Mechanical properties and morphological structures of short glass fiber reinforced PP/EPDM composite

The mechanical properties and crystal morphological structures of short glass fiber (SGF) reinforced dynamically photo-irradiated polypropylene (PP)/ethylene-propylene-diene terpolymer (EPDM) composites were studied by mechanical tests, wide-angle X-ray diffraction (WAXD), optical microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA). The mechanical properties of PP/EPDM composites, especially the tensile strength were greatly strengthened by dynamically photo-irradiation and the incorporation of SGF. The results from the WAXD, SEM, DSC, and TGA measurements reveal: (i) the formation of β-type crystal of PP in the PP/EPDM/SGF composite; (ii) the fiber length in dynamically photo-irradiated PP/EPDM/SGF composites are general longer than that in corresponding unirradiated samples. The size of EPDM phase in the photo-irradiated composites reduces obviously whereas the droplet number increases; (iii) photo-irradiation improves the interface adhesion between SGF and polymer matrix; (iv) the melting and crystallization temperatures of the photo-irradiated composites are not affected greatly by increasing the SGF content; (v) the thermal analysis results show that the incorporation of SGF into PP/EPDM plays an important role for increasing its thermal stability.     

Morphology and mechanical behavior of isotactic polypropylene with different stereo‐defect distribution in injection molding

Large amount of work has been published on the isotacticity–properties relationship of isotactic polypropylene (iPP). However, the stereo‐defect distribution dependence of morphology and mechanical properties of iPP injection molding samples is still not clear. In this study, two different isotactic polypropylene (iPP) resins (PP‐A and PP‐B) with similar average isotacticity but different stereo‐defect distribution were selected to investigate the morphology evolution and mechanical properties (tensile and notching) of their injection molding samples using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), 2D wide angle X‐ray diffraction (2D‐WAXD), and scanning electron microscope (SEM). The results of DMA showed that the molecular movement ability of PP‐A (with less uniform distribution of stereo‐defect) was stronger than that of PP‐B, meanwhile the analysis of DSC and SEM suggested that after injection molding, smaller spherullites, and crystals with higher perfection had formed in the specimens of PP‐A. The resulting of tensile properties of PP‐A were found to be better than that of PP‐B. The results of morphology evolution by SEM observation and 2D‐WAXD showed that PP‐A is more likely to occur interspherulite deformation and can disperse the tensile stress more efficiently, and therefore, its crystal structure can withstand a greater force when tensile stress is applied. On the other hand, PP‐B has larger spherulites and boundaries, and low perfection of lamellaes, and the intraspherulte deformation tend to take place. It is easier for the crystal of PP‐B to be broken up and reoriented along the tensile direction. Copyright © 2014 John Wiley & Sons, Ltd.     

Preparation and enhanced properties of poly(propylene)/ silica‐grafted‐hyperbranched polyester nanocomposites

A series of poly(propylene) silica‐grafted‐hyperbranched polyester nanocomposites by grafting the modified hyperbranched polyester (Boltorn? H20), possessing theoretically 50% end carboxylic groups and 50% end hydroxyl groups, which endcapped with octadecyl isocyanate (C19), onto the surface of SiO₂ particles (30 nm) through 3‐glycidoxy‐propyltrimethoxysilane (GPTS) was prepared. The effect of silica‐grafted‐modified Boltorn? H20 on the mechanical properties of polypropylene (PP) was investigated by tensile and impact tests. The morphological structure of impact fracture surface and thermal behavior of the composites were determined by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The melt viscosity of composites was investigated by melt flow index (MFI). The obtained results showed that: (1) the modified Boltorn? H20 was successfully grafted onto the SiO₂ surface confirmed by FT‐IR and X‐ray photoelectron spectroscopy (XPS) analysis; (2) the incorporation of silica‐grafted‐modified Boltorn? H20 (3–5 wt% SiO₂) greatly enhanced the notched impact strength as well the tensile strength of the composites; (3) the incorporation of silica‐grafted‐modified Boltorn? H20 had no influence on the melting temperature and crystallinity of PP phase; (4) the MFI of PP composites increased when the silica‐grafted‐modified Boltorn? H20 particles were added compared with PP/SiO₂ or PP/SiO₂‐GPTS composites. Copyright © 2004 John Wiley & Sons, Ltd.     

