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Traditional expanded graphite (EG) films exhibit excellent electric and thermal conductivities, due to weak oxidation degree induced low defect density. However, the stiff sheet structure makes EG films very brittle, which greatly limits its applications in next generation flexible electric devices. To overcome this challenge, ammonium persulfate ((NH4)2S2O8) is employed as both expansion agent and weak oxidation agent. As a result, the weak oxidation can effectively reduce the surface energy mismatching between EG and water, making it possible for EG to be exfoliated in water by high-speed shearing combined with sonication. Most particularly, the expansion step introduces plenty of wrinkles into the EG sheets, which notably improve the flexibility of EG films. Besides, using raw graphite with large lateral size and less (NH4)2S2O8 can greatly improve the final overall performances. The prepared EG films exhibit good electric and thermal conductivities of 2977 S/cm, 854 W/mK, respectively. 33.1 dB EMI shielding property is obtained with the film thickness of only 10 μm. Moreover, 800 times direct bending can be overcome without any structure break. This facial large scale and environmentally friendly method endows the films with great potential applications in flexible electric devices.

The production of large graphene oxide (GO) sheets is often limited by the huge diffusion resistance for oxidizing agents caused by the structural uniformity of large raw graphite flakes. Previous methods often rely on the thermal or microwave, hydrogen peroxide (H2O2) expansion to overcome the large diffusion resistance. However, the pretreatment is usually energy consuming and costs extra acid which may cause more environmental risks. Here, we discovered that adding ammonium persulfate ((NH4)2S2O8) to concentrated sulfuric acid as gas expansion agent for the pretreatment of graphite flakes can lead the graphite to form a porous structure and effectively improve the specific surface area of graphite, providing more contact area for graphite with oxidizing agents due to the rapid gas release. Thus, the diffusion resistance for oxidizing agents is remarkably reduced. As a result, graphite oxide with pretreatment shows higher oxidation degree (C/O ratio: 1.7) compared with graphite oxide without pretreatment (C/O ratio: 2.3). Besides, without any exfoliation method, the as obtained uniformly oxidized graphite oxide can self-exfoliate into monolayer GO sheets with a weight average size of 1263 μm2. Moreover, the vacuum filtrated GO films exhibit superior mechanical properties (Tensile strength: 80.9 MPa).

Reactive extrusion and high-shear extrusion are both effective methods to regulate the size of dispersed phase and improve the properties for polymer blends, which have been investigated widely but separately. In this work, the combined effect of reactive and high-shear extrusion has been carried out in polylactide (PLA)/olefin block copolymer (OBC)/ethylenemethyl acrylate-glycidyl methacrylate terpolymer (EGMA) blends to better control the phase morphologies and improve the properties. It was found that, for PLA/OBC binary blends (80/20), the size of OBC dispersed phase decreased from 1.95 to 1.09 μm with increasing the rotation speed from 100 to 900 rpm, but the obtained phase morphologies couldn't be maintained after annealing treatment. In contrast, for PLA/EGMA binary blends (80/20), the effect of shear force on the dispersed phase size was negligible, due to the efficient reaction even under relative low shear force, and the morphologies of the annealed specimens is stable. For PLA/OBC/EGMA ternary blends, the suitable dispersed phase size and appropriate interfacial adhesion regulated by variations of composition and shear force lead to a significant increase of impact toughness. Super toughened PLA/OBC/EGMA blend (80/10/10–900) after annealing treatment shows impact strength of 49.61 kJ/m2, 21 times as comparing to that of the pure PLA. Our work demonstrates the importance of a suitable dispersed phase size and appropriate interfacial adhesion for the improvement of impact strength of PLA/OBC/EGMA blends achieved via a combined effect of reactive and high-shear extrusion.

High dielectric constant ceramics fillers are widely used as fillers in polymer matrix to prepare high performance dielectric composites. Homogeneous filler distribution in these composites films is found to be quite difficult to achieve balance between high dielectric constant and high breakdown strength. Herein, multilayer structured composites films containing nickelous hydroxide (Ni(OH)2) as fillers, with different multilayered structures were designed and prepared, including 2–5 layers structure with various filler distribution. The effects of multilayer structure on the dielectric performance are explored by keeping the overall filler content constant. Combined with computer simulation, it is suggested that the variation in filler distribution in these films can effectively redistribute electric field intensity. Meanwhile, the dielectric constant and breakdown strength of the overall composites can be adjusted by changing the volume ratio between high filler content layer and low filler content layer. It is noted that at least 1/3 of the overall film volume should be occupied by a high breakdown strength layer to keep rather high overall breakdown strength. Moreover, high dielectric constant layer should be the outer layers to achieve overall high dielectric constant. Among all the layered structures investigated, the maximum energy density of 6.03 J/cm3 is obtained for film with a 3-layer nonsequential arrangement structure, which is 68% higher than single layer film with identical composition. This study provides some reference value for the preparation of multilayered dielectric polymer composites films for energy storage applications.

Boron nitride nanosheets (BNNSs) are ideal candidates to endow polymers with high breakdown strength (Eb) and energy storage density (Ue). Surface modifications, including non-covalent or covalently bonding, are adopted to improve their dispersion in polymer matrix, but, usually, they suffer from inferior dielectric properties. The key is to improve their compatibility within polymer without sacrificing excellent dielectric properties, which remains to be a great challenge. In this study, three methods were designed to modify BNNSs within poly(vinylidene fluoride) (PVDF) for a comparative study. The first one involves a non-covalent polydopamine (PDA) coating (PDA-BNNSs); the crystal lattice was well-preserved, but additional PDA was introduced. The second method involves basal hydroxylation via nitric acid (HNO3) oxidation (BOH-BNNSs) with hydroxyl groups (–OH) mainly located at the basal plane, thus, seriously damaging the in-plane crystal. The third one is edge-hydroxylation via ball-milling (EOH-BNNSs) with –OH groups being regulated at the boundary; thus, integrated basal crystal is largely maintained. It was very interesting to find that the dispersion, interfacial interaction and orientation of BNNSs in PVDF matrix are more or less similar for all three surface-modification methods, but the enhancement of Eb is very different. PDA-BNNS and BOH-BNNS filled PVDF nanocomposites exhibited a limited enhancement of Eb, while a greatly improved Eb (∼146.6%) was observed for EOH-BNNS filled PVDF nanocomposites in comparison with that of PVDF/BNNSs nanocomposites. Therefore, edge-hydroxylation could endow PVDF/EOH-BNNS nanocomposites with impressive Eb (585 kV mm−1) and Ue (16.23 J cm−3). Because the low Eb of PDA and the decreased band gap energy (Eg) of BOH-BNNSs (2.73 eV) are both disadvantages for achievement of high Eb. Inversely, well-preserved basal crystal lattices could be obtained if –OH groups are regulated at the boundary, which makes EOH-BNNSs not only display better dispersion and interfacial interaction but also retain higher Eg (5.76 eV). This study demonstrates the importance of maintaining an integrated crystal lattice of BNNSs when exposed to surface modification for the first time. Our study provides guidance for surface-modification of BNNSs and preparation of polymer-based capacitors with excellent performance.

