Phase Morphology and Miscibility of iPP/PcBR Blends

Isotactic polypropylene/poly(cis-butadiene) rubber (iPP/PcBR) blends were prepared by melt mixing. Phase morphology of the blends was investigated by scanning electronic microscopy (SEM). It was found that the dispersed phase spread in continuous phase in a form of spherical particles. The size of the dispersed phase increased as its content increased. The phase-inversion region was the composition of 50/50 and 40/60 vol% in the blends. In the phase-inversion region, a double continuous phase was formed. The glass transition temperatures (T _g ) of iPP, PcBR and blends were analyzed by dynamic mechanical analysis (DMA). The blend compositions exhibited two distinct glass transition temperatures corresponding to the iPP-rich and PcBR-rich phases, respectively. The approach of these two peaks with increasing PcBR content indicated partial miscibility between the iPP and PcBR, which was verified by the equilibrium melting point depression of blends.     

Blends of high density polyethylene and ethylene/1‐octene copolymers: Structure and properties

The morphology formation in the blends comprising a high density polyethylene (HDPE) and selected ethylene/1‐octene copolymers (EOCs) was studied with variation of blend compositions using atomic force microscopy (AFM). The binary HDPE/EOC blends studied showed well phase‐separated structures (macrophase separation) in consistence with individual melting and crystallization behavior of the blend components. For the blends comprising low 1‐octene content copolymers, the lamellar stacks of one of the phases were found to exist side by side with that of the another phase giving rise to leaflet vein‐like appearance. The formation of large HDPE lamellae particularly longer than in the pure state has been explained by considering the different melting points of the blend components. The study of strain induced structural changes in an HDPE/EOC blend revealed that at large strains, the extensive stretching of the soft EOC phase is accompanied by buckling of HDPE lamellar stack along the strain axis and subsequent microfibrils formation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1887–1893, 2007     

Confocal Scanning Laser Microscope Image of Gradient Structure Formed in an Acrylate Copolymer/Fluoro-copolymer Blend

Thin films of poly(2-ethylhexyl acrylate-co-acrylic acid-co-vinyl acetate)/poly(vinylidene fluoride-co-hexafluoro acetone) [P(2EHA-AA-VAc)/P(VDF-HFA)] of 30/70 (by weight) blends without and with addition of 2 wt% fine silica gel were prepared on poly(ethylene terephthalate) (PET) from 20 wt% THF solution. Gradient domain morphology formed in the 30/70 blend was observed with a confocal scanning laser microscope (CSLM). Separate domains composed of P(2EHA-AA-VAc) phase were found in P(VDF-HFA) matrix at various levels of increasing depth with increasing domain size. Thus, CSLM is quite effective in morphological observation of the gradient structure formed in polymer blends, provided the blends are transparent.     

Imaging the Kidney with an Unconventional Scanning Electron Microscopy Technique: Analysis of the Subpodocyte Space in Diabetic Mice

Transmission electron microscopy (TEM) remains the gold standard for renal histopathological diagnoses, given its higher resolving power, compared with light microscopy. However, it imposes several limitations on pathologists, including longer sample preparation time and a small observation area. To overcome these, we introduced a scanning electron microscopy (SEM) technique for imaging resin-embedded semi-thin sections of renal tissue. We developed a rapid tissue preparation protocol for experimental models and human biopsies which, alongside SEM digital imaging acquisition of secondary electrons (SE–SEM), enables fast electron microscopy examination, with a resolution similar to that achieved by TEM. We used this unconventional SEM imaging approach to investigate the subpodocyte space (SPS) in BTBR ob/ob mice with type 2 diabetes. Analysis of semi-thin sections with secondary electrons revealed that the SPS had expanded in volume and covered large areas of the glomerular basement membrane, forming wide spaces between the podocyte body and the underlying filtering membrane. Our results show that SE–SEM is a valuable tool for imaging the kidney at the ultrastructural level, filling the magnification gap between light microscopy and TEM, and reveal that in diabetic mice, the SPS is larger than in normal controls, which is associated with podocyte damage and impaired kidney function.     

