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 15 毫秒
1.
We present the first study and results on the preparation and characterization of montmorillonite clay filler based polymer blend nanocomposites of the miscible poly(phenylene oxide)/polystyrene blend. Intercalated nanocomposites, prepared by a melt‐processing method with 2–6 wt % commercially available organically modified sodium montmorillonite, have been characterized with wide‐angle X‐ray diffraction, transmission electron microscopy analysis, thermal analysis (thermogravimetric analysis and differential scanning calorimetry), and mechanical tensile tests. We show that nanocomposites can be successfully prepared in a batch mixer at temperatures much below the conditions conventionally used for this blend without organic degradation. Thermal stability is enhanced by nanoscale hybrid formation. The level of intercalation (change in the d‐spacing) does not change with the clay loading. Better dispersion of clay in the blend matrix has been observed at a low level of clay content. The nanocomposites show improved tensile modulus (by 31%) in comparison to the blend, whereas the tensile strength (stress at break) and elongation decrease in the presence of the filler with an increase in the clay loading. The Halpin–Tsai model is able to predict the modulus of the nanocomposites in very good agreement with the experimental data. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

2.
Poly(trimethylene terephthalate) (PTT)/polypropylene (PP) blend nanocomposites were prepared by melt mixing of PTT, PP, and organically modified clay. The phase morphologies of the PTT/PP nanocomposites and the distribution of the clay in the nanocomposites were investigated using scanning electron microscopy, transmission electron microscopy (TEM), and wide angle X‐ray diffraction. When PP is the dispersed phase, the domain size of the PP phase is decreased significantly with increasing the clay content from 0 to 5 wt %. In contrast, when PTT is the dispersed phase, the dimension of the PTT phase is a little larger in the presence of 2 wt % clay compared with the case of without clay. TEM observations indicate that the clay is mainly distributed at the phase interfaces along the phase borderlines. In addition, some intercalated clay tactoids (multilayer particles) are observed in the PTT matrix whereas no discernable clay particles can be found in the PP phase, indicating that the affinity of clay with PTT is higher than with PP. In the presence of 5 wt % PP‐graft‐maleic anhydride, the phase morphology is much finer, and most clay is exfoliated and distributed at the phase interfaces forming phase borderlines in polygonal shape. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

3.
The effect of cooling rate on crystallization and subsequent aging of high stereoregular poly(lactide) (PLA) blended with poly(ethylene glycol) (PEG) was studied by thermal analysis and by direct observation of the solid state structure with atomic force microscopy (AFM). Blending with PEG accelerated crystallization of PLA. When a PLA/PEG 70/30 (wt/wt) blend was slowly cooled from the melt, PLA crystallized first as large spherulites followed by crystallization of PEG. The extent of PLA crystallization depended on the cooling rate, however, for a given blend composition the PEG crystallinity was proportional to PLA crystallinity. The partially crystallized blend obtained with a cooling rate of 30 °C min−1 consisted of large spherulites dispersed in a homogeneous matrix. The blend was not stable at ambient temperature. With time, epitaxial crystallization of PEG on the edges of the spherulites depleted the surrounding region of PEG, which created a vitrified region surrounding the spherulites. Further from the spherulites, the homogeneous amorphous phase underwent phase separation with formation of a more rigid PLA-rich phase and a less-rigid PEG-rich phase. Decreasing the amount of PEG in the blend decreased the crystallization rate of PLA and increased the nucleation density. The amount of PLA crystallinity did not depend on blend composition, however, PEG crystallinity decreased to the extent that PEG did not crystallize in a PLA/PEG 90/10 (wt/wt) blend.  相似文献   

4.
Poly(lactic acid)/poly(ε‐caprolactone)/organically modified montmorillonite (PLA/PCL/OMMT) nanocomposites were melt‐processed in a twin‐screw extruder under high shear conditions. As a result of the processing conditions employed, the OMMT layers located in the less compatible PCL phase in all the ternary nanocomposites. The morphology of the PLA/PCL blend evolved from “sea‐island” to co‐continuous upon the addition of OMMT. Both the X‐ray diffraction (XRD) and viscoelastic characterization suggested similar OMMT dispersion in the reference PLA binary and in the PLA/PCL ternary nanocomposites, regardless of its location in the PLA and PCL phase, respectively. The reinforcing effect of the organoclay was also similar. The addition of OMMT to the PLA/PCL blend fully compensated the loss in stiffness and oxygen barrier performance produced by PCL in PLA; the nanocomposite with 3% OMMT showed the same modulus and permeability values as those of pure PLA. Moreover, the ductile behavior (elongation at break > 80%) of the PLA/PCL blend remained constant even in the nanocomposite containing 5% OMMT. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43815.  相似文献   