Phase change materials (PCMs), as promising energy saving and heat-dissipation materials, have the advantage of a high latent heat in the phase transition process, and thus have huge potential applications in electronic devices, powerful batteries and modern buildings. The aspirational target is to achieve excellent thermal conductivity (TC) and extraordinary shape stability in PCMs, while simultaneously maintaining their high latent heat. In this study, an anisotropic and robust three-dimensional interconnected cellulose/boron nitride nanosheet (BNNS) skeleton was designed within polyethylene glycol (PEG) composites via the self-assembly of concentrated cellulose/BNNS aqueous mixtures followed by vacuum impregnation and cold compressing. By virtue of this typical structure, the PEG composites could take full advantage of the high in-plane TC of the BNNSs due to their efficient orientation during the cold compressing process and immensely diminish the phonon scattering among the BNNS pathways due to the overlapping BNNS contact. In addition, a robust cellulose/BNNSs scaffold with impressive compressive strength (3.03 MPa) similar to reinforced concrete was obtained, which benefitted from the cooperative reinforcement of the cellulose nanofibers and high-strength BNNSs and could also avoid any shape change when vacuum-impregnated with PEG. As a result, the in-plane TC of the PEG composites reached as high as 4.764 W m−1 K−1 at only 10 vol% loading, which is almost 1400% of that of pure PEG. Furthermore, the PEG composites could also maintain their original shape at a high temperature (101 °C), even when loaded with a weight of 500 g, which is almost 500 times heavier than their own weight. Besides, the PEG composites with a relatively small loading of BNNSs could also maintain a high-level of latent heat (136.8 J g−1). All these excellent comprehensive properties guarantee them a bright future in applications such as energy conversion and storage systems and electrical insulating materials for thermal management.

Chemical modification of boron nitride nanosheets (BNNSs) is a simple but effective method to improve their dispersion and compatibility within polymer nanocomposites. The key point is how to import compatible functional groups but simultaneously retain the intact crystal lattice. In this study, two different hydroxylation methods, namely nitric acid oxidation and aqueous ball milling, were adopted for surface modification of BNNSs. And a comparative study was carried out in terms of hydroxyl (OH) content, position of modification and the thermal conductivity (TC) after mixing them with a biodegradable cellulose nanofiber (CNF). TEM mapping, XRD and HRTEM indicated that nitric acid oxidation mainly resulted in an in-plane hydroxylation of BNNSs (POH-BNNSs) whose crystal lattice was seriously damaged, while aqueous ball milling led to most likely an edge hydroxylation of BNNSs (EOH-BNNSs) whose crystal lattice could be well preserved. As a result, strikingly, the TC of POH-BNNS filled nanocomposites only showed a little growth (10.2%) at a low OH content or even decreased at a higher OH loading, while an impressive thermal enhancement of almost 100% was achieved for CNF/EOH-BNNS nanocomposites. Such a substantial improvement signifies the critical role of edge-hydroxylation, which can simultaneously reduce interfacial thermal resistance and retain the intact basal crystal lattice to facilitate acoustic phonon transfer. This research provides deep insight into modification of two-dimensional nanomaterials from the point of view of the defect position, and an edge-selective modification strategy is expected to be of great advantage for the fabrication of highly thermally conductive nanocomposites.

Various functions of polymer composites, including electrical conductive, thermal conductive, dielectric, EMI shielding, strain sensing, etc, has been extensively investigated. These functions need to be delivered by functional filler or structure. Therefore, the morphological control of these functional filler or structure should play vital role on the final properties of these functional polymer composites. In recent years, we have carried out a series of studies focusing on “The relationship between different morphological control methods--filler network morphology & property—functionality”. Efforts have been made on investigating various morphology control methods including: construction and destruction of filler network during processing, multi-layered structure through high speed thin-wall injection molding and macroscopic segregated network structure. Herein, the formation of multi-layered structure during high speed thin-wall injection molding process will be introduced. The thermodynamic and kinetic issues influencing the formation of such structure and the application of such structure for the preparation of functional polymer composites will be systematically discussed.Various functions of polymer composites, including electrical conductive, thermal conductive, dielectric, EMI shielding, strain sensing, etc, has been extensively investigated. These functions need to be delivered by functional filler or structure. Therefore, the morphological control of these functional filler or structure should play vital role on the final properties of these functional polymer composites. In recent years, we have carried out a series of studies focusing on “The relationship between different morphological control methods--filler network morphology & property—functionality”. Efforts have been made on investigating various morphology control methods including: construction and destruction of filler network during processing, multi-layered structure through high speed thin-wall injection molding and macroscopic segregated network structure. Herein, the formation of multi-layered structure during high speed thin-wall injection molding process will be introduced. The thermodynamic and kine...

Two-dimensional (2D) nanomaterials have been widely used as advanced functional materials due to their special nanostructures and various functionalities. Researchers working on 2D nanomaterials are facing several problems, the difficulties in synthesis, scarcity of species, largely unclear formation mechanism and non-universal preparation method. Herein, this paper reports a new method based on electrospinning to fabricate 2D inorganic materials (titanium dioxide) with thickness around 20 nm and width/thickness ratio of >50. These 2D nanobelts TiO2 could enhance the dielectric performance of PVDF based composites much more significantly, and the energy density of 12.45 J/cm3 could be easily achieved with a small volume fraction (3 vol%) of the nanobelts. Such method has many advantages such as safe production, low production cost, and continuous production. More importantly, this approach is potential to become a universal method to fabricate a range of 2D inorganic nanomaterials in the future due to its universality.