Structural and morphological studies on the deformation behavior of polypropylene/multi‐walled carbon nanotubes nanocomposites prepared through ultrasound‐assisted melt extrusion process

Structural and morphological behavior under stress–strain of polypropylene/multi‐walled carbon nanotubes (PP/MWCNTs) nanocomposites prepared through ultrasound‐assisted melt extrusion process was studied by means of optical microscopy, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, small angle X‐ray scattering (SAXS), and wide angle X‐ray scattering (WAXS). A high ductile behavior was observed in the PP/MWCNT nanocomposites with low concentration of MWCNTs. This was related to an energy‐dissipating mechanism, achieved by the formation of an ordered PP‐CNTs interphase zone and crystal oriented structure in the undeformed samples. Different strain‐induced‐phase transformations were observed by ex situ SAXS/WAXS, characterizing the different stages of structure development during the deformation of PP and PP/MWCNTs nanocomposites. The high concentration of CNTs reduced the strain behavior of PP due to the agglomeration of nanoparticles. A structural pathway relating the deformation‐induced phase transitions and the dissipation energy mechanism in the PP/MWCNTs nanocomposites at low concentration of nanoparticles was proposed. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 475–491     

Dynamically Photocrosslinking of Polypropylene／EPDM Blends as a Thermoplastic Elastomer

The mechanical properties and the crystal morphological structures of the dynamically photocrosslinked polypropylene (PP)/ethylene-propylene-diene terpolymer (EPDM) blends have been studied by means of mechanical tests, wide-angle X-ray diffraction(WAXD), and differential scanning calorimetry(DSC). The dynamically photocrosslinking of the PP/EPDM blends can improve the mechanical properties considerably, especially the notched Izod impact strength at low temperatures. The data obtained from the mechanical tests show that the notched Izod impact strength of the dynamically photocrosslinked sample with 30% EPDM at -20℃ is about six times that of the uncrosslinked sample with the same EPDM component. The results from the gel content, the results of WAXD, and the DSC measurements reveal the enhanced mechanism of the impact strength for the dynamically photocrosslinked PP/EPDM blends as follows: (1) There exists the crosslinking of the EPDM phase in the photocrosslinked PP/EPDM blends ; (2) The β-type crystal structureof PP is formed and the content of α-type crystal decreases with increasing the EPDM component; (3) The graft copolymer of PP-g-EPDM is formed at the interface between the PP and EPDM components. All the above changes of the crystal morphological structures are favorable for increasing the compatibility and enhancing the toughness of the PP/EPDM blends at low temperatures.     

Selective distribution,reinforcement, and toughening roles of MWCNTs in immiscible polypropylene/ethylene‐co‐vinyl acetate blends

Polypropylene/ethylene‐co‐vinyl acetate (PP/EVA) nanocomposites with functionalized multiwalled carbon nanotubes (FMWCNTs) have been prepared. The dissolution experiment, transmission electronic microscope, and scanning electronic microscope characterizations prove that, in the nanocomposites with sea–island morphology, although some FMWCNTs are observed in both PP and EVA phases, most of FMWCNTs distribute at the interface; however, in the nanocomposites with cocontinuous morphology, FMWCNTs mainly distribute in EVA phase. Further results based on (differential scanning calorimetry) measurements show that the different dispersion states of FMWCNTs, which are resulted by the different melt blending sequences, result in the different crystallization behaviors of PP matrix. The mechanical measurements show that FMWCNTs exhibit apparent reinforcement and toughening effects for immiscible PP/EVA blends, and such effects are greatly dependent upon the blending sequences. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1882–1892, 2010     

Morphology and properties of polypropylene/ethylene–octene copolymer/clay nanocomposites with double compatibilizers

The influence of nanoclay on the morphology and properties of the polypropylene (PP)/ethylene–octene block copolymer (EOC) blend with double compatibilizers of maleated PP (PP‐g‐MA) and maleated EOC (EOC‐g‐MA) was investigated and compared with the nanocomposites containing either PP‐g‐MA or EOC‐g‐MA as a compatibilizer. X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy were utilized for morphological characterization in conjunction with dynamic mechanical thermal analysis, mechanical testing, and rheological evaluation of these nanocomposites. The results suggested that in the nanocomposite including both compatibilizers of PP‐g‐MA and EOC‐g‐MA, clay was dispersed as a mixed structure of intercalation and exfoliation in both phases of the polymer blend. Comparing the mechanical properties of the studied nanocomposite with nanocomposites of PP/EOC/PP‐g‐MA/clay and PP/EOC/EOC‐g‐MA/clay also indicated that the nanocomposite containing mixed compatibilizers displayed higher tensile modulus, tensile strength, and complex viscosity because of the better dispersion of clay in both phases. The results also confirmed the increased structural stability and reduced dispersed phase size of PP/EOC/PP‐g‐MA/EOC‐g‐MA blend in the presence of clay that proposed the compatibilization role of clay in this nanocomposite. Copyright © 2014 John Wiley & Sons, Ltd.     