5.
This work presented the influence of thermoplastic poly(ether-ester) elastomer (TPEE) and bentonite (BTN) on improving the mechanical and thermal properties of poly(lactic acid) (PLA). PLA was initially melt mixed with TPEE at six different loadings (5–30 wt%) on a twin screw extruder and then injection molded. The mechanical tests revealed an increasing impact strength and elongation at break with increasing TPEE loading, but a diminishing Young's modulus and tensile strength with respect to pure PLA. The blend at 30 wt% TPEE provided the optimum improvement in toughness, exhibiting an increase in the impact strength and elongation at break by 3.21- and 10.62-fold over those of the pure PLA, respectively. Scanning electron microscopy analysis illustrated a ductile fractured surface of the blends with the small dispersed TPEE domains in PLA matrix, indicating their immiscibility. The 70/30 (wt/wt) PLA/TPEE blend was subsequently filled with three loadings of BTN (1, 3, and 5 parts by weight per hundred of blend resin [phr]), where the impact strength, Young's modulus, tensile strength and thermal stability of all the blends were improved, while the elongation at break was deteriorated. Among the three nanocomposites, that with 1 phr BTN formed exfoliated structure and so exhibited the highest impact strength, elongation at break, and tensile strength compared to the other intercalated nanocomposites. Moreover, the addition of BTN was found to increase the thermal stability of the neat PLA/TPEE blend due to the barrier properties and high thermal stability of BTN.  相似文献   

6.
The blends of high molecular weight poly(propylene carbonate) (PPC) and poly(butylene succinate) (PBS) were melt blended using triphenylmethane triisocyanate (TTI) as a reactive coupling agent. TTI also serves as a compatibilizer for the blends of PPC and PBS. The blend containing 0.36 wt % TTI showed that the optimal mechanical properties were, therefore, calendared into films with different degrees of orientation. The calendering condition, degree of orientation, morphologies, mechanical properties, crystallization, and thermal behaviors of the films were investigated using wide‐angle X‐ray diffraction, scanning electron microscopy, tensile testing, and differential scanning calorimetry (DSC) techniques. The result showed that the as‐made films exhibited obvious orientation in machine direction (MD). Both tensile strength in MD and the tear strength in transverse direction (TD) increased with increasing the degree of orientation. The orientation of the film also increased the crystallinity and improved the thermal properties of the PPC/PBS blend films. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

7.
Blends of poly(L ‐lactic acid) (PLA) and poly(butylene succinate) (PBS) were prepared with various compositions by a melt‐mixing method and the phase behavior, miscibility, and morphology were investigated using differential scanning calorimetry, wide‐angle X‐ray diffraction, small‐angle X‐ray scattering techniques, and polarized optical microscopy. The blend system exhibited a single glass transition over the entire composition range and its temperature decreased with an increasing weight fraction of the PBS component, but this depression was not significantly large. The DSC thermograms showed two distinct melting peaks over the entire composition range, indicating that these materials was classified as semicrystalline/semicrystalline blends. A depression of the equilibrium melting point of the PLA component was observed and the interaction parameter between PLA and PBS showed a negative value of ?0.15, which was derived using the Flory–Huggins equation. Small‐angle X‐ray scattering revealed that, in the blend system, the PBS component was expelled out of the interlamellar regions of PLA, which led to a significant decrease of a long‐period, amorphous layer thickness of PLA. For more than a 40% PBS content, significant crystallization‐induced phase separation was observed by polarized optical microscopy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 647–655, 2002  相似文献   

8.
This study examines the influence of three different minerals, that is, clay, calcium carbonate, and quartz on the physical, thermal, and mechanical properties of poly(lactic acid) (PLA)/poly(methyl methacrylate) blend. Rheological behavior and phase structure were initially studied by small-amplitude oscillatory shear rheology. Clay- and quartz-filled materials presented an increase in viscosity at low frequency associated with the presence of a yield stress. However, this behavior was not observed for calcium carbonate filled materials due to a matrix degradation effect. To elucidate this aspect, thermal stability and thermal properties were examined by thermogravimetric analysis and differential scanning calorimetry, showing that calcium carbonate promotes degradation of the PLA phase. No nucleating effect was observed in the presence of the minerals. Dynamical mechanical analysis and mechanical characterization revealed an increase of the overall softening temperature and, a reinforcing effect for clay- and quartz-based composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46927.  相似文献   