Graphene nanosheet (GNS) films exhibit good thermal and electric conductivities due to low oxygen content and defect density. However, the weak interlayer interaction forces have resulted in poor mechanical properties and flexibility for GNS films. In order to meet this challenge, aramid nanofiber (ANF) is introduced into the GNS films by solution mixing, then a small amount of water is added to adjust the aramid nanofiber framework (ANFF) in the solution. The results indicate that adding a small amount of water into the aramid nanofiber/dimethyl sulphoxide (ANF/DMSO) suspension can recover the hydrogen bonds between ANF, promoting the ANF to form a stable framework. This design strategy leads to a delectate balance between flexibility and electric, thermal conductivities. With the improvement of water or ANFF content, the mechanical properties of GNS/ANFF composite films are gradually increased. And the electric and thermal conductivities are not influenced by the water content but decrease with the increasement of ANFF content. Most importantly, the flexibility of GNS films is greatly improved with little sacrifice of electric and thermal conductivities by adding only 2 wt% ANFF (GNS-2). The tensile toughness of GNS-2 composite films is dramatically improved from 30.8 to 108.7 kJ m−3, while the electric and thermal conductivities of GNS films are slightly dropped from 827 to 569 S cm−1 and from 140 to 131 W m−1 K−1, respectively. Moreover, the excellent flexibility of the composite films can be maintained even after 1000 times of direct bending. The good over-all properties together with its easy preparation process endows GNS/ANFF composite films with potential applications in next-generation flexible electric devices.

Rapid development of artificial intelligence and wearable electronics facilitate the demand for high performance piezoresistive sensors. Not only high sensitivity but also good mechanical property as well as long-term usage are critical parameters to value piezoresistive sensors performance. In this work, a flexible, highly sensitive and versatile piezoresistive sensor with 3D porous structures, based on commercially available polyurethane (PU) foams coated with cellulose nanofiber @ carbon black (CNF@CB) conductive layer, was fabricated. We are particularly interested in the effect of interaction between the conductive filler and PU foam on the sensor performance. Thus, low-pressure oxygen plasma treatment was innovatively adopted to modify and activate PU scaffold to enhance the affinity between PU framework and CNF@CB conductive layer. Strong interfacial interaction is not only contributed to the sensitivity but also to the mechanical reinforcement of conductive foams, which is helpful to the long-term usage. The as-prepared PU/CNF@CB conductive foams exhibit very high compressive sensitivity of 0.35 kPa−1 (about 100% increase compared with the untreated ones), along with good mechanical property (29 kPa at 50% compressive strain, about 27% increase compared with the untreated ones) and electrical property (0.047 S/m). In addition, good stability and durability are demonstrated for the prepared PU/CNF@CB conductive foams especially under micro-pressure or micro-strain which is a huge challenge for bulk piezoresistive sensors. Such a kind of sensitive material combined with low-cost, flexibility, high sensitivity, duration, is very attractive in high-tech area.

The effect of conductive network morphology and interfacial interaction on the strain sensing capability of conductive polymer composites (CPCs) is thought as crucial. Nevertheless, the stability in strain sensing behavior has barely been investigated. Herein, the resistivity–strain behavior in terms of stability and sensitivity of CPCs based on poly(styrene-butadiene-styrene) (SBS) containing multiwalled carbon nanotubes (MWCNTs) are studied. It is shown that the preparation method has an important influence on the resistivity–strain behavior of these CPCs. The sensitivity increases with decreasing filler content for both composites under linear uniaxial strain, showing higher strain sensitivity near the percolation threshold. A higher and wider range of sensitivities is obtained for melt mixed SBS/MWCNT. Meanwhile, resistivity downward drifting and shoulder peaks are shown for composites from melt mixing under dynamic strain. Interestingly, linear relationships and reversible resistivity in every cycle are observed for composites from solution mixing, showing good electromechanical consistency, stability and durability. From the TEM, rheology, SEM, SAXS, Raman microscopy and analytical modeling studies, the difference in morphology is thought to be responsible for such resistivity–strain behavior. As more disordered and less densely packed conductive networks in melt mixed CPCs are more easily destroyed under strain, evenly distributed and densely packed networks in solution mixed CPCs are more stable during cyclic stretching. Finally, different human motions have been detected using these CPCs, demonstrating the potential application of these CPCs as movement sensors.

Three types of high-density polyethylene (HDPE) with different molecular weights (high, medium and low) were adopted to evaluate the influence of matrix molecular weight on the structure-property relation of injection-molded HDPE/mica composites through a combination of SEM, 2d-WAXS, DSC, DMA and tensile testing. Various structural factors including orientation, filler dispersion, interfacial interaction between HDPE and mica, etc., which can impact the macroscopic mechanics, were compared in detail among the three HDPE/mica composites. The transcrystallization of HDPE on the mica surface was observed and it exhibited strong matrix molecular weight dependence. Obvious transcrystalline structure was found in the composite with low molecular weight HDPE, whereas it was hard to be detected in the composites with increased HDPE molecular weight. The best reinforcement effect in the composite with low molecular weight HDPE can be understood as mainly due to substantially improved interfacial adhesion between matrix and mica filler, which arises from the transcrystallization mechanism.

Self-assembly of block copolymer is an effective strategy to prepare periodic structures at nanoscale. In this paper an unique and very simple method to prepare inorganic silica nanopattern is demonstrated from self-assembling of poly(styrene-block-dimethylsiloxane) (PS-b-PDMS) on the surface of silicon wafer. To simplify the patterning process, at first we obtain highly ordered PDMS microdomains, which are covered with PS layer by controlling solvent vapor annealing conditions. Following exposure to UV/O3 irradiation, nanopatterned surface consisting of silicon oxide is fabricated directly via selectively etching PS phase and converting PDMS phase into silicon oxide. As tuning the composition of the block copolymer, hexagonally packing dot and straight stripe pattern can be obtained. Finally, the time evolution from spheres morphology to aligned long cylinders is discussed. These results hold promise for nanolithography and the fabrication of nanodevices.

A relatively high predetermined crystallization temperature (135°C) was chosen to grow well developed iPP spherulites, then the partial melting was carried out at a temperature of 165°C, where the preformed spherulites were seen to only decrease their size but not completely melted. The crystallization behavior of partially melted isotactic polypropylene (iPP) has been carefully examined by different scanning calorimetry (DSC) and polarized light microscopy (PLM). The experimental results show that at a special annealing temperature (165°C) the melting behavior of iPP includes two parts with different mechanism, one part is the melting of iPP spherulite outside, another is the partial lamellae perfection during longer annealing time in the unmelted spherulite. The conformational orders of the iPP melt decrease with the increase of the annealing temperature.

