Effects of preferential encapsulation of glass fiber on the properties of ternary GF/PA/PP blends

Long fiber molding materials are expected to play an important role in the near future. This paper describes a series of experiments performed to examine properties of ternary blends containing glass fiber (GF), polyamide (PA), and polypropylene (PP). The continuous glass fiber was impregnated with one of the blend constituent polymers by our specially designed impregnation apparatus and cut into chips of 6 mm length. These chips and the other polymer were used to produce various testing specimens in a twin screw extruder or in injection molding machine. The results indicated that the effect of fiber addition on the mechanical and rheological properties is clearly dependent on the order of impregnation process. In the blends containing the GF/PA + PP, the GFs are preferentially encapsulated with PA, and therefore the mechanical properties are superior to the blends with the GF/PP + PA in which the PP phase is located surrounding the GFs. This improved wetting of fibers by sequential impregnation not only resulted in better properties but also protected the fibers from shear action of the screw, thereby allowing significant increase in average fiber length to be achieved in the injection molding process.     

Interface evaluation in the ternary blends of HDPE/PA-6/EVOH

In this work, a quantitative evaluation on interface situation in HDPE/PA-6/EVOH ternary blends is presented. For this purpose, binary and ternary blends based on HDPE as continuous phase and PA-6 and EVOH as minor components with different weight ratios were prepared. The morphology of the blends was studied by SEM and their mechanical properties were measured. Then, through a theoretical/experimental approach, the tensile characteristics of HDPE/PA-6/EVOH ternary blends are discussed. The interface situation in the prepared blends is probed in such a manner that phenomenological models are successfully extended to the case of ternary blends and their parameters are obtained using available predictive schemes. In addition, the stress–strain curves of all prepared binary and ternary blends comprising different PA-6 to EVOH weight ratios in the minority phase are taken into account to study the yielding and toughening phenomena followed by quantitative evaluation of interfacial adhesion. The results provided support for the fact that the yielding behavior of prepared ternary blends is dependent on the minor component fraction possibly due to the formation of voids at the interface of polymers.     

Mechanical, rheological, and thermal behavior assessments in HDPE/PA-6/EVOH ternary blends with variable morphology

Visco-elastic and dielectric spectra of multiwalled carbon-nanotube reinforced silicon elastomer nanocomposites were used to study relaxation behavior. SEM photomicrographs shows well dispersion of MWCNT in elastomer matrix. In visco-elastic analysis primary relaxation was studied as a function of temperature (?100 to 100 °C) at frequency 1Hz and strain 1 %. The effect of MWCNT loadings on storage modulus, loss modulus, and loss tangent has been studied. The non-linearity in loss tangent, storage modulus and loss modulus was explained on the basis of MWCNT-elastomer interaction and the inter-aggregate attraction of MWCNT. The secondary β relaxation was studied using dielectric relaxation spectra in the frequency range of 0.1 Hz to 10⁶ Hz. The effect of MWCNT loadings on the complex and real parts of impedance was distinctly visible which has been explained on the basis of interfacial polarization of fillers in a heterogeneous medium and relaxation dynamics of polymer chains in the vicinity of fillers. The dielectric formalism has been utilized to further investigate the conductivity and relaxation phenomenon. The ‘percolation limit’ of the MWCNT in the silicon elastomer was found to be in the range of 4 phr loading.     

Dynamic rheological properties of binary PP/PA and ternary PP/PA/GF blends

The dynamic rheological behavior was investigated for binary polypropylene (PP) - polyamide-6 (PA-6) and ternary PP-PA-6-glass fiber (GF) blends. The observed trends are related to the blend morphology and the partitioning of the GF within the three component blends. The dynamic and shear viscosity results show a good overlap for the PP homopolymer, within the shear rates studied. The addition of PA-6 and/or glass fibers to the PP causes significant deviations between the two rheological behaviors. This reflects the fibrillation of PA-6 and the orientation of glass fibers during shear rheometry, which reduce the blends' shear viscosity. The effect of PA-6 content on dynamic viscosity is less significant than for shear viscosity, owing to the absence of morphological structuring. The addition of PA-6 to PP increased the principal relaxation time of the binary blends. The addition of GF to these binary blends gave a further increase in the principal relaxation time.     