Behavior of Deformed Droplets in an Immiscible Polymer Blend: A Comparative Study of Electron Microscopy and Small‐Angle X‐Ray Scattering

The deformation of dispersed droplets in a PS/LLDPE 95:5 blend during uniaxial elongation and after cessation of the flow was studied. The behavior of the dispersed droplets during elongation is in a good agreement with a prediction of the modified capillary number model using transient elongational viscosities. The phase structure changes after the elongation was studied in relaxation and recovery modes. The morphology was investigated using scanning electron microscopy and small‐angle X‐ray scattering. Thus the dimensions of the dispersed particles and their degree of orientation were estimated. It was shown that the SAXS as an integral method gives new additional information which is hardly accessible by SEM as a method providing local information about discrete locations in the sample. The results of both methods proved that the stress in the sample is a decisive parameter determining the morphology development after cessation of the flow.

     

同向双螺杆熔体输送段捏合盘错列角对不相容体系共混物相态结构的影响

对啮合同向双螺杆挤出机,将捏合盘置于熔体输送段,通过改变捏合盘错列角,研究双螺杆挤出过程熔体输送段捏合盘错列角对不相容体系共混物相态结构的影响。应用差示扫描量热仪对两相共混体系HDPE/PS的热性能进行了实验研究,结果表明:螺杆构型对共混物的相容性影响不大。同时采用扫描电子显微镜考察了HDPE/PS共混物在熔体输送段末端位置和机头末端所取试样的相态结构,研究表明:置于熔体输送段捏合盘元件错列角对共混物分散相的相畴尺寸有一定影响。     

Blends of sulphonated polystyrene and polystyrene: Morphology and deformation modes

Blends of sulphonated polystyrene, neutralized with metal ions, have been prepared in various proportions with polystyrene homopolymer. Morphology, microstructure, and deformation modes of strained, cast thin films have been examined by transmission electron microscopy. Variables studied include blend composition and ion content. In blends of low ionomer concentration, the ionomer component phase-separates and takes the form of small dispersed particles. With the increase of ion content, the average particle size increases and, as crazes develop in the matrix, particles elongate and fibrillate. These ionic crosslinked particles adhere well to the matrix, share in carrying the applied stress and reinforce the matrix polymer. Implications of these results for mechanical performance of bulk samples are discussed.     

Phase separation induced morphology evolution andcorresponding impact fracture behavior of iPP/PEOc blends

In this study, the influence of phase separation on impact toughness of isotactic polypropylene (iPP)/poly(ethylene‐co‐octene) (PEOc) blends was investigated. For the typical toughened polymeric system, three iPP/PEOc compositions (80/20, 70/30, and 60/40) were selected. When the polymeric blends were annealed at 200°C, the coarsening of phase domains was more prominent for the blend containing higher content of PEOc, and the scale of its morphological evolution was increased as well. The impact test showed that the impact strength variation trend as a function of annealing time was closely related to morphological evolution. It was believed that the sharpening of phase boundary and coarsening of phase domains were responsible for the depression of impact toughness, and the probable fracture mode alteration from shear banding to crazing and voiding. Structure evolution induced by phase separation showed an important effect on impact toughness, and it was also affected by the environmental conditions. Proper temperature was required to catch the tough‐brittle transition induced by phase separation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Examination of the Aging Effects of Silicone Molds During Vacuum Casting Processes via Scanning Electron Microscopy

We present an in-depth investigation of contaminated silicone molds by use of scanning electron microscopy, that provides additional insight into the aging process of the molds. The molds lifetime in vacuum casting processes of polyurethane is limited due to contamination with the diisocyanate compound of the PUR resin. SEM investigations, combined with FIB cross-sections and EDX measurements show that three different types of particles are distributed in the contaminated silicone matrix. The particles differ in shape and size, with a range from 50 nm to 50 µm. This explains the loss in transparency and the hardened haptics of contaminated molds.     

