the strength/stiffness‐related properties at lower filler loading of 1 wt%. Phase morphology of the composites studied by SEM, TEM, and XRD revealed the formation of extended brane‐like structures and delaminated talc layers in the binary nanocomposites. The modulus predicted by Halpin‐Tsai and Mooney equation suggests that the composites retained a very good aspect ratio after melt mixing. Orientation effects of nanotalc enhanced the melt flow behavior in the composites. POLYM. ENG. SCI., 50:1978–1993, 2010. © 2010 Society of Plastics Engineers  相似文献   

7.
Carbon nanofiber (CNF) based polysulfone (PSU) nanocomposites have been developed successfully by a innovative solution mixing technique to explore the effect of state of dispersion and wt% loading of CNFs on different properties of PSU. In order to enhance the interfacial adhesion between CNFs and PSU, CNFs were functionalized by air oxidation. Thermal properties were characterized by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and it was seen that thermal stability of PSU was increased with increase in CNFs loading. The state of dispersion of CNFs throughout the PSU matrix and PSU–CNFs interaction were confirmed using field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) study. The electrical properties of nanocomposites were studied from direct current (DC) and alternating current (AC) resistivity measurement. DC resistivity registered a very low percolation threshold in‐between 0.5–1 wt% of CNFs loading. DC resistivity of PSU was decreased by nine orders of magnitude with the addition of 1 wt% CNFs loading. Dielectric constant and dissipation factor of nanocomposites were significantly increased with increase in CNFs content in nanocomposites. The enhancement in these properties suggests a great potential application of the resulting nanocomposites as multifunctional materials in various electronics industries. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers  相似文献   

8.
Natural fiber‐reinforced nanocomposites based on polypropylene/nanoclay/banana fibers were fabricated by melt mixing in a twin‐screw extruder followed by compression molding in this current study. Maleic anhydride polypropylene copolymer (MA‐g‐PP) was used as a compatibilizer to increase the compatibility between the PP matrix, clay, and banana fiber to enhance exfoliation of organoclay and dispersion of fibers into the polymer matrix. Variation in mechanical, thermal, and physico‐mechanical properties with the addition of banana fiber into the PP nanocomposites was investigated. It was observed that 3 wt% of nanoclay and 5 wt% of MA‐g‐PP within PP matrix resulted in an increase in tensile and flexural strength by 41.3% and 45.6% as compared with virgin PP. Further, incorporation of 30 wt% banana fiber in PP nanocomposites system increases the tensile and flexural strength to the tune of 27.1% and 15.8%, respectively. The morphology of fiber reinforced PP nanocomposites has been examined by using scanning electron microscopy and transmission electron microscopy. Significant enhancement in the thermal stability of nanocomposites was also observed due to the presence of nanoclay under thermogravimetric analysis. Dynamic mechanical analysis tests revealed an increase in storage modulus (E′) and damping factor (tan δ), conforming the strong interaction between nanoclay/banana fiberand MA‐g‐PP in the fiber‐reinforced nanocomposites systems. POLYM. COMPOS., © 2011 Society of Plastics Engineers.  相似文献   

9.
Blends of organically modified montmorillonite (OMMT) with poly(ethylene terephtalate) (PET) waste and poly(methyl methacrylate) (PMMA) were prepared by melt mixing. The morphology of PET/PMMA nanocomposites with different OMMT contents was characterized by transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The nonisothermal crystallization temperatures of nanocomposites were also examined by DSC. TEM observations and XRD patterns revealed that silicate layers were intercalated and well dispersed in the blend. Nanocomposites displayed better mechanical properties when compared with the unfilled blend. DMA analyses also showed efficient mixing of the two immiscible polymers and changes in glass transition temperature with the presence of OMMT. DSC analysis showed an enhancement in crystallization rate of nanocomposites and a decrease in cristallinity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