Morphology and properties of PP/EPDM binary blends and PP/EPDM/nano‐CaCO3 ternary blends

In this article, the morphology, crystallization, and rheological behaviors of polypropylene (PP)/ethylene‐propylene‐diene terpolymer (EPDM) binary blend and PP/EPDM/calcium carbonate nanoparticles (nano‐CaCO₃) ternary blend were investigated. Two processing methods, i.e., direct extrusion and two‐step extrusion, were employed to prepare the PP/EPDM/CaCO₃ blend. The influence of EPDM and nano‐CaCO₃ respectively on phase morphology and properties of PP/EPDM blend and PP/EPDM/CaCO₃ blend were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and dynamic rheometer. The crystallinity and crystallization temperature of PP/EPDM blend were improved in comparison to pure PP due to addition of EPDM, but kept invariable with the increased EPDM loading. As the EPDM content was increased, the mobility of PP molecular chains was weakened. Compared with direct extruded blend, less and finer nano‐CaCO₃ was dispersed in matrix of two‐step extruded blend. Accordingly, the increased nano‐CaCO₃ in matrix gave rise to a weaker increment in crystallinity and crystallization temperature of two‐step extruded blend, and a later platform of tanδ curve. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

纳米双羟基复合金属氧化物协同聚磷酸铵阻燃尼龙-6/聚丙烯燃烧及热降解行为的研究

将纳米双羟基复合金属氧化物 (LDH)与聚磷酸铵 (APP)在一定范围内复配 ,用于尼龙 6/聚丙烯 (PA 6/PP)共混体系可产生良好的协同阻燃效果。实验表明 ,LDH参与了共混阻燃体系的热分解反应 ,催化了PA 6/PP/APP体系的交联、成炭 ;LDH协同阻燃体系的残炭形态致密、光滑、残炭微孔呈闭合状态。协同阻燃作用的机理与LDH和APP热降解过程中产物间的化学与物理作用有关。     

Morphology and properties of PET/PA-6/E-44 blends

Polymer blends incorporating poly (ethylene terephthalate) (PET), polyamide-6 (PA-6), and a reactive compatibilizer (low molecular weight bisphenol-A epoxy resin—E-44) were prepared with the following E-44 weight percent concentrations: 0, 0.3, 0.6, 1, 3, 5, and 10. The samples was studied by a scanning electron microscope (SEM), a polarizing microscope (PLM), dynamic mechanical thermal analysis (DMTA), wide-angle X-ray diffraction (WAXD), a differential scanning calorimeter (DSC), infrared spectroscopy (IR), and mechanical testing. SEM and PLM showed noticeable changes in both the amorphous region and the crystalline region of the blends. The changes indicated better compatibility between the dispersed phase (PA-6) and the matrix (PET), which was further confirmed by the DMTA test. The WAXD showed that PET and PA-6 crystallized separately and no cocrystallite was found. The melting and crystallization data, obtained by DSC, suggested that the crystallization of the blend was blocked, although the hindered mechanism for the effect of E-44 on PET was different from that on PA-6. The notched impact strength and flexural strength of the PET/PA-6 blends were significantly improved when the content of E-44 was 5 wt % (improved about 500 and 400%, respectively). IR was used to study the reaction among E-44, PET, and PA-6. The result indicated that the grafting reaction and the crosslinking reaction occurred during melt blending. The obvious increase of mechanical properties and the reinforcing and toughening effect were attributed to the formation of the crosslinking net in the blend. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1505–1515, 1998     

Impact fracture behavior of PP/EPDM/glass bead ternary composites

The effects of glass bead filler content and surface treatment of the glass with a silane coupling agent on the room temperature impact fracture behavior of polypropylene (PP)/ethylene‐propylene‐diene monomer copolymer (EPDM)/glass bead(GB) ternary composites were determined. The volume fraction of EPDM was kept constant at 10%. The impact fracture energy and impact strength of the composites increased with increasing volume fraction of glass beads (?_g). Surface pretreatment of the glass beads had an insignificant effect on the impact behavior. For a fixed filler content, the best impact strength was achieved when untreated glass beads and a maleic anhydride modified EPDM were used. The impact strength exhibited a maximum value at ?_g=15%. Morphology/impact property relationships and an explanation of the toughening mechanisms were developed by comparing the impact properties with scanning electron micrographs of fracture surfaces.     

PET/EVA/PP ternary blends: An investigation of extended morphological properties

In this study, the effects of different parameters on the morphological properties of ternary blends were investigated. Therefore two systems (PET/H‐EVA/PP and PET/L ‐EVA/PP, H‐EVA and L ‐EVA are high and low viscosity, respectively) were prepared by melt mixing process. In all of the blends, poly (ethylene terephthalate) (PET) as the major phase‐ with poly propylene (PP) and two grades of poly (ethyl‐stat‐vinylacetate) (EVA) with different viscosities and subsequently different interfacial interactions was blended. Theoretical models predicted positive spreading coefficient for two grades of EVA and lower free energy for the samples consisting of EVA and PP as the shell and the core phases respectively. With changing core shell ratio, droplet size of samples containing L ‐EVA and H‐EVA increased and decreased, respectively. Subinclusion of shell into the core was observed in some blended samples. In systems containing H‐EVA, by thickening the shell phase; multi core morphology was observed which would be related to the coalescence phenomenon inter the droplets. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Tensile properties and morphology of PP/EPDM/glass bead ternary composites