The electrical conductivity and impact strength of polypropylene(PP)/EPDM/carbon black ternary composites were investigated in this paper. Two processing methods were employed to prepare these ternary composites. One was called one-step processing method, in which the elastomer and the filler directly melt blended with PP matrix. Another one was called two-step processing method, in which the elastomer and the filler were mixed first, and then melt blended with pure PP. To get an optimal phase morphology that favors the electrical conductivity and impact strength, controlling the distribution of CB in PP/EPDM blend was a crucial factor. Thus the interfacial tension and the work of adhesion were first calculated based on the measurement of contact angle, and the results showed that CB tended to be accumulated around EPDM phases to form filler-network structure. Expectably, the filler-network structure was observed in PP/EPDM/CB(80/20/3) composite prepared by two-step processing method. The formation of this filler-network structure decreased the percolation threshold of CB particles in polymer matrix, and the electrical conductivity as well as Izod impact strength of the composite increased dramatically. This work provided a new way to prepare polymer composites with both improved conductivity and impact strength. Copyright © 2009 John Wiley & Sons, Ltd.

The formation of a nanohybrid shish-kebab (NHSK) superstructure, in which fibrillous carbon nanotubes (CNTs) act as shish while polymer lamellae act as kebab, is a novel way to bond the polymer and CNTs together and was first observed in the solution crystallization of polyethylene in the presence of CNTs. In this work, a direct formation of nanohybrid shish-kebab in the injection molded bar of high-density polyethylene (HDPE)/multiwalled carbon nanotubes (MWCNTs) composite, has been achieved, via a so-called dynamic packing injection molding technology (DPIM), in which oscillatory shear field was imposed on the gradually cooled melt during the packing solidification stage. Interestingly, whatever the long axis of CNTs is perpendicular to or parallel to the shear flow direction, the lamellae of PE is always perpendicular to long axis of CNTs. The three-step mechanism, including (1) the disentanglement and orientation of both PE and CNTs, (2) PE folded-chain lamellae directly nucleated on CNTs surface and/...

The polymer matrix structure and the interface are strongly influenced by filler in semi-crystalline polymer composites because the fillers have the potential to nucleate the polymer crystallization. The structure of the nucleated crystalline polymer on filler is of particular interest and is a key to the interfacial enhancement. In this work, whiskers, with a large length/diameter ratio and with a diameter (0.2–2 μm) much larger than that of carbon nanotubes but much smaller than that of common fibers, were used to nucleate crystal morphology in polypropylene (PP)/whisker composites. The crystal morphology, interfacial adhesion and tensile properties of the composites were carefully investigated. A kind of peculiar shish–calabash crystallization morphology, with whisker serves as shish and PP spherulites serves as calabash, was observed for the first time in the thin film via PLM and in the injection molded bars by SEM. The formation mechanism of this shish–calabash structure was attributed to be that only a few nuclei could be induced on the whisker surface, which develop into large PP spherulites without hindrance, and finally stringed by the whisker, forming the shish–calabash structure. As a result, a significant improvement of interfacial interaction and tensile properties has been achieved.

Molten polymers are usually exposed to varying levels of shear flow and temperature gradient in most processing operations. Many studies have revealed that the crystallization and morphology are significantly affected under shear. A so-called “skin-core” structure is usually formed in injection-molded semicrystalline polymers such as isotactic polypropylene (iPP) or polyethylene (PE). In addition, the presence of nucleating agent has great effect on the multilayered structure formed during injection molding. To further understand the morphological development in injection-molded products with nucleating agent, iPP with and without dibenzylidene sorbitol (DBS) were molded via both dynamic packing injection molding (DPIM) and conventional injection molding. The structure of these injection-molded bars was investigated layer by layer via SEM, DSC, and 2 days-WAXD. The results indicated that the addition of DBS had similar effect on the crystal size and its distribution as shear, although the later decreased the crystal size more obviously. The combination of shear and DBS lead to the formation of smaller spherulites with more uniform size distribution in the injection-molded bars of iPP. A high value of c-axis orientation degree in the whole range from the skin to the area near the core center was obtained in the samples molded via DPIM with or without DBS, while in samples obtained via conventional injection molding, the orientation degree decreased gradually from the skin to the core and the decreasing trend became more obvious as the concentration of DBS increased. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Dibenzylidene sorbitol (DBS) exists in the form of fibril and usually acts as an effective nucleating agent to facilitate crystallization of polyolefin during manufacturing. In this research, the isothermal crystallization of isotactic polypropylene (iPP) containing different amounts of DBS was followed by dynamic rheometry, and described upon a viewpoint of viscoelastic property evolution. Since the adopted temperatures within the entire sample preparation and characterization process were below the melting point of DBS, the DBS additives played a role of only solid nucleating agent, thus the possible effect of a changed miscibility between iPP and DBS on the viscoelastic properties as change of temperature could be ignored. Although saturation of nucleating iPP was observed at 0.1% DBS concentration, a negative influence with further increasing DBS content on the crystallization of iPP was determined for the first time via time sweep of G ′ upon a single angular frequency and application of “inverse quenching” protocol within a wide range of angular frequency. Even more, a largely increased G ′ and viscosity were observed in the melt as decreasing the temperature of iPP containing 0.1% DBS, suggesting a strong quasi-solid like behavior before iPP crystallization. A complement for well understanding the crystallization of iPP containing nucleating agent was discussed based on the formation of the DBS fibrils' network, the interfacial tension between crystalline/amorphous phase, and the consistency of crystallizing lamellae. Our study demonstrates clearly that the crystalline characteristic upon saturation of heterogeneous nucleating is difficult to be detected by traditional means, but could be followed reasonably by rheological measurements which is much sensitive to the microstructural changes.