10.
Nylon 6 (PA‐6) organoclay nanocomposites were prepared by melt processing using three different twin screw extruders (TSEs). The effect of mixing conditions, feed port location, residence time, and number of extrusion passes on the morphology and mechanical properties of the nanocomposites were examined. Wide‐angle X‐ray scattering, transmission electron microscopy (TEM), and mechanical property data are reported. Particle analyses were performed on the TEM images to quantitatively characterize the extent of exfoliation. The amount of shear and the mixing conditions created by TSEs have a significant effect on the morphology and properties of PA‐6 nanocomposites. Morphology and mechanical property results show that (1) melting the polymer before coming into contact with the organoclay followed by a low level of shear and (2) maintaining a medium level of shear throughout the extruder with a longer residence time lead to extremely high platelet dispersion and matrix reinforcement for PA‐6 nanocomposites. Nanocomposites formed in a DSM microcompounder showed similar morphologies and modulus trends as those obtained with conventional TSEs; thus, this microcompounder is a good alternative for nanocomposite research especially when only small amounts of material are available. POLYM. ENG. SCI., 47:1847–1864, 2007. © 2007 Society of Plastics Engineers  相似文献   

11.
Preparation of thermally stable recycled PET‐organoclay nanocomposites with improved processing and mechanical properties is a challenging task from the environmental as well as industrial and commercial point of view. In this work, both modification of sodium‐type montmorillonite with 1,2‐dimethyl‐3‐octadecyl‐1H‐imidazol‐3‐ium chloride and additional treatment with [3‐(glycidyloxy)propyl]trimethoxysilane was performed. Thermal stability of the organoclays and nanocomposites prepared by melt compounding was tested by thermogravimetric analysis, differential scanning calorimetry, and melt rheology. In comparison with the organoclays modified with quaternary ammonium compounds, the prepared clays showed substantial suppression of matrix degradation during melt mixing. The increase in interlayer distance of silicate platelets and homogeneity of dispersions in the recycled and virgin PET matrices have been evaluated by transmission electron microscopy and wide‐angle X‐ray scattering. The higher degree of delamination in the nanocomposites filled with imidazole organoclays was in a good agreement with improved rheological characteristics and led to significant enhancement in mechanical properties and thermal stability. A difference in structure (besides the level of delamination and homogeneity of silicate platelets) of recycled versus virgin PET nanocomposites was detected by X‐ray diffraction patterns. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

12.
Nanocomposites based on thermoplastic polyurethane (TPU) and organically modified montmorillonite (OMMT) were prepared by melt blending. Organically modified nanoclay was added to the TPU matrix in order to study the influence of the organoclay on nanophase morphology and materials properties. The interaction between TPU matrix and nanofiller was studied by infrared spectroscopy. Morphological characterization of the nanocomposites was carried out using X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy techniques. The results showed that melt mixing is an effective process for dispersing OMMT throughout the TPU matrix. Nanocomposites exhibit higher mechanical and thermal properties than pristine TPU. All these properties showed an increasing trend with the increase in OMMT content. Thermogravimetric analysis revealed that incorporation of organoclay enhances the thermal stability of nanocomposites significantly. Differential scanning calorimetry was used to measure the melting point and the glass transition temperature (Tg) of soft segments, which was found to shift toward higher temperature with the inclusion of organoclays. From dynamic mechanical thermal analysis, it is seen that addition of OMMT strongly influenced the storage and loss modulus of the TPU matrix. Dynamic viscoelastic properties of the nanocomposites were explored using rubber process analyzer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

13.
Poly(lactic acid) (PLA)/SiO2 nanocomposites were prepared via melt mixing with a Haake mixing method. To improve the dispersion of nanoparticles and endow compatibility between the polymer matrix and nanosilica, SiO2 was surface‐modified with oleic acid (OA). The interfacial adhesion of the PLA nanocomposites was characterized by field‐emission scanning electron microscopy. The storage modulus and glass‐transition temperature values of the prepared nanocomposites were measured by dynamic mechanical thermal analysis. The linear and nonlinear dynamic rheological properties of the PLA nanocomposites were measured with a parallel‐plate rheometer. The effects of the filling content on the dispersability of the OA–SiO2 nanoparticles in the PLA matrix, the interface adhesion, the thermomechanical properties, the rheological properties, and the mechanical properties were investigated. Moreover, the proper representation of the oscillatory viscometry results provided an alternative sensitive method to detect whether aggregation formed in the polymeric nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