The tensile properties of three types of injection molded glass bead (GB) filled polypropylene (PP)/ethylene-propylene-diene monomer (EPDM) ternary composites have been determined at room temperature by using an Instron materials testing machine. The effects of the filler surface treatment, the glass bead (GBI) pretreated with a silane coupling agent and the EPDM (EPDM-MA) modified with a maleic anhydride, and the filler content on the tensile mechanical properties of the ternary PP composites have been investigated. The Young's modulus (E_c) increases while the yield stress (σ_yc) and tensile fracture strength (σ_bc) of the composites decrease with increasing the volume fraction of glass beads (ϕ_g) when the volume fraction of EPDM is constant (ϕ_e = 10%). The (E_c) values of PP/EPDM/GBI and ϵ_bc for PP/EPDM-MA/GB2 (no surface pretreated) systems are the highest at the same ϕ_g. The tensile fracture energy (E_bc) and tensile fracture strain (ϵ_bc) of PP/EPDM/GBI and PP/EPDM/GB2 systems appear to peak at ϕ_g = 25%. However, the E_bc and ϵ_bc of PP/EPDM-MA/GB2 system show little changes with increasing ϕ_g. The fracture surfaces of ternary composites have been examined in a scanning electron microscope. The correlation between the tensile properties and morphologies of these materials have been discussed.     

PP/PA6/POE-g-MAH三元共混对聚丙烯熔体强度的影响

将尼龙6(PA6)、普通聚丙烯(PP)以及POE-g-MAH三元共混,改善聚丙烯的熔体强度。应用熔体强度测试仪直接测量了改性PP的熔体强度值,并对改性PP的动态流变特性、红外光谱以及微观形貌特点进行了研究。研究结果表明,该方法可以提高聚丙烯熔体强度。     

Effects of compatibilization of oxidized polypropylene on PP blends of PP/PA6 and PP/talc

The influence of compatibilization on the dynamic mechanical properties of polypropylene (PP) binary blends with polyamide‐6 (PA6), Talc, and oxidized PP (OPP) was investigated. The oxidation of PP homopolymer was performed in a internal mixer by using air as a oxidizing agent (under atmospheric pressure) and dodecanol‐1 as an accelerator at 180°C for 6½ h [Abdouss, M.; Sharifi‐Sanjani, N.; Bataille, P. J Appl Polym Sci 1999, 36, 10]. In the blends, OPP was used as a blend component and compared with PP over the whole concentration range. Pressed film blends of PP/OPP, PP/OPP/Talc, and PP/OPP/PA6 were examined by dynamic mechanical analyzer, thermal gravimetry analysis, and scanning electron microscopy. Mechanical properties such as tensile strength, modulus of elasticity, elongation, melt flow index, and hardness of the blends were measured. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2871–2883, 2004     

PP／PA—6合金的力学性能与相态结构

通过对ＰＰ／ＰＡ＝６合金的相态结构及力学性能的研究，发现ＰＰ／ＰＡ－６合 相态结构与是加入相容剂有关，屈服强度是合金中ＰＡ－６的体积含量的函数，缺口冲击强度主要取决于分散相颗粒表面间距，并且可以用经验公式描述。     

Post-yield fracture behaviour of PA-6/LDPE-g-MA/nanoclay ternary nanocomposites: semiductile-to-ductile transition

The relationship between the stereo-defect distribution and the crystallization behavior of Ziegler-Natta isotactic polypropylene (ZN-iPP) is an important issue, which has not been clearly studied up to now. In this work, the crystallization behavior of a series of iPP samples with similar average isotacticity but different stereo-defect distribution, polymerized with the same Ziegler-Natta catalyst system, was studied by means of differential scanning calorimetry (DSC) and polarized optical microscopy (POM) observation. The results of isothermal crystallization kinetics indicated that, as the distribution of stereo-defects becomes more uniform, the overall crystallization rate decreases gradually. Meanwhile, the results of self-nucleation isothermal crystallization kinetics showed that, the crystal growth rate decreases gradually and the energy barrier of crystal growth increases. Moreover, the POM observation illustrated that not only the crystal growth rate, but also the nucleation rate decrease gradually as the stereo-defect distribution becomes more uniform. The results above indicated that for iPP polymerized with the same Ziegler-Natta catalyst system, stereo-defect distribution plays an important role in determining the nucleation kinetics, crystal growth kinetics and the overall crystallization kinetics of the resin.     

Compatibilization of PP/PBT and PP/PA6 blends with a new oxazoline-functionalized polypropylene

Summary Aim of this work was to study the effectiveness of a novel oxazoline-functionalized polypropylene as a compatibilizer for PP/PBT and PP/PA6 blends. This polypropylene-based compatibilizer mixes well with the polypropylene and is capable of reacting with the carboxylic and amine end groups of PBT and PA6. Significant improvements in blend toughness were achieved without reduction in strength and stiffness. These effects were related to stabilized morphology of finely dispersed minor phase well attached to the matrix. The enhanced interfacial interactions between the two phases, in particular at high PBT content were evidenced by increased melt viscosity.     