Uncross‐linked polypropylene (PP)/ethylene‐propylene‐diene (EPDM)/multi walled carbon nanotube (MWCNT) and dynamically vulcanized PP/EPDM/MWCNT nanocomposites

In this study, relatively large amounts of polypropylene (PP), ethylene‐propylene‐diene (EPDM), and multi‐walled carbon nanotube (MWCNT) were melt‐mixed with and without DCP. Dynamically vulcanized PP/EPDM (TPV)/MWCNT nanocomposites were prepared by two methods: the MWCNTs were added either before or after the dynamic vulcanization of the blends. The effects of composition, rotor speed, and dynamic vulcanization on their surface resistivity were investigated. The surface resistivity of uncross‐linked PP/EPDM/MWCNT nanocomposites increases with increasing the content of EPDM. At PP/EPDM (70/30 wt%) nanocomposite with 1.5 phr MWCNT, slightly lower surface resistivity is obtained by increasing the rotor speed during mixing. However, for PP/EPDM (50/50 wt%) and PP/EPDM (30/70 wt%) nanocomposites, surface resistivity decreases with increasing the rotor speed from 30 to 60 rpm. But further increase in rotor speed (90 rpm) leads to an increase of surface resistivity. When the MWCNTs were added after the dynamic vulcanization of the blends, the surface resistivity of TPV70/MWCNTnanocomposite is lower than that of uncross‐linked PP/EPDM/MWCNT nanocomposite. However, when the MWCNTs were added before the dynamic vulcanization of the blends, the surface resistivity of TPV70/MWCNT nanocomposite is >10¹² Ω/square. Copyright © 2010 John Wiley & Sons, Ltd.     

Preparation and characterization of polyoxymethylene‐copolymer/hydroxyapatite nanocomposites for long‐term bone implants

In this work, new polyoxymethylene (POM)/hydroxyapatite (HAp) nanocomposites for long‐term bone implants have been obtained via extrusion and injection molding processes and characterized by differential scanning calorimetry (DSC), temperature‐modulated DSC (TMDSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), wide‐angle X‐ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), and tensile mechanical and in vitro stability tests. Based on the DSC results, it was found that the degree of crystallinity increases for POM/0.5% HAp sample and decreases for POM/1.0% HAp and POM/2.5% HAp. SEM and TEM observations for POM/HAp nanocomposites indicated that the dispersion of HAp in the polymer matrix was uniform and the diameter of the HAp particles was less than 100 nm for most of them. Young's modulus increases with increasing HAp concentration, whereby elongation at break decreases. On the contrary, HAp concentration does not have a significant influence on the tensile strength. TG results show that for POM/0.5% HAp, POM/1.0% HAp, and POM/2.5% HAp, thermal stability slightly increases in comparison to pure POM, whereas for POM/5.0 HAp and POM/10.0% HAp, lower thermal stability was observed. In vitro data reveal that with an increase of HAp content, bioactivity of nanocomposites increases; a good in vitro chemical stability of POM and POM nanocomposites was confirmed. Copyright © 2011 John Wiley & Sons, Ltd.     

Isothermal crystallization kinetics of polypropylene latex–based nanocomposites with organo‐modified clay

The effect of organo‐modified clay (Cloisite 93A) on the crystal structure and isothermal crystallization behavior of isotactic polypropylene (iPP) in iPP/clay nanocomposites prepared by latex technology was investigated by wide angle X‐ray diffraction, differential scanning calorimetry and polarized optical microscopy. The X‐ray diffraction results indicated that the higher clay loading promotes the formation of the β‐phase crystallites, as evidenced by the appearance of a new peak corresponding to the (300) reflection of β‐iPP. Analysis of the isothermal crystallization showed that the PP nanocomposite (1% C93A) exhibited higher crystallization rates than the neat PP. The unfilled iPP matrix and nanocomposites clearly shows double melting behavior; the shape of the melting transition progressively changes toward single melting with increasing crystallization temperature. The fold surface free energy (σ_e) of polymer chains in the nanocomposites was lower than that in the PP latex (PPL). It should be reasonable to treat C93A as a good nucleating agent for the crystallization of PPL, which plays a determinant effect on the reduction in σ_e during the isothermal crystallization of the nanocomposites. The activation energy, ΔE_a, decreased with the incorporation of clay nanoparticles into the matrix, which in turn indicates that the nucleation process is facilitated by the presence of clay. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1927–1938, 2010     

