Polyamide 6/polypropylene (PA6/PP = 70/30 parts) blends containing 4 phr (parts per hundred resin) of organically modified clay (organoclay) toughened with maleated styrene-ethylene-butylene-styrene (SEBS-g-MA) were prepared by melt compounding using co-rotating twin-screw extruder followed by injection molding. X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to characterize the structure of the nanocomposites. The mechanical properties of the nanocomposites were determined by tensile, flexural, and notched Izod impact tests. The single edge notch three point bending test was used to evaluate the fracture toughness of SEBS-g-MA toughened PA6/PP nanocomposites. Thermal properties were studied by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). XRD and TEM results indicated the formation of the exfoliated structure for the PA6/PP/organoclay nanocomposites with and without SEBS-g-MA. With the exception of stiffness and strength, the addition of SEBS-g-MA into the PA6/PP/organoclay nanocomposites increased ductility, impact strength and fracture toughness. The elongation at break and fracture toughness of PA6/PP blends and nanocomposites were increased with increasing the testing speed, whereas tensile strength was decreased. The increase in ductility and fracture toughness at high testing speed could be attributed to the thermal blunting mechanism in front of crack tip. DSC results revealed that the presence of SEBS-g-MA had negligible effect on the melting and crystallization behavior of the PA6/PP/organoclay nanocomposites. TGA results showed that the incorporation of SEBS-g-MA increased the thermal stability of the nanocomposite. 相似文献
A series of polyamide 6/polypropylene (PA6/PP) blends and nanocomposites containing 4 wt% of organophilic modified montmorillonite (MMT) were designed and prepared by melt compounding followed by injection molding. Maleic anhydride polyethylene octene elastomer (POEgMAH) was used as impact modifier as well as compatibilizer in the blend system. Three weight ratios of PA6/PP blends were prepared i.e. 80:20, 70:30, and 60:40. The mechanical properties of PA6/PP blends and nanocomposite were studied through flexural and impact properties. Scanning electron microscopy (SEM) was used to study the microstructure. The incorporation of 10 wt% POEgMAH into PA6/PP blends significantly increased the toughness with a corresponding reduction in strength and stiffness. However, on further addition of 4 wt% organoclay, the strength and modulus increased but with a sacrifice in impact strength. It was also found that the mechanical properties are a function of blend ratio with 70:30 PA6/PP having the highest impact strength, both for blends and nanocomposites. The morphological study revealed that within the blend ratio studied, the higher the PA6 content, the finer were the POEgMAH particles. 相似文献
Polylactide-based systems composed of an organoclay (Cloisite® 30B) and/or a compatibilizer (Exxelor VA1803) prepared by melt blending were investigated. Two types of not compatibilized nanocomposites containing 3 wt% or 10 wt% of the organoclay were studied to reveal the effect of the filler concentration on the nanostructure and physical properties of such systems. The 3 wt%-nanocomposite was also additionally compatibilized in order to improve the nanoclay dispersion. Neat polylactide and polylactide with the compatibilizer processed in similar conditions were used as reference samples. The X-ray investigations showed the presence of exfoliated nanostructure in 3 wt%-nanocomposite. Compatibilization of such system noticeably enhanced the degree of exfoliation of the organoclay. Viscoelastic spectra (DMTA) showed an increase of the storage and loss moduli with the increase of the organoclay content and dispersion. Dielectric properties of the nanocomposites show a weak influence of the nanoclay on segmental (αS) and local (β)-relaxations in PLA, except for the highest nanoclay content. Above Tg a strong increase of dc conductivity related to ionic species in the clay is observed. It gives rise also to the Maxwell-Wagner-Sillars interfacial polarization and both real and imaginary parts of ε strongly increase. In the temperature dependence of low frequency dielectric constant and mechanical moduli (at 1 Hz) an additional maximum around 80-90 °C is observed due to cold crystallization of PLA. 相似文献