9.
A series of blends based on poly(lactic acid) (PLA) and poly[(butylene succinate)‐co‐adipate] (PBSA) as well as their nanocomposites with nanoclay (PLA/PBSA/Clay ternary nanocomposites) were prepared using the twin‐screw extruder. The blends were prepared for PBSA contents ranging from 25 to 75 wt % and their corresponding nanocomposites were prepared at a single‐clay concentration. The morphology and structure of the blends and the nanocomposites were examined using field emission scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction. Rheological properties (dynamic oscillatory shear measurements and elongational viscosities) of the blends, nanocomposites, and pure components were studied in detail. The strain hardening intensity of different blends and nanocomposites was compared with the behavior of the pure components. Strong strain hardening behavior was observed for blends composed of 50 wt % and higher PBSA content. However, the effect of PBSA content on the elongational viscosity was less pronounced in PLA/PBSA/Clay ternary nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

10.
Nanocomposites based on blends of poly(butylene succinate) (PBS) and thermoplastic cassava starch (TPS) were prepared using a two‐roll mill and compression molding, respectively. Two different types of clay, namely sodium montmorillonite (CloisiteNa) and the organo‐modified MMT (Cloisite30B) were used. The morphological and mechanical properties of the nanocomposite materials were determined by using XRD technique and a tensile test, respectively. Thermal properties of the composite were also examined by dynamic mechanical thermal analysis and thermal gravimetric techniques. Barrier properties of the nanocomposites were determined using oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) tests. From the results, it was found that by adding 5 pph of the clay, the tensile modulus and the thermal properties of the blend containing high TPS (75 wt %) changed significantly. The effects were also dependent on the type of clay used. The use of Cloisite30B led to a nanocomposite with a higher tensile modulus value, whereas the use of CloisiteNa slightly enhanced the thermal stability of the material. OTR and WVTR values of the blend composites containing high PBS ratio (75 wt %) also decreased when compared to those of the neat PBS/TPS blend. XRD patterns of the nanocomposites suggested some intercalation and exfoliation of the clays in the polymer matrix. The above effects are discussed in the light of different interaction between clays and the polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1114‐1123, 2013  相似文献   

11.
In this study, melt intercalation method is applied to prepare poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG)‐plasticized PLA nanocomposite films including 0, 3, and 5% organoclay (Cloisite 30B) using a laboratory scale compounder, which is connected to a microcast film device. To evaluate the nanomorphology and the dispersion state of the clays, X‐ray diffraction (XRD) and transmission electron microscopy (TEM) are conducted. Tensile tests are performed to characterize the mechanical behavior of the films. Biodegradation rate is determined by degradation tests in composting medium. Differential scanning calorimeter (DSC) is applied to observe the thermal behavior of the films. XRD and TEM show that the exfoliation predominantly occurrs in plasticized PLA nanocomposites, whereas unexfoliated agglomerates together with exfoliated clays are observed in the nonplasticized PLA. Tensile tests indicate that the addition of 3% clay to the neat‐PLA does not affect the strength; however, it enhances the modulus of the nanocomposites in comparison to neat‐PLA. Incorporation of 3% clay to the plasticized PLA improves the modulus with respect to PLA/PEG; on the other hand, the strain at break value is lowered ~ 40%. The increase in the rate of biodegradation in composting medium is found as in the order of PLA > PLA/PEG > 3% Clay/PLA/PEG > 5% Clay/PLA/PEG > 3% Clay/PLA. DSC analysis shows that the addition of 3% clay to the neat PLA results in an increase in Tg. The addition of 20% PEG as a plasticizer to the neat‐PLA decreases Tg about 30°C, however incorporation of clays increases Tg by 4°C for the plasticized PLA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

12.
In this work, an innovative approach to overcome the issue of the poor thermo‐oxidative stability of polymer/clay nanocomposites is proposed. Specifically, biodegradable poly(lactic acid) (PLA)‐based nanocomposites, containing organo‐modified clay with in‐built antioxidant activity, were prepared. Through a two‐step chemical protocol, a hindered phenol antioxidant was chemically linked to the ammonium quaternary salt which was then intercalated between the clay platelets [(AO)OM‐Mt]. The nanocomposites were characterized and their thermo‐oxidative stability during melt processing and under long‐term thermal test conditions was investigated. PLA nanocomposites containing the (AO)OM‐Mt showed higher oxidative stability, along with better clay dispersion, compared to PLA‐nanocomposites containing commercial clay and a free hindered phenol antioxidant. Obtained results can be explained considering that (AO)OM‐Mt may act locally, at the interface, between the silicate layers and the polymer macromolecules, thus contributing to the observed improved stability of the polymer both during processing and under long‐term thermal‐oxidative conditions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44974.  相似文献   