14.
Polyethylene-octene elastomer/organoclay nanocomposites were prepared by a melt blending process. It was found that the addition of a small amount of glycidyl methacrylate and a peroxide during the melt mixing induced facile intercalation of the polymer chains into the organoclay and dispersion of the clay particles on the nanometer scale, which was confirmed by X-ray diffraction and transmission electron microscopy. Enhanced mechanical properties of the nanocomposites were observed from tensile, dynamic mechanical, and tear testing. Oscillatory shear-controlled rheology in the molten state of the nanocomposites revealed a pseudo solid-like behavior as well as an enhanced shear thinning behavior.  相似文献   

15.
Poly(ether ether ketone), PEEK, is a widely used engineering plastic that is especially suitable for high temperature applications. Compounding of PEEK with carbon nanofibers, CNF, has the potential of enhancing its mechanical and thermal properties further, even at relatively low CNF concentrations. However, such enhancements can be compromised by myriad factors, some of which are elucidated in this study. Considering that the dispersion of the CNF into any high molecular weight polymer is a challenge, two different processing methods, i.e., melt and solution processing were used to prepare PEEK nanocomposites with low aspect ratio carbon nanofibers. The linear viscoelastic material functions of PEEK nanocomposites in the solid and molten states were characterized as indirect indicators of the dispersion state of the nanofibers and suggested that the dispersion of nanofibers into PEEK becomes difficult at increasing CNF concentrations for both solution and melt processing methods. Furthermore, the time-dependence of the linear viscoelastic material functions of the PEEK/CNF nanocomposites at 360-400 °C indicated that PEEK undergoes thermo-oxidative cross-linking under typical melt processing conditions, thus preventing better dispersion by progressive increases of the mixing time and specific energy input during melt processing. The crystallization behavior of PEEK is also affected by the presence of CNF and degree of cross-linking, with the rate of crystallization decreasing with increasing degree of cross-linking and upon the incorporation of CNFs both for the solution and melt processed PEEK nanocomposites.  相似文献   

16.
Polystyrene (PS)/organomontmorillonite nanocomposites were prepared by melt processing with a twin‐screw extruder. Sodium montmorillonite was organically modified with stearyl trimethyl ammonium chloride to evaluate the effect of clay modification on the performance of the nanocomposites. A comparative account of nanocomposites prepared with the commercial clay Cloisite 20A (C20A) is presented. X‐ray diffraction studies indicated that the clay layers were completely dispersed, and a delaminated structure was formed in the case of C20A/PS and organomontmorillonite/PS nanocomposites. The dispersion characteristics of the clays within the matrix polymer were further investigated through transmission electron microscopy analysis. Mechanical tests revealed increases in the tensile, flexural, and impact strengths of 83, 55, and 74%, respectively, for C20A/PS nanocomposites at a 5% clay loading. The viscoelastic response of the nanocomposites, studied with dynamic mechanical analysis, also showed a substantial increase in the storage modulus of the nanocomposites with the incorporation of organically modified nanoclays. Furthermore, the melt‐state rheology of the organically modified nanocomposites displayed three distinct regions—glassy, plateau, and terminal—from the high‐frequency region to the low‐frequency region, with a considerable increase in the storage modulus in the glassy and terminal regions. Differential scanning calorimetry and thermogravimetric analysis were also used to evaluate the effect of the addition of nanoclays on the glass‐transition temperature and thermal stability of the PS matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

17.
This study provides information on the mechanical behavior of epoxy‐poly(methyl methacrylate) (PMMA)‐clay ternary composites, which have been prepared using the phase separation phenomenon of PMMA and the introduction of organophilic‐modified montmorillonites (MMTs), the continuous matrix being the epoxy network. Two dispersion processing methods are used: a melt processing without any solvent and an ultrasonic technique with solvent and a high‐speed stirrer. TEM analysis shows that phase separation between PMMA and the epoxy network was obtained in the shape of spherical nodules in the presence of the clay in both process methods used. Nanoclay particles were finely dispersed inside thermosetting matrix predominantly delaminated when ultrasonic blending was used; whereas micrometer‐sized aggregates were formed when melt blending was used. The mechanical behavior of the ternary nanocomposites was characterized using three‐point bending test, dynamic mechanical analysis (DMA), and linear elastic fracture mechanics. The corresponding fracture surfaces were examined by scanning electron microscopy to identify the relevant fracture mechanisms involved. It was evidenced that the better dispersion does not give the highest toughness because ternary nanocomposites obtained by melt blending present the highest fracture parameters (KIc). Some remaining disordered clay tactoids seem necessary to promote some specific toughening mechanisms. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