Polypropylene (PP) blends with acrylonitrile-butadiene-styrene (ABS) were prepared using the styrene-ethylene-butylene-styrene copolymer (SEBS) as a compatibilizing agent. The blends were prepared in a co-rotational twin-screw extruder and injection molded. Torque rheometry, Izod impact strength, tensile strength, heat deflection temperature (HDT), differential scanning calorimetry, thermogravimetry, and scanning electron microscopy properties were investigated. The results showed that there was an increase in the torque of PA6/ABS blends with SEBS addition. The PP/ABS/SEBS (60/25/15%) blend showed significant improvement in impact strength, elongation at break, thermal stability, and HDT compared with neat PP. The elastic modulus and tensile strength have not been significantly reduced. The degree of crystallinity and the crystalline melting temperature increased, indicating a nucleating effect of ABS. The PP/ABS blends compatibilized with 12.5% and 15% SEBS presented morphology with well-distributed fine ABS particles with good interfacial adhesion. As a result, thermal stability has been improved over pure PP and the mechanical properties have been increased, especially impact strength. In general, the addition of the SEBS copolymer as the PP/ABS blend compatibilizer has the advantage of refining the blend's morphology, increasing its toughness and thermal stability, without jeopardizing other PP properties. 相似文献
Nanocomposites containing natural rubber (NR) as matrix, epoxidized natural rubber (ENR) as compatibilizer and organophilic layered clay (organoclay) as filler were produced in an internal mixer and cured using a conventional sulphuric system. The effects of ENR with 25 (ENR 25) and 50 mol% epoxidation (ENR 50), respectively, were compared at 5 and 10 parts per hundred rubber (phr) concentrations. The organoclay content was fixed at 2 phr. Cure characteristics, clay dispersion, (thermo)mechanical properties of the nanocomposites were determined and discussed. Incorporation of ENR and organoclay strongly affected the parameters which could be derived from Monsanto MDR measurements. Faster cure and increased crosslink density were attributed to changes in the activation/crosslinking pathway which was, however, not studied in detail. The organoclay was mostly intercalated according to X-ray diffraction (XRD) and transmission electron microscopic (TEM) results. The best clay dispersion was achieved by adding ENR 50. This was reflected in the stiffness of the nanocomposites derived from both dynamic mechanical thermal analysis (DMTA) and tensile tests. The tensile and tear strengths of the ENR 50 containing nanocomposites were also superior to the ENR 25 compatibilized and uncompatibilized stocks. 相似文献
The synergistic effects of layered double hydroxide (LDH) with hyperfine magnesium hydroxide (HFMH) in halogen-free flame retardant ethylene-vinyl acetate (EVA)/HFMH/LDH nanocomposites have been studied by X-ray diffraction (XRD), transmission electron spectroscopy (TEM), thermogravimetric analysis (TGA), limiting oxygen index (LOI), mechanical properties' tests, and dynamic mechanical thermal analysis (DMTA). The XRD results show that the exfoliated EVA/HFMH/LDH can be obtained by controlling the LDH loading. The TEM images give the evidence that the organic-modified LDH (OM-LDH) can act as a disperser and help HFMH particles to disperse homogeneously in the EVA matrix. The TGA data demonstrate that the addition of LDH can raise 5-18 °C thermal degradation temperatures of EVA/HFMH/LDH nanocomposite samples with 5-15 phr OM-LDH compared with that of the control EVA/HFMH sample when 50% weight loss is selected as a point of comparison. The LOI and mechanical tests show that the LDH can act as flame retardant synergist and compatilizer to apparently increase the LOI and elongation at break values of EVA/HFMH/LDH nanocomposites. The DMTA data verify that the Tg value (−10 °C) of the EVA/HFMH/LDH nanocomposite sample with 15 phr LDH is much lower than that (Tg = −2 °C) of the control EVA/HFMH sample without LDH and approximates to the Tg value (−12 °C) of pure EVA, which indicates that the nanocomposites with LDH have more flexibility than that of the EVA/HFMH composites. 相似文献
Summary: Polyamide 6 (PA6)/acrylonitrile‐butadiene‐styrene (ABS) (40/60 w/w) nanocomposites with a novel morphology were prepared by the melt mixing of PA6, ABS and organoclay. The blend nanocomposites had a co‐continuous structure, in which both PA6 and styrene‐acrylonitrile (SAN) were continuous phases. It was found that the toughening rubber particles were only located in the SAN phase and the strengthening clay platelets were selectively dispersed in the PA6 phase. The co‐continuous nanocomposites showed greatly improved mechanical properties over the whole temperature range when compared with the same blend sample without clay.