Rheological properties,tensile properties,and morphology of PP/EPDM/lonomer ternary blends

The rheological and tensile properties and the morphology of polypropylene (PP)/ethylenepropylene-diene terpolymer(EPDM)/ionomer ternary blends were investigated, using a rheometric dynamic spectrometer (RDS), a dynamic mechanical thermal analyzer (DMTA), a tensile tester, and a scanning electron microscope (SEM). Two kinds of poly(ethylene-co-methacrylic acid) (EMA) ionomers, neutralized with different metal ions (Na⁺ and Zn⁺⁺), were used. Blends were melt-mixed, using a laboratory internal mixer at 190°C. The composition of PP and EPDM was fixed at 50/50 by wt % and the EMA ionomer contents were varied from 5 to 20 wt %, based on the total amount of PP and EPDM. It was found that the ternary blends, containing Na-neutralized ionomer, showed considerably different rheological properties and morphology as compared to the PP/EPDM binary blends, due to the compatibilizing effect of the ionomer for PP and EPDM, while the ternary blends, containing the Zn-neutralized ionomer, did not. The compatibilizing effect was most prominent at 5 wt % ionomer concentration. © 1994 John Wiley & Sons, Inc.     

弹性体接枝马来酸酐对PP/PA6 的增容作用

以4种弹性体接枝马来酸酐(MAH)共聚物作为聚丙烯/聚酰胺6(PP/PA6)共混体系的增容剂,从界面相互作用、形态结构和力学性能等方面比较了它们的增容作用。乙烯-辛烯共聚物接枝马来酸酐(POE-g-MAH)和乙丙三元共聚物接枝MAH(EPDM-g-MAH)使PP与PA6两相间的界面相互作用增强,增容效果较好;POE-g-MAH为增容剂时,PA6粒子分布较均匀,粒径约为1μm。POE-g-MAH能明显改善PP/PA6共混体系的韧性和强度,具有良好的增容作用。当w(POE-g-MAH)为10%时,w(PA6)为60%的共混体系拉伸强度最高,达到53.4MPa;适当增加PA6用量,可明显改善共混体系的流动性。     

Studies on fracture behavior of tough PA6/PP blends

Fracture toughness of injection-molded PA6/PP blends compatibilized with SEBS-g-MA was studied using deeply double-edge notched tension (DDENT) specimens according to the essential work of fracture procedure. The fracture mechanical studies also included tensile impact tests on the DDENT specimens and characterization of the fracture surfaces by electron microscopy. The results were compared with those of traditional tensile tests and Izod impact tests on single-edge notched samples, and the sensibility of the methods was evaluated. Effects of sample position, ligament length, testing direction, and test speed were studied as well. It was found that the essential work of fracture concept, earlier applied to thin sheets, can also be applied to injection-molded tough blends. High deformation of the skin may, however, interfere with the measurements and cause a “tail” in the load-deformation curves. The plastic work of fracture (w_p) was found to correlate with the impact strength, and thus, it described the toughness. The highest values for work of fracture were recorded for the compatibilized blend with a PA6/PP ratio of 80/20. The essential work of fracture (w_e) in turn increased with increasing PA6 content and behaved like tensile strength. The test speed was found to affect the fracture behavior substantially: differences between the materials were more pronounced in high-speed tensile impact tests, which revealed signs of cavitation in addition to large-scale plastic deformation for the tough PA6-rich blend compositions. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2209–2220, 1997     

Tensile properties and morphology of the dynamically cured EPDM and PP/HDPE ternary blends

The tensile properties and morphology of the polyolefin ternary blends of ethylenepropylene–diene terpolymer (EPDM), polypropylene and high density polyethylene were studied. Blends were prepared in a laboratory internal mixer where EPDM was cured in the presence of PP and HDPE under shear with dicumyl peroxide (DCP). For comparison, blends were also prepared from EPDM which was dynamically cured alone and blended with PP and HDPE later (cure–blend). The effect of DCP concentration, intensity of the shear mixing, and rubber/plastics composition was studied. The tensile strength and modulus increased with increasing DCP concentration in the blends of EPDM-rich compositions but decreased with increasing DCP concentration in blends of PP-rich compositions. In the morphological analysis by scanning electron microscopy (SEM), the small amount of EPDM acted as a compatibilizer to HDPE and PP. It was also revealed that the dynamic curing process could reduce the domain size of the crosslinked EPDM phase. When the EPDM forms the matrix, the phase separation effect becomes dominant between the EPDM matrix and PP or HDPE domain due to the crosslinking in the matrix.