Preparation and characterization of vinylidene chloride‐co‐vinyl chloride copolymer/fluorinated synthetic mica nanocomposites I thermal and mechanical properties studies

Poly(vinylidene chloride‐co‐vinylchloride)/organically modified fluorinated synthetic mica (MEE) (VDC‐VC/MEE) nanocomposites were prepared by melt blending of VDC‐VC copolymer with MEE, in the presence of dioctyl phthalate (DOP) which acted as a plasticizer and a cointercalating agent. The nanostructure, thermal, and dynamic mechanical properties of the VDC‐VC/MEE nanocomposites were studied by wide angle X‐ray diffractometer (WAXD), scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analyzer (TGA), and dynamic mechanical analyzer (DMA). It was found that partially intercalated and partially exfoliated structures coexisted in VDC‐VC/MEE nanocomposities. Below 8 wt % MEE content, the intercalation effect of nanocomposites decreased with increasing the MEE content. Under a nitrogen atmosphere, VDC‐VC/MEE nanocomposites exhibited a single step thermal degradation behavior. The nanostructure of VDC‐VC/MEE can effectively prevent volatile gases from being released, and thus enhances its thermal stability. The thermal stability of VDC‐VC/MEE nanocomposites is strongly related to the morphology of nanocomposites and the degraded composites structure. DMA revealed a significant improvement in the storage modulus within the testing temperature range. The increase in storage modulus depends on the MEE content, which is attributed to the dispersed phase morphology. The glass transition temperature of VDC‐VC/MEE nanocomposites is affected by the chain mobility in the nanocomposites rather than the aggregative morphology. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1214–1225, 2008     

Isotactic Poly(propylene)/Monoalkylimidazolium‐Modified Montmorillonite Nanocomposites: Preparation by Intercalative Polymerization and Thermal Stability Study

Summary: Poly(propylene)/monoalkylimidazolium‐modified montmorillonite (PP/IMMT) nanocomposites were prepared by in situ intercalative polymerization of propylene with TiCl₄/MgCl₂/MMT catalyst. The PP synthesized possessed high isotacticity and molecular weight. Both wide‐angle X‐ray diffraction (XRD) and transmission electron microscopy (TEM) examinations evidenced the nanocomposite formation with exfoliated MMT homogeneously distributed in the PP matrix. A thermal stability study revealed that the nanocomposites possess good thermal stability.

X‐ray diffraction patterns of PP/IMMT (MMT = 2.2 wt.‐%) nanocomposite before and after processing.     

Ductile‐to‐Semiductile Transition in PP‐MWNT Nanocomposites

A ductile‐to‐semiductile transition in the crack resistance behaviour of PP/MWNT composites is discussed, using an essential work of fracture approach based on a post yield fracture mechanics concept and its possible interrelation to the structural attributes studied by TEM, SEM, and WAXD. A maximum in the non‐essential work of fracture is observed at 0.5 wt.‐% MWNT content, which demonstrates the enhanced resistance to crack propagation compared to pure PP, followed by a sharp decline with the increase in MWNT content to 1.5 wt.‐%, which reveals a ductile‐to‐semiductile transition. Fracture kinetic studies present a qualitative picture of the nature of such a transition in terms of a) switch over from non‐steady (in pure PP) to steady‐state crack tip opening displacement rate (in nanocomposites), and b) a ductile‐to‐semiductile transition; largely as a result of delayed‐yielding of the nanocomposites.

     

Stimuli‐responsive polymer nanocomposites based on styrene‐butadiene rubber and bacterial cellulose whiskers

Water‐induced mechanically adaptive rubber nanocomposites were prepared by mixing bacterial cellulose whiskers (BCWs) suspension with styrene‐butadiene rubber (SBR) latex, followed by evaporation method. The structure, morphology, dynamic mechanical properties, water stimuli‐responsive behavior, and biodegradability of SBR/BCWs nanocomposite films were investigated. The results showed that the hydrophilic whiskers had a significant reinforcement effect on the storage modulus of SBR matrix, which originated from the formation of a rigid three‐dimensional filler network within matrix by strong hydrogen bonding between whiskers. The SBR/BCWs nanocomposites showed pronounced water stimuli‐responsive behavior compared with neat SBR. The storage modulus of SBR/BCWs nanocomposite could be decreased by 99.2% after equilibrium water swelling. This remarkable water‐triggered modulus change is attributed to the disentanglement of BCWs network via competitive hydrogen bonding with water.     