18.
Novel carbon nanofiber (CNF) ‐filled bismalemide composites were fabricated by a thermokinetic mixing method. The thermal and mechanical properties of composites containing 1 wt % and 2 wt % CNFs were investigated. Thermogravimetric analysis demonstrated that minimal improvement in thermal stability of the nanocomposites was obtained by the addition of CNFs. Dynamic mechanical analysis showed an increase in storage modulus (E′) and glass transition temperature (Tg) upon incorporation of nanofibers. Limiting oxygen index (LOI) has also been found to increase with incorporation of CNFs. Morphological studies of fractured surfaces of the composites has been carried out by scanning electron microscopy to determine the effect of fiber content and dispersion on the failure mechanism. In general, good dispersion was observed, along with agglomeration at some points and some fiber matrix interfacial debonding. A decrease in mechanical strength has been observed and debonding was found as the main failure mechanism. Further research outlook is also presented. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

19.
Nanocomposites of organic nano‐montmorillonite (nano‐OMMT)‐filled immiscible polyamide 6 (PA6)/polystyrene (PS) blends were prepared by three different processing methods. Masterbatch M1 of OMMT/PA6 and masterbatch M2 of OMMT/PS were prepared as separate masterbatchs by melt mixing with PA6 or PS, and then either mixed together or each mixed individually with appropriate amounts of PS or PA6, respectively. The effects of nano‐OMMT content and processing method on the structure, phase morphology, and mechanical properties of the PA6/PS/OMMT nanocomposites were investigated by X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, and mechanical properties tests. The results showed that the nano‐OMMT by M1 and M2 masterbatches dispersed primarily as exfoliated platelets in the PA6 matrix in the final composites regardless of the method of preparation. A drastic decrease of dispersed PS phase size and a very homogeneous size distribution were observed with the addition of nano‐OMMT. The PA6/PS/OMMT nanocomposites prepared from the M2 displayed the smallest dispersed PS phase size and best distribution of OMMT. The improvement of the mechanical properties of the PA6/PS/OMMT nanocomposites was attributed to the enhanced compatibilization of the immiscible PA6/PS blends by using nano‐OMMT. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers  相似文献   

20.
Clay containing polypropylene (PP) nanocomposites were prepared by direct melt mixing in a twin screw extruder using different types of organo‐modified montmorillonite (Cloisite 15 and Cloisite 20) and two masterbatch products, one based on pre‐exfoliated clays (Nanofil SE 3000) and another one based on clay–polyolefin resin (Nanomax‐PP). Maleic anhydride‐grafted polypropylene (PP‐g‐MA) was used as a coupling agent to improve the dispersability of organo‐modified clays. The effect of clay type and clay–masterbatch product on the clay exfoliation and nanocomposite properties was investigated. The effect of PP‐g‐MA concentration was also considered. Composite morphologies were characterized by X‐ray diffraction (XRD), field emission gun scanning electron microscopy (FEG‐SEM), and transmission electron microscopy (TEM). The degree of dispersion of organo‐modified clay increased with the PP‐g‐MA content. The thermal and mechanical properties were not affected by organo‐modified clay type, although the masterbatch products did have a significant influence on thermal and mechanical properties of nanocomposites. Intercalation/exfoliation was not achieved in the Nanofil SE 3000 composite. This masterbatch product has intercalants, whose initial decomposition temperature is lower than the processing temperature (T ~ 180°C), indicating that their stability decreased during the process. The Nanomax‐PP composite showed higher thermal and flexural properties than pure PP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  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-23

京公网安备 11010802026262号