In this work, raw multiwalled carbon nanotubes (MWNTs) without any pre-treatment were blended with linear low density polyethylene (LLDPE), then molded via a so-called Dynamic Packing Injection Molding (DPIM) technique, in which oscillatory shear was exerted on the prepared composites during the stage of cooling solidification. The injection molded samples were extracted by xylene to remove LLDPE, and the remained MWNTs were collected and characterized. Shear enhanced interfacial adhesion between MWNTs and LLDPE was confirmed by dissolution experiment and Fourier transform infrared. The former a longer mixing time in xylene for remained MWNTs compared with raw MWNTs, while in the latter an increased intensity of characteristic LLDPE peak for MWNTs subjected to dynamic packing injection molding. More importantly, SEM images showed a formation of MWNTs/LLDPE nanohybrid shish–kebab, in which MWNTs served as shish, and LLDPE lamellae as kebab and periodically decorated on MWNTs. A simultaneously improved tensile strength and elongation of LLDPE have been achieved by adding the LLDPE-decorated MWNTs. Our work provides a new way for the modification of MWNTs, particularly a convenient way for the enhancement of interfacial adhesion in polymer/MWNT composites via realistic molding processing.

In this paper, the structural orientation and tensile properties were investigated on the extrusion-elongated sheets of polypropylene (PP)/multi-walled carbon nanotubes' (MWCNTs) composites. The MWCNTs were modified via reactive grafting with octadecylamine to enhance the capability of dispersion in PP matrix. The orientation level of composite sheets was adjusted through adopting various drawn speeds after extrusion, and the structure–property relation was inspected systematically through the combination of two-dimensional wide-angle X-ray scattering, polarized light microscopy and tensile mechanical testing. The tensile behavior of the extrusion-drawn sheet was significantly impacted by both adding MWCNTs and increase of drawn speed. An optimization for simultaneously strengthening and toughening was achieved in the sample with relatively high content MWCNTs prepared upon fast drawn speed. Incorporation of nanotubes didn't alter the orientation degree of crystalline lamellae obviously, but the oriented nanotubes could act as the nucleating templates for the growth of oriented crystalline superstructure. Combined with the present morphological characterizations and the results in other published papers, it was postulated that the oriented superstructure of cylindrulites composed of rigid CNTs as nucleus and PP lamellae as kebabs might be generated in the extrusion-elongated sheets of PP/MWCNTs, which was regarded as the morphological reason for a reinforcing effect on tensile performances.

In this research, a linear low density polyethylene (LLDPE) was first melt blended with a series of high density polyethylenes (HDPE) with different molecular weights at a fixed ratio of LLDPE/HDPE = 90/10 (w/w). The prepared HDPE/LLDPE blends were then injection-molded into specimen bars through a dynamic packing injection molding (DPIM) technique, in which an oscillating shear field was imposed on the melt by two pistons that move reversibly with the same frequency during the packing stage. The crystal morphology, orientation and tensile properties were characterized by scanning electron microscopy, two-dimensional wide-angle X-ray scattering and Instron, respectively. Compared with conventional injection molding, DPIM caused an obvious increase in tensile strength in the injection-molded bars. Interestingly, LLDPE blended with low molecular weight HDPE (LMW-PE) was found to possess much higher tensile strength than that blended with high molecular weight HDPE (HMW-PE). Shish–kebab morphology was observed for all blends obtained, regardless of the molecular weight of the HDPE. However, thicker but shorter lamellae were observed for the LLDPE/LMW-PE blend, corresponding to a higher melting temperature; while thinner but longer lamellae were seen for the LLDPE/HMW-PE blend, corresponding to a lower melting temperature. Furthermore, the phase miscibility between HDPE and LLDPE was found to increase with increasing HDPE molecular weight, which would affect the sensitivity of molecular chains for response to external shear. The changed miscibility, together with the changed entanglement density in different HDPE was responsible for the change in tensile strength and unique crystal morphology of LLDPE induced by adding HDPE.

Background: Poly(ethylene terephthalate) (PET)/polyamide-6 (PA-6) blends are promising for engineering and food-packaging applications. However, their poor toughness limits their use. In this study, an ethylene–acrylate–(maleic anhydride) terpolymer (E-AE-MA) was added to PET/PA-6 blends in order to improve the toughness. Results: Izod impact tests indicated an excellent toughening effect of E-AE-MA. E-AE-MA particles were observed to be selectively dispersed at the interface between PET and PA-6 phases and in the domain of the PA-6 phase. Fourier transform infrared spectroscopy and differential scanning calorimetry results demonstrated that the formation of E-AE-MA layers around PA-6 particles cut off the interaction between PET and PA-6, resulting in an enlarged PA-6 phase domain. Conclusion: Based on the experimental results, a core–shell microstructure, with PA-6 as a hard core and E-AE-MA as a soft shell, could be suggested. The formation of this core–shell microstructure, along with the increased PA-6 phase domain size, is the main toughening mechanism of E-AE-MA in PET/PA-6 blends. Copyright © 2007 Society of Chemical Industry

In this work, halloysite nanotubes (HNTs), a new type of inexpensive filler, were used for the modification of polypropylene (PP). HNTs were first surface treated by methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium, then melt mixed with PP. Scanning electron microscope (SEM) was used to examine the dispersion of HNTs in PP matrix. Differential scanning calorimetry (DSC), polarized light microscope (PLM), dynamic melt rheometry and wide angle X-ray diffraction (WAXD) were employed to investigate the crystallization behavior of the prepared PP/HNT composites. The mechanical properties were evaluated by Instron and impact tests. SEM results revealed that HNTs could be well-dispersed in PP matrix and had a good interfacial interaction with PP, even up to a high content of 10 wt%. DSC data indicated that HNTs could serve as a nucleation agent, resulting in an enhancement of the overall crystallization rate and the non-isothermal crystallization temperature of PP. PLM showed a constant spherulite growth rate and a decreased spherulite size at given isothermal crystallization temperature, suggesting that nucleation and growth of a spherulite are two independent processes. The result obtained by dynamic melt rheometry indicated that HNTs mainly promoted nucleation and had not much influence on the growth of PP crystallization. Nevertheless, by fast cooling the samples, almost constant spherulite size can be obtained for both pure PP and PP/HNT composites due to the limited nucleation effect of HNTs on PP crystallization. WAXD showed that HNTs mainly facilitated α-crystal form of PP. Though a good dispersion of HNTs in PP matrix was observed, out of our expectation, not much enhancement on mechanical properties of PP/HNT composites had been achieved, and this could be mainly ascribed to the constant crystallinity and spherulite size of PP as well as the small length/diameter ratio of HNTs.