13.
Poly(styrene‐co‐methacrylic acid) containing 29 mol % of methacrylic acid (SMA‐29) and poly(isobutyl methacrylate‐co‐4‐vinylpyridine) containing 20 mol % of 4‐vinylpyridine (IBM4VP‐20) were synthesized, characterized, and used to elaborate binary and ternary nanocomposites of different ratios with a 3% by weight hexadecylammonium‐modified bentonite from Maghnia (Algeria) by casting method from tetrahydrofuran (THF) solutions. The morphology and the thermal behavior of these binary and ternary elaborated nanocomposites were investigated by X‐ray diffraction, scanning electron microscopy, FTIR spectroscopy, differential scanning calorimetry, and thermogravimetry. Polymer nanocomposites and nanoblends of different morphologies were obtained. The effect of the organoclay and its dispersion within the blend matrix on the phase behavior of the miscible SMA29/IBM4VP20 blends is discussed. The obtained results showed that increasing the amount of SMA29 in the IBM4VP20/SMA29 blend leads to near exfoliated nanostructure with significantly improved thermal stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

14.
The objectives of this study are to investigate the effect of silica nanoparticles on the morphology and rheological behavior of immiscible linear low‐density polyethylene/poly(lactic acid) (LLDPE/PLA) blends. Melt blending method is applied to prepare the blends and their nanocomposites. Scanning electron microscope and parallel plate rheometer were used to investigate morphology and rheological behavior of the blend nanocomposites. Scanning electron microscope results demonstrated a significant change in morphology behavior by incorporation of silica nanoparticles. A significant reduction in the PLA droplet for LLDPE/PLA (75/25) with 8 wt % silica was observed. The rheological studies illustrated that for all samples storage modulus and complex viscosity of blend nanocomposites are higher than neat blends. Finally, melt rigidity of blend nanocomposites was estimated by measurement of rheological properties using a rotational rheometer through small amplitude oscillatory shear experiments. As a result, through the shear data, a high value quantity as a criteria for melt rigidity is obtained for the LLDPE/PLA (75/25) with 8 wt % silica in comparing to the other samples. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45526.  相似文献   

15.
Multiwall carbon nanotube reinforced poly (phenylene sulfide) (PPS) nanocomposites were successfully fabricated through melt compounding. Structural, electrical, thermal, rheological, and mechanical properties of the nanocomposites were systematically studied as a function of carbon nanotube (CNT) fraction. Electrical conductivity of the polymer was dramatically enhanced at low loading level of the nanotubes; the electrical percolation threshold lay between 1 and 2 wt % of the CNTs. Rheological properties of the PPS nanocomposites also showed a sudden change with the CNT fraction; the percolation threshold was in the range of 0–0.5 wt % of CNTs. The difference in electrical and rheological percolation threshold was mainly due to the different requirements needed in the carbon nanotube network in different stages. The crystallization and melting behavior of CNT‐filled PPS nanocomposites were studied with differential scanning calorimetry; no new crystalline form of PPS was observed in the nanocomposites, but the crystallization rate was reduced. The thermal and mechanical properties of the nanocomposites were also investigated, and both of them showed significant increase with CNT fraction. For 5 wt % of CNT‐filled PPS composite, the onset of degradation temperature increased by about 13.5°C, the modulus increased by about 33%, and tensile strength increased by about 172%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

16.
Poly(lactic acid) (PLA) is a well known biodegradable thermoplastic with excellent mechanical properties that is a product from renewable resources. However, the brittleness of PLA limits its general applications. Using epoxidized soybean oil (ESO) as a novel plasticizer of poly(lactic acid), the composite blend with the twin‐screw plastic extruder at five concentrations, 3, 6, 9, 12, and 15 wt %, respectively. Compared with pure PLA, all sets of blends show certain improvement of toughness to different extents. The concentration with 9 wt % ESO increases the elongation at break about 63%. The melt flow rates of these blends with respect to different ESO ratio have been examined using a melt flow indexer. Rheological behaviors about shear viscosity and melt strength analysis are discussed based on capillary rheology measurements. The tensile strength and melt strength of the blends with 6 wt % ESO simultaneity reach the maximums; whereas the elongation at break of the blends is the second highest level. ESO exhibits positive effect on both the elongation at break and melt strength. The results indicate that the blend obtained better rheological performance and melt strength. The content of 6 wt % ESO in PLA has been considered as a better balance of performance. The results have also demonstrated that there is a certain correlation between the performance in mechanical properties and melt rheological characterization for the PLA/ESO blends.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