Ductile–brittle‐transition phenomenon in polypropylene/ethylene‐propylene‐diene rubber blends obtained by dynamic packing injection molding: A new understanding of the rubber‐toughening mechanism

For a more complete understanding of the toughening mechanism of polypropylene (PP)/ethylene‐propylene‐diene rubber (EPDM) blends, dynamic packing injection molding was used to control the phase morphology and rubber particle orientation in the matrix. The relative impact strength of the blends increased at low EPDM contents, and then a definite ductile–brittle (D–B) transition was observed when the EPDM content reached 25 wt %, at which point blends should fail in the ductile mode with conventional molding. Wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to investigate the shear‐induced crystal structure, morphology, orientation, and phase separation of the blends. WAXD results showed that the observed D–B transition took place mainly for a constant crystal structure (α form). Also, no remarkable changes in the crystallinity and melting point of PP were observed by DSC. The highly oriented and elongated rubber particles were seen via SEM at high EPDM contents. Our results suggest that Wu's criterion is no longer valid when dispersed rubber particles are elongated and oriented. The possible fracture mechanism is discussed on the basis of the stress concentration in a filler‐dispersed matrix. It can be concluded that not only the interparticle distance but also the stress fields around individual particles play an important role in polymer toughening. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2086–2097, 2002     

Structural and mechanical behavior of polypropylene/ maleated styrene‐(ethylene‐co‐butylene)‐styrene/sisal fiber composites prepared by injection molding

Hybrid composites consisting of isotactic poly(propylene) (PP), sisal fiber (SF), and maleic anhydride grafted styrene‐(ethylene‐co‐butylene)‐styrene copolymer (MA‐SEBS) were prepared by melt compounding, followed by injection molding. The melt‐compounding torque behavior, thermal properties, morphology, crystal structure, and mechanical behavior of the PP/MA‐SEBS/SF composites were systematically investigated. The torque test, thermogravimetric analysis, differential scanning calorimetric, and scanning electron microscopic results all indicated that MA‐SEBS was an effective compatibilizer for the PP/SF composites, and there was a synergism between MA‐SEBS and PP/SF in the thermal stability of the PP/MA‐SEBS/SF composites. Wide‐angle X‐ray diffraction analysis indicated that the α form and β form of the PP crystals coexisted in the PP/MA‐SEBS/SF composites. With the incorporation of MA‐SEBS, the relative amount of β‐form PP crystals decreased significantly. Mechanical tests showed that the tensile strength and impact toughness of the PP/SF composites were generally improved by the incorporation of MA‐SEBS. The instrumented drop‐weight dart‐impact test was also used to examine the impact‐fracture behavior of these composites. The results revealed that the maximum impact force (F_max), impact‐fracture energy (E_T), total impact duration (t_r), crack‐initiation time (t_init), and crack‐propagation time (t_prop) of the composites all tended to increase with an increasing MA‐SEBS content. From these results, the incorporation of MA‐SEBS into PP/SF composites can retard both the crack initiation and propagation phases of the impact‐fracture process. These prolonged the crack initiation and propagation time and increased the energy consumption during impact fracture, thereby leading to toughening of PP/MA‐SEBS/SF composites. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1214–1222, 2002     

插层聚合聚丙烯-蒙脱土纳米复合材料的微观结构形态

使用偏光显微镜，扫描电镜，透射电镜和广角X射线衍射法研究了插层聚合法制备的聚丙烯－蒙脱土（PP－MMT）纳米复合材料的微观结构和形态发展。结果表明，随着插层聚合反应的进行，较大的初级MMT粒子逐渐剥离成较小的次级粒子。次级粒子由2－20片的单个MMT片层组成，其层间充满了PP分子链。提出了插层聚合过程中PP－MMT复合材料的形态发展模型。另外，MMT的加入对PP的球晶形态也有重要影响，PP完整的球晶随MMT的加入逐渐变小和趋于扭曲甚至破坏。     

Crystallization,mechanical, and fracture behaviors of spherical alumina‐filled polypropylene nanocomposites