Multi-wall carbon nanotubes (MWNTs) grafted with alkyl chain were used for reinforcement of polypropylene (PP). For achieving excellent tensile properties, the as-prepared PP/MWNTs composites were subjected to a unique injection molding, as so-called dynamic packing injection molding, to induce a highly oriented structure with both PP chains and MWNTs aligned along the shear flow direction. Not only Young's modulus and tensile strength were enhanced, as expected for oriented materials, but also more importantly composites containing only 0.1–0.3 wt% MWNTs were much ductile compared with the polymer matrix. The addition of PP- g -MMA made a drop in the elongation at break to only 15%; however, it could be improved to 80–100% after incorporation of small amount of MWNTs. This improvement in ductility could be ascribed to: (1) the increased mobility of both the PP chains and MWNTs, as they are oriented along tensile deformation direction and (2) the bridging effect of the oriented MWNTs on the crack development during tensile failure.

As a continuation of our previous works on exploring shear-induced epitaxial crystallization of polyolefin blends during practical molding processing [Na et al. Polymer 2005; 46, 819 and 5258], the present study focused on the importance of molecular weight on the formation of epitaxial structure in injection-molded bars of high-density polyethylene (HDPE)/isotactic polypropylene (iPP) blends. By choosing two kinds of HDPE and two kinds of iPP with high molecular weight or low molecular weight, four blends with different molecular weight combinations can be designed. After making the blends via melt mixing, the injection-molded bars were prepared in a so-called dynamic packing injection molding equipment where repeated shearing was imposed on the melts during the solidification stage. Crystal structure and orientation were estimated mainly through 2D-WAXD. Our results indicated that an appropriate matching of low molecular weight HDPE and high molecular weight iPP was more favorable for epitaxial crystallization than other component matches. The effects of orientation and epitaxy on the re-crystallization behaviors of polyolefin blends have been elucidated in detail through PLM experiments. Moreover, epitaxy has been proved to play a positive effect in determining the ultimate mechanical properties of injection-molded bars.

A novel experimental technique to follow the crystallization processes of poly(propylene)/ MWCNT composites that experience a steady shear deformation using dynamic melt rheometry is described. The effects of heterogeneous nucleation, temperature, and preshear on the crystallization behaviors were determined. A quantitative evaluation of crystallization kinetics difference between quiescent and preshear conditions could be achieved. By combining rheology with POM, we demonstrate that two different crystallization processes account for the shear-enhanced crystallization at low and high temperatures, respectively.

Three isotactic polypropylene(iPP)/organoclay nanocomposites with changed basal resin polarity and molecular weight but fixed clay content (10 wt.%) were prepared through melt-blending. To correlate the rheological properties with the orientation behavior and tensile property in injection-molded bars, the shear response and disorientation kinetics of those molten composites were investigated through large-amplitude oscillatory shear measurements and stress relaxation experiments, respectively. Then, dynamic packing injection molding was carried out to exert oscillatory shear on the molten composites during the solidification stage, for preparation of composites with high-level orientation. The orientated structures of injection-molded bars were inspected through 2-D wide-angle X-ray scattering analysis. Our results indicated for the first time that the rheological behaviors, such as alignment induced by large-amplitude shear and stress relaxation, would be the reliable references for estimating the orientation capability of nanocomposites in practical injection-molded processing. The rheological response to shear and the disorientation kinetics play crucial roles in determining the orientation and tensile strength of molded composites.

In this study, both organoclay and EPDM- g -MA rubber were used to simultaneously improve the toughness and stiffness of polyamide 6 (PA6). We first prepared PA6/EPDM- g -MA/organoclay ternary nanocomposites using melt blending. Then the composites were subjected to traditional injection molding and so-called dynamic packing injection molding. The dispersion of clay, phase morphology, crystallinity and orientation of PA6 as well the mechanical properties were characterized by WAXD, SEM, DSC, 2D-WAXS and mechanical testing, respectively. The effects of clay on phase morphology and mechanical properties of PA6/EPDM- g -MA blends could be summarized as follows: (1) weakening interphase adhesion between PA6 and EPDM- g -MA rubber particles, resulted in increasing of rubber particle size, as the clay and rubber contents are low; (2) preventing coalescence of rubber domains, arisen in decreasing of rubber particle size, as the clay and rubber contents are high; (3) the blocking effect on the overlap of stress volume around rubber particles caused broadening of the brittle–ductile transition region and decrease of toughness, and (4) the effective stress transfer leading a better reinforcement when the interparticle distance is smaller than the critical value.

In this article, the phase morphology and mechanical properties of polypropylene (PP)/ethylene–octane copolymer (POE) blends with fixed ratio (60/40) obtained via different processing conditions, including barrel temperature, injection speed, and mold temperature, have been investigated. SEM was carried out for detailed characterization of phase morphology from the skin to the core, layer by layer. It was interesting that for all the processing conditions no dispersed POE elastomer was observed in the skin layer but elongated POE particles with large size were observed in the subskin layer. From the transition zone to the core layer, an increased phase separation was observed, which could lead to a formation of cocontinuous morphology, depending on the processing condition used. Higher barrel temperature, lower mold temperature, and higher injection speed could result in a smaller size of POE phase. The tensile strength and impact strength were found not sensitive to barrel temperature and mold temperature but to the low injection speed, both tensile strength and impact strength had a higher value for specimen obtained via low injection speed. The formation of the skin-core morphology and the effect of processing conditions on the phase morphology were discussed based on crystallization kinetics of PP matrix, rheology, and shear induced phase mixing. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

In this article, polypropylene (PP)/multiwall carbon nanotubes (MWNTs) composites were prepared through dynamic packing injection molding, in which the oscillatory shear was exerted on the molten composite during packing and solidification stage of injection-molding. A simultaneous increase of tensile strength and impact strength has been achieved for PP/MWNTs composites containing only 0.6 wt % MWNTs. Particularly, the impact strength was found increased by almost 50% at such low MWNTs content. These improvements in properties were attributed to uniform dispersion and possible orientation of nanotube induced by shear stress. It was suggested that the dynamic packing injection molding could provide much strong shear force for better dispersion of MWNTs in PP matrix, on one hand, but breakdown the aspect ratio of MWNTs, on the other. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1880–1886, 2007

The transcrystal plays an important role in the enhancement of mechanical and thermal performances for polymer/glass fiber composites. Shear has been found to be a very effective way for the formation of transcrystal. Our purpose of this study was to explore the possibility to obtain the transcrystal in real processing such as injection molding. We will report our recent efforts on exploring the development of microstructure of polypropylene (PP)/glass fiber composite from skin to core in the injection-molded bars obtained by so-called dynamic packing injection molding which imposed oscillatory shear on the melt during solidification stage. A clear-cut shear-facilitated transcrystallization of PP on glass fibers was observed in the injection-molding bar for the first time. We suggested that shear could facilitate the transcrystalline growth through significantly improving the fiber orientation and the interfacial adhesion between fiber and matrix.