17.
The linear and nonlinear shear rheological behaviors of poly(propylene) (PP)/clay (organophilic‐montmorillonite) nanocomposites (PP/org‐MMT) were investigated by an ARES rheometer. The materials were prepared by melt intercalation with maleic anhydride functionalized PP as a compatibilizer. The storage moduli (G′), loss moduli (G″), and dynamic viscosities of polymer/clay nanocomposites (PPCNs) increase monotonically with org‐MMT content. The presence of org‐MMT leads to pseudo‐solid‐like behaviors and slower relaxation behaviors of PPCN melts. For all samples, the dependence of G′ and G″ on ω shows nonterminal behaviors. At lower frequency, the steady shear viscosities of PPCNs increase with org‐MMT content. However, the PPCN melts show a greater shear thinning tendency than pure PP melt because of the preferential orientation of the MMT layers. Therefore, PPCNs have higher moduli but better processibility compared with pure PP.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2427–2434,2004  相似文献   

18.
The effects of natural rubber (NR) on the mechanical, thermal, and morphological properties of multiwalled carbon nanotube (CNT) reinforced poly(lactic acid) (PLA) nanocomposites prepared by melt blending were investigated. A PLA/NR blend and PLA/CNT nanocomposites were also produced for comparison. The tensile strength and Young's modulus of PLA/CNT nanocomposites improved significantly, whereas the impact strength decreased compared to neat PLA. The incorporation of NR into PLA/CNT significantly improved the impact strength and elongation at break of the nanocomposites, which showed approximately 200% and 850% increases at 20 wt % NR, respectively. However, the tensile strength and Young's modulus of PLA/NR/CNT nanocomposites decreased compared to PLA/CNT nanocomposites. The morphology analysis showed the homogeneous dispersion of NR particles in PLA/NR/CNT nanocomposites, while CNTs preferentially reside in the NR phase rather than the PLA matrix. In addition, the incorporation of NR into PLA/CNT lowered the thermal stability and glass‐transition temperature of the nanocomposites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44344.  相似文献   

19.
Partially acetylated cellulose nanofibers (CNF) were chemically extracted from sisal fibers and the performance of those CNF as nanofillers for polylactide (PLA) for food packaging applications was evaluated. Three PLA nanocomposites; PLA/CNF (cellulose nanofibers), PLA/CNC (nanocrystalline cellulose), and PLA/C30B (CloisiteTM 30B, an organically modified montmorillonite clay) were prepared and their properties were evaluated. It was found that CNF reinforced composites showed a larger decrease on oxygen transmission rate (OTR) than the clay‐based composites; (PLA/CNF 1% nanocomposite showed a 63% of reduction at 23°C and 50% RH while PLA/C30B 1% showed a 26% decrease) and similar behavior on terms of water vapor barrier properties with 46 and 43%, respectively of decrease on water vapor transmission rate at 23°C and 50% RH (relative humidity). In terms of mechanical and thermomechanical properties, CNF‐based nanocomposites showed better performance than clay‐based composites without affecting significantly the optical transparency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43257.  相似文献   

20.
Biodegradable polymer nanocomposites have been developed in this study as materials for use in the packaging of moisture‐sensitive products. Poly(lactic acid) (PLA) was the main component of the nanocomposites with poly(butylene adipate‐co‐terephthalate) (PBAT) as flexibility enhancer. Tetrabutyl titanate was also added as a compatibilizer to enhance the interfacial affinity between PLA and PBAT by inducing the formation of some PLA/PBAT via transesterification during the melt blending process, thereby improving the mechanical properties of the blends. Silver‐loaded kaolinite synthesized via chemical reduction was also incorporated into the compatibilized blends for further property improvement. Herein, we report a novel biodegradable quaternary nanocomposite system with intercalated‐exfoliated clay dispersion that was uniquely achieved by increasing the interlamellar space between kaolinite layers through silver nanoparticle insertion. The resultant nanocomposites containing as little as 4 phr modified clay reduced the elongation at break from 213.0 ± 5.85% to 53.8 ± 1.81%, enhanced thermal stability (initial decomposition temperature increased from 378 °C to 399 °C) and exhibited a water vapor permeability reduction of 41.85%. On the basis of these properties, the developed nanocomposites are considered to be promising candidates for use in bio‐packaging applications to replace non‐biodegradable and petro‐based plastics. © 2014 Society of Chemical Industry  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