Schematic diagram for the co‐continuous ABS/PA6 blend nanocomposite. 相似文献
The nanocomposites of polyamide 6 (PA6)/poly(methyl methacrylate) (PMMA)/non-functionalized and functionalized [carboxylic acid (COOH) and hydroxyl (OH)] single wall carbon nanotubes (SWCNTs) were prepared in mass ratios of 79.5/19.5/1, 49.5/49.5/1, and 19.5/79.5/1 by melt–mixing method at 230 °C. The PA6/PMMA blends with mass ratios of 80/20, 50/50, and 20/80 served as references. The Fourier transform infrared analyses of nanocomposites showed the formation of hydrogen bond interactions among PA6, PMMA, and OH and COOH functional groups of SWCNTs. The nanocomposites and blends had higher thermal stability with respect to the PMMA. The differential scanning calorimeter (DSC) curves showed that the nanocomposites and blends exhibited two Tg values at around 51 and 126 °C for PA6 and PMMA, respectively. About 20 °C early crystallization was observed in nanocomposites compared to the blends. The dynamic mechanical analysis (DMA) results suggested that among all the compositions of blends and nanocomposites, storage modulus (E′) was higher for PMMA-rich blends and nanocomposites. At 25 °C, the E′ values were higher for blends and nanocomposites compared to the neat PA6. The tan δ curves indicated that the more heterogeneity of the hybrid nature resulted in PA6/PMMA/SWCNTs-OH or SWCNTs-COOH with 79.5/19.5/1 mass ratio nanocomposites compared to the PA6/PMMA with 80/20 mass ratio blend. The higher Tg values of PA6 and PMMA were observed in DMA studies compared to the DSC studies for PA6 and PMMA as neat and in blends and nanocomposites. The significant improvements in crystallization of nanocomposites were considered resulting from achieving better compatibility among the polymer components and carbon nanotubes. 相似文献
In this work blends of poly(ethylene-co-vinyl alcohol) (EVOH) with different ethylene contents (27, 32, 38 and 44 mol%) and poly(methyl methacrylate) (PMMA) were prepared by mechanical mixing in the melted state. The miscibility and melting behavior as a function of blend composition and the ethylene content in EVOH copolymers were investigated by means of differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The morphology of the cryofractured surfaces was examined by scanning electron microscopy (SEM). DSC and DMTA data show that EVOH/PMMA blends are immiscible, independent of EVOH and blend composition. The SEM analysis in agreement with DMTA analysis indicates that the morphology of phases depends on the blend composition, with phase inversion occurring as the concentration of one or other polymer component increases. However, the copolymer composition apparently does not affect the domain size distribution for blends containing 20 wt% of EVOH or 20 wt% of PMMA. A better phase adhesion is observed mainly for blends with 50 wt% of each polymer component. 相似文献
Among polyamide based blends, PA/PP alloys show interesting technological properties due to low moisture absorption. A model class of PA6/PP homopolymer blends, compatibilized through the addition of PP-g-MA is described in the present work; the experimentally obtained morphologies are related to predictive equations for co-continuity, at given rheological conditions. PP/compatibilizer ratio = 4/1 is found to impart an optimum level of phase dispersion. Moisture absorption, dimensional stability, mechanical properties and morphology are related with blend composition. 相似文献
Blends of poly(carbonate of bisphenol A) (PC) with minute amounts of a nanocomposite based in polyamide 6 (PA6) with a layered organoclay (nPA6) were obtained upon melt mixing by varying the contents of both nPA6 and organoclay. The ternary nanocomposites (NC) were composed of a PC-rich matrix with some mixed PA6 present, and by a neat nPA6 dispersed phase. Upon dissolution of the matrix of the NC’s, the dispersed phase showed a highly fibrillar morphology that resembled that of thermoplastic/liquid crystalline polymer (LCP) blends. The cryogenically fractured surfaces observed by SEM showed a very fine particle size that was attributed to the presence of PA6 in the matrix and indicated a low interfacial tension. The Young’s modulus behaviour is proposed to be a consequence of the slight orientation of the PC-rich matrix and the highly fibrillated and oriented nPA6 dispersed phase. The important reinforcement effect of the dispersed phase is attributed to the additive effects of its large degree of orientation, and the reinforcing effect of the organoclay. 相似文献