The phase behavior of polymer blends under the effect of shear has been a subject of considerable interest from the viewpoint of both theoretical research and industrial application, because the shear stress is unavoidable during processing. In this work, we reported the change of phase behavior and mechanical properties of Polystyrene (PS)/Styrene-ethylene-butylene-styrene (SEBS) blends achieved via a shear-assistant injection molding, which was called dynamic packing injection molding (DPIM). The size of dispersed SEBS particles in PS matrix was found to be increased for the samples obtained by dynamic packing injection molding (DPIM), compared with those obtained by conventional molding, indicating a shear induced phase coarsening. The shear induced phase coarsening can be further demonstrated by the decrease of impact strength of dynamic packing injection molded samples. However, the shear-induced phase coarsening will be eliminated after annealing the samples at high temperature for certain time. The particle size, which related to the capability to deform under the effect of shear, was found to play an important role to determine the phase morphology. Our result suggested that shear stress induced phase coarsening was a process of not only molecular configuration change but also deformation change under shear.

In this article, the injection-molded bars of isotactic polypropylene/organoclay nanocomposite with different clay contents have been obtained via dynamic packing injection molding (DPIM). The oriented microstructure including layered nanoparticles and PP lamellae has been inspected through 2D-WAXS analyses along the sample thickness of the molded bars. Depending on the clay content and sample thickness, various oriented clay structures with nanoparticles uniplanar-axially oriented parallel to the surface of molded bar, or partially tumbled around the flow axis of the molded bar, or even a random orientation, could be observed. The observed orientation behavior of nanoparticles could be temporarily elucidated as the results of the sensitive response of layered nanoparticles to shear deformation and the structural recovery of clay network assisted by the electrostatic attraction existing between adjacent nanoplatelets.

The evaluation of microstructure and crystal morphology in injected-molded bar becomes much complicated because of the existence of a shear gradient and a temperature gradient from the skin to the core of the samples. To understand the relationship between shear rate-molecular weight and oriented structure of injection molded bar, in this work, the hierarchy structure and the effect of molecular weight on the formation of shish-kebab structure were investigated by examining the lamellar structure of injection molded samples of high density polyethylene (HDPE) with different melt flow index (MFI), layer by layer, along the sample thickness. To enhance the shear effect, so-called dynamic packing injection molding (DPIM), in which the melt is firstly injected into the mold and then forced to move repeatedly in a chamber by two pistons that move reversibly with the same frequency as the solidification progressively occurs from the mold wall to the molding core part, was used to obtain the molded bar. Furthermore, a small amount of ultra-high molecular weight polyethylene (UHMWPE) was added into HDPE to explore the effect of UHMWPE on the crystal morphology and orientation. Our results indicated (1) that the overall orientation in the molded bar increased with decreased MFI, and a small amount of UHMWPE could enhance substantially HDPE orientation; (2) at the skin, there existed intertwined lamellae constituting an interlocked lamellar assembly, a typical shish-kebab structure gradually developed from the subskin-layer to the core, with increased shish content toward the center, but in the core was a spherulite-like superstructure with randomly distributed lamellae; (3) UHMWPE played an important role not only in the formation of shish, but also in the transformation from spherulite to shish-kebab oriented structure for HDPE with a low molecular weight (high MFI).

In order to achieve better mechanical properties, most work on polymer/fiber composites has been focused on the importance of the chemistry used to modify the surface of the fibers and improving the adhesion between the fiber and the matrix using coupling agents. Our purpose in this study was to determine the effect of shear on the fiber orientation and interfacial adhesion in poly(propylene)/glass fiber composites via dynamic packing injection molding (DPIM), in which the melt is first injected into the mold and then forced to move repeatedly in a chamber by two pistons that move reversibly with the same frequency as the solidification progressively occurs from the mold wall to the molding core part. SEM, TGA, FT-IR, AFM and mechanical testing were used to characterize the samples obtained. The majority of fibers are aligned parallel to the flow direction along the sample thickness, even at the core, in contrast to the products obtained via conventional injection molding where the orientation of fibers is observed only at the skin. More importantly, we found that shear could enhance not only the fiber orientation, but also the interfacial adhesion between the fibers and the matrix, particularly for samples with higher fiber contents, resulting in an obvious increase in tensile strength and the onset degradation temperature. A possible transcrystallization was evidenced by AFM investigations of the dynamic packing injection molded samples, which is worth further study.

In this paper, EPDM rubber and nano-SiO2 particles were employed to modify PP simultaneously. Our goal was to control the distribution and dispersion of EPDM and nano-SiO2 particles in PP matrix by using an appropriate processing method and adjusting the wettability of nano-SiO2 particles toward PP and EPDM, so as to achieve a simultaneous enhancement of toughness and modulus of PP. With regard to this, two kinds of nano-SiO2 particles (with hydrophilic or hydrophobic) as well as two processing methods (one-step or two-step) were employed to prepare PP/EPDM/SiO2 ternary composites. A unique structure with the majority of EPDM particles surrounded by SiO2 particles was first observed by using hydrophilic SiO2 and two-step processing method, resulting in a dramatically increase of Izod impact strength as the rubber content in the range of brittle–ductile transition (15–20 wt%). The observation that poor adhesion and poor compatibility between particles and PP matrix could result in a significant increase in Izod impact strength was unusual and needed further investigation. This could be tentatively understood as a consequence of the overlap of the ‘stress volume’ between EPDM and SiO2 particles due to the formation of the unique structure. Our work provided a deep understanding of the toughening mechanism and a new way for the preparation of high performance polymer composites.

In this communication, we will demonstrate, by using poly(p-phenylene sulfide) (PPS)/polyamide66 (PA66) blends as an example, the clay can not only affect the phase morphology in immiscible polymer blends, but also frozen in the phase inversion. By adjusting the processing method, an inversed phase, where the minor component PA66 forms the continue phase and the major component PPS forms the dispersed phase, is observed for the first time. This is explained as due to the locking effects of clay layers on the phase development. The result is interesting and also very important, which provides a new way to control the phase morphology and phase inversion in immiscible polymer blends by using clay.