The objectives of this paper are to study the crystallization behavior and fracture characteristics of spherical alumina (Al₂O₃) nanoparticle‐filled polypropylene (PP) composites. Nanocomposites containing 1.5–5.0 wt % of the Al₂O₃ nanoparticles (pretreated with silane coupling agent) were prepared for this investigation. Wide angle X‐ray diffraction (WAXD) results show that a small amount of β‐crystal of PP forms after adding the Al₂O₃ nanoparticles. According to differential scanning calorimetric (DSC) and optical microscopy (OM) measurements, the Al₂O₃ nanoparticles make PP spherulite size reduced and crystallization temperature of PP enhanced, by acting as effective nucleating agents. However, there are no obvious differences in the crystallinity for the virgin PP and the Al₂O₃/PP nanocomposites. Tensile test shows that both the Young's modulus and the yield strength of the Al₂O₃/PP nanocomposites increase with the particle content increasing, suggesting that the interfacial interaction between the nanoparticles and PP matrix is relatively strong. Under quasi‐static loading rate, the fracture toughness (K_IC) of the Al₂O₃/PP nanocomposites was found to be insensitive to nanoparticle content. Under impact loading rate, the Izod impact strength and the impact fracture toughness (G_c) indicate that the impact fracture toughness increases initially with the addition of 1.5 wt % of the Al₂O₃ nanofillers into the PP matrix. However, with the further addition of up to 3.0 and 5.0 wt % nanoparticles, both the Izod impact strength and impact G_c change very little. By observing the single‐edge‐double‐notch (SEDN) specimens with optical microscopy after four point bending (4PB) tests, it was found that numerous crazes and microcracks form around the subcritical crack tip, indicating that crazing and microcracking are the dominant fracture mechanisms. Scanning electron microscopy (SEM) observation confirms this result. In addition, when the strain rate of 4PB tests was increased, some wave‐like branches were formed along the fractured edge for the Al₂O₃/PP nanocomposites. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3652–3664, 2005     

Impact‐modified polypropylene/vermiculite nanocomposites

Impact‐modified polypropylene (PP)/vermiculite (VMT) nanocomposites toughened with maleated styrene–ethylene butylene–styrene (SEBS‐g‐MA) were compounded in a twin‐screw extruder and injection‐molded. VMT was treated with maleic anhydride, which acted both as a compatibilizer for the polymeric matrices and as a swelling agent for VMT in the nanocomposites. The effects of the impact modifier on the morphology and the impact, static, and dynamic mechanical properties of the PP/VMT nanocomposites were investigated. Transmission electron microscopy revealed that an exfoliated VMT silicate layer structure was formed in ternary (PP–SEBS‐g‐MA)/VMT nanocomposites. Tensile tests showed that the styrene–ethylene butylene–styrene additions improved the tensile ductility of the (PP–SEBS‐g‐MA)/VMT ternary nanocomposites at the expense of their tensile stiffness and strength. Moreover, Izod impact measurements indicated that the SEBS‐g‐MA addition led to a significant improvement in the impact strength of the nanocomposites. The SEBS‐g‐MA elastomer was found to be very effective at converting brittle PP/VMT organoclay composites into tough nanocomposites. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2332–2341, 2003     

In situ reactive compatibilization of polypropylene/epoxidized natural rubber blends by electron induced reactive processing: novel in‐line mixing technology

Blends of polypropylene (PP) and epoxidized natural rubber (ENR) were prepared by an in‐line electron induced reactive processing technique. The mixing was done in a Brabender mixing chamber coupled with an electron accelerator. The effect of sequence of electron treatment on the compatibilization of non‐polar PP and polar ENR was investigated in the presence of triallyl cyanurate (TAC). Finally, the resulting blends were characterized by different techniques, namely, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), tensile tests, and rheological studies. Generation of phase coupling and chemical compatibilization were observed from FTIR analysis. DMA studies showed enhanced high‐temperature modulus (above the glass transition temperature of both components) followed up by lowering in the tan δ peak. Rheological studies showed increase in modulus at low frequencies. Electron treatment and incorporation of rubber phase into PP showed significant effect on the degree of crystallinity of the blends, which was characterized by DSC study. The results obtained from FTIR, DMA, SEM, rheological studies, and tensile tests strongly affirmed that electron induced reactive processing of PP in presence of TAC before adding of ENR performed the best amongst all samples modified with electrons investigated in this study. Copyright © 2010 John Wiley & Sons, Ltd.