The paper presents differential scanning calorimetry and electron microscopy of the fractionated crystallization and polydispersity of the dispersed PA6 phase in compatibilized LDPE/PA6 75/25 w/w blends. The compatibilizers used were (i) an acrylic acid functionalized polyethylene, Escor 5001 (EAA); (ii) an ethylene-glycidylmethacrylate copolymer, Lotader GMA AX8840 (EGMA); (iii) a polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer comprising 2 wt.% maleic anhydride grafts, Kraton FG 1901X (SEBS-g-MA). The compatibilizer SEBS-g-MA has the strongest reduction effect upon the size of PA-6 droplets. Its implementation provides the best fractionated crystallization. The fractionated crystallization has not been observed for the blend compatibilized with EGMA. The results show that the degree of compatibilization could be evaluated qualitatively by the progress of the fractionated crystallization. So, the three compatibilizers could be rated according to their effectiveness as follows: SEBS-g-MA > EAA > EGMA. The self-nucleation experiments have demonstrated that the lack of active nuclei in the finely dispersed PA6 droplets is the determining factor for the fractionated crystallization at high supercooling, and not the considered absolute particle size. The measurement of the Vickers microhardness of the compatibilized blends confirms that the compatibilizing activity of SEBS-g-MA and EAA is stronger than that of EGMA. 相似文献
Styrene-ethylene-butylene-styrene block copolymer (SEBS)/clay nanocomposites were prepared via a melt mixing technique. Various amounts of two types of maleated compatibilizers, styrene-ethylene-butylene-styrene block copolymer grafted maleic anhydride (SEBS-g-MA) and polypropylene grafted maleic anhydride (PP-g-MA), were incorporated to improve the dispersion of commercial organoclay (denoted as 20A), respectively. PP-g-MA compatibilized system conferred higher tensile strength and tear strength (initiation condition) than SEBS-g-MA compatibilized system. At a fixed content of compatibilizers, the above mechanical properties were improved with increasing clay content as well. By relating tensile strength to tear strength (arrest condition), the average depth of flaw was in the range of 33.8 ± 3.4 μm, which successfully confirmed the extension of Rivlin and Thomas’s theory for conventional elastomers to thermoplastic elastomer/clay nanocomposites for the first time. Cutting strength of SEBS/clay nanocomposites gave an intermediate value when compared with crystalline plastics and conventional amorphous elastomers, which further signified the importance of micro-yielding of styrene domains, crystalline yielding of compatibilizer, and filler reinforcement even in the nano-fracture zone of deformation. 相似文献
Influence of microstructure on impact toughness and fracture behavior of PA6 and EBA blends reactively compatibilized by EBA-g-MAH was quantitatively studied. The reactively compatibilized blends showed better distribution of elastomeric EBA particles in the PA6 matrix and the presence of EBA-g-MAH resulted in considerable reduction of interfacial tension between the component polymers. The interfacial adhesion between the PA6 and EBA phase in the compatibilized blends was enhanced by the interfacial reaction between the amide end-groups of PA6 and maleic anhydride group of EBA-g-MAH compared to uncompatibilized blends. The matrix ligament thickness and particle diameter values were lower than the predicted critical values and were responsible for the ductile behavior of the compatibilized blends. Stress whitening around the notch occurred in all the compatibilized blends which was the major energy dissipation zone in the blends. Matrix shear yielding or plastic flow without crazing was the dominant deformation mechanism in the tough compatibilized blends. There was no sign of shear yielding during impact fracture of the uncompatibilized blends where the elastomeric particles were completely dislodged from the matrix. 相似文献