To achieve a good biocompatibility, two sets of novel segmented polyurethanes, namely, poly(ether urethane)s and poly(carbonate urethane)s, with long side chain fluorinated alkyl phosphatidylcholine polar head groups attached to hard block have been synthesized recently in our laboratory by using a new diol with a long side chain fluorinated alkyl phosphatidylcholine polar head group 2-[2-[2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-10-ethoxy-decyloxy]- N -(2-hydroxy-1-hydroxymethyl-1-methyl-ethyl)-acetamide] phosphatidylcholine, HFDAPC as an extender. These novel polyurethanes have shown a potential to be used as bio-membrane mimicry. In this article we investigated the phase behavior of these materials by Instron, DSC, DMA, and AFM because the phase behavior has a great effect on the surface properties thus the biological-related perspective. T g decreases first then increases for the poly(carbonate urethane)s, but increases first then decreases for the poly(ether urethane)s with an increasing in fluorinate phosphatidylcholine content. On the other hand, the tensile modulus was found decrease for the poly(carbonate urethane)s but increase for the poly(ether urethane)s with an increasing in fluorinate phosphatidylcholine content. It was found via AFM that the phase separation increases in poly(ether urethane)s but phase mixing increases in poly(carbonate urethane)s, with increasing content of fluorinated phosphatidylcholine side chain. The interaction between hard and soft segment, particularly, the hydrogen bonding was investigated by FTIR. The effect of fluorinated phosphatidylcholine side group on the phase separation of polyurethane was discussed and compared with that of fluorinated polyurethanes containing only fluorinated side chains. Our result demonstrated how the phase behavior of polyurethanes could be controlled by tailoring the interaction between hard and soft segment.

Various lamellar orientations of high-density polyethylene (HDPE), due to competition between bulk nucleation and interfacial nucleation, have been realized in its melt drawn blends with isotactic polypropylene (iPP) upon cooling after subjected to 160 °C for 30 min. Directed crystallization, with heterogeneous nucleation in the bulk (within domains), is defined as lamellar growth along boundary of anisotropic domains and is favored in larger domains at higher temperature (slow cooling), since overgrowth of lamellae can feel the interface rather than impingement with neighbor ones as a result of scare nuclei at higher temperature. Moreover, lamellar growth caused by directed crystallization is dependent of dimension of confinement. Due to 2D confinement of cylindrical domains, lamellae can only grow along the axis of cylinder and thus b-axis orientation is formed. While in the layered domains with 1D confinement, however, lamellae grow with the normal of (110) plane along the melt drawn direction. On the other hand, epitaxial growth of HDPE chains onto iPP lamellae is related to the surface-induced crystallization and dominated by the interfacial nucleation. Only interfacial nucleation is preferred can epitaxial growth occur. Therefore, retarded crystallization, realized by either strong confinement in finer domains or rapid cooling or both, is favorable for it.

In this article, tensile properties have been discussed in terms of phase morphology, crystallinity and molecular orientation in the HDPE/iPP blends, prepared via dynamic packing injection molding, with aid of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) as well as two dimensional X-ray scattering (2D WAXS). For the un-oriented blends, the tensile properties (tensile strength and modulus) are mainly dominated by the phase morphology and interfacial adhesion related to the influenced crystallization between HDPE and iPP component. A maximum in tensile strength and modulus is found at iPP content in the range of 70–80 v/v%. As for the oriented blends, however, the presence of dispersed phase in the blends, independent of phase morphology and crystallinity, always makes tensile properties to be deteriorated through reducing molecular orientation of matrix. It is molecular orientation of matrix that determines the tensile properties of oriented blends. In the blends with HDPE as matrix, steep decreasing of tensile properties is related to the rapid reducing of molecular orientation of HDPE, whereas in the blends with iPP as a major component, slight decreasing of molecular orientation of iPP results in slight reducing of tensile properties. Other factors, such as interfacial properties and phase morphology, seem to be little contribution to the modulus and tensile strength.

A well-exfoliated morphology is usually observed for polar polymer/clay nanocomposites via dynamic melt processing techniques, whereas only an intercalated or a partially intercalated/partially exfoliated morphology is often obtained for nonpolar polymer/clay nanocomposites, even though some polar compatibilzer is used. In this study, an accelerated exfoliation effect was observed for the first time in iPP/organoclay nanocomposites prepared through so-called dynamic packing injection molding, in which the specimen is forced to move repeatedly in a chamber by two pistons that move reversibly with the same frequency as the solidification progressively occurs from the mold wall to the molding core part. The disordered level and exfoliated degree of clay was found to dramatically increase from the skin to the core of the prepared samples and eventually the WAXD reflections of interlayer d-spacing diminished in the core. The changed degree of exfoliation was also proved directly by TEM observation. The prolongation of processing time, the gradual growth of solidification front, the increased melts viscosity, and the shear amplification effect were considered to explain the higher degree of exfoliation in the center zone of mold chamber. Our result suggests that a critical shear force may be needed to break down clay into exfoliated structure. This can be also well used to explain at least partially the intercalated morphology, which is commonly observed for nonpolar polymer/clay nanocomposites via conventional processing. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2005–2012, 2005

In this study, blends of metallocene short-chain branched polyethylene (SCBPE) with low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene (PS), ethylene–propylene–diene monomer (EPDM), and isotactic polypropylene (iPP) were prepared in weight proportions of 80 and 20, respectively. The crystallization behaviors of these blends were studied with polarized light microscopy (PLM) and differential scanning calorimetry. PLM showed that SCBPE/LDPE, SCBPE/HDPE, and SCBPE/EPDM formed band spherulites whose band widths and sizes were both smaller than that of pure SCBPE. No spherulites were observed, but tiny crystallites were observed in the completely immiscible SCBPE/PS, and the crystallites in SCBPE/iPP became smaller; only irregular spherulites were seen. The crystallization kinetics and mechanical properties of SCBPE were greatly affected by the second polyolefin but in different way, depending on the phase behavior and the moduli of the second components. SCBPE may be phase-miscible in the melt with LDPE, HDPE, and EPDM but phase-separated during crystallization. A big change in the crystal morphology and crystallization kinetics existed in the SCBPE/iPP blend. The mechanical properties of the blends were also researched with dynamic mechanical analysis (DMA). DMA results showed that the tensile modulus of the blends had nothing to do with the phase behavior but only depended on the modulus of the second component. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1816–1823;2005