Interrelation of Scanning Electron Micrographs with Flexural Behavior of Ferrite and Nano-Barium Titanate Reinforced Poly-Ether-Ether-Ketone (PEEK) Composites

ABSTRACT

The flexural behavior of ferrite filled poly-ether-ether-ketone (PEEK) composites, with and without reinforcement of nano-barium titanate, was studied and was corroborated through scanning electron microscopy (SEM). In this study, ferrite filled PEEK, and ferrite and nano-barium titanate reinforced PEEK composites were prepared. Ferrite filled PEEK composites showed reduction in flexural strength and increase in flexural modulus with the increase in ferrite content, whereas, with the reinforcement of nano-barium titanate, flexural strength increased and flexural modulus decreased at similar ferrite content. The SEM micrographs corroborated well with flexural behavior, as ferrite particles and smooth topographic surfaces of brittle fracture were evident in the samples having higher ferrite content in ferrite filled PEEK composites, whereas, typical yield pattern of crust and trough on fractured topographic surfaces of ferrite and nano-barium titanate, reinforced PEEK composites, was visible.     

Morphology and Thermal Properties of Compatibilized PA12/PP Blends with Boehmite Alumina Nanofiller Inclusions

Boehmite alumina nanoparticles are added to PP‐g‐MAH‐compatibilized blends of PA 12 and PP to study the effects of nanoparticle loading in the resulting composites. WAXD and SEM data suggest that the nanoparticles enhanced the coalescence of PP. DSC, DMA, and TGA reveal that the final properties such as crystallization temperature, flexural storage modulus, thermal degradation temperature, etc., improve with increasing nanoparticle loading for blend/based composites. FTIR results show that the nanoparticles interfere with the interfacial activity at 5 wt% nanoparticle loading. All results are compared between the neat polymers and the compatibilized blend and show that despite a slight increase in dispersed‐phase domain size, all other properties improve with the addition of AlO(OH).

     

扫描电子显微镜的结构及对样品的制备

扫描电子显微镜作为一种有效的分析工具,可对多种材料的表面形貌进行观察,使用范围广泛。本文论述了扫描电子显微镜的原理及结构,介绍了样品导电处理的常见方法,重点介绍了离子溅射法和真空蒸发法,并对二者的特点进行了简单总结。     

Structure and Morphology Development in Films of mLLDPE/LDPE Blends During Blowing

Summary: In this work the analysis of the structure orientation, morphology, relaxation time and optical properties of blown films of mLLDPE, LDPE and their blends were performed by using WAXD, SALS, AFM, DSC and rheological and haze tests. For mLLDPE film, the crystals do not present “a”‐axis orientation along the machine direction; a distinct spherulite like superstructure is seen. The film surface is very rough. The values of bulk and surface haze are higher than LDPE and blends, whereas the relaxation time is lower. For LDPE film the (110) planes are parallel and at same time twisted with respect to the layer of the film with the “a”‐axis well oriented along the machine direction. No spherulite superstructure is observed and the surface of the film is more regular. High values of relaxation time are observed. The surface haze is the predominant contribution to the total haze. For the blend films no clear and distinct spherulite structures are observed. The orientation degree increases with composition never approaching that of LDPE. The surface is very more regular and smooth than that of the pure polymers. The haze values are below the values of pure materials. It was underlined that bulk and surface morphology and orientation degree of the crystalline planes along the machine direction dictate the optical properties of the films. Moreover both orientation and morphology are defined by the PE molecular and melt rheology characteristics, processing conditions and blend composition.

Total, bulk and surface haze of mLLDPE/LDPE blend films as a function of composition.     

Using Nanosilica to Fine‐Tune Morphology and Properties of Polyamide 6/Poly(propylene) Blends

The effect of hydrophilic and hydrophobic nanosilica on the morphological, mechanical and thermal properties of polyamide 6 (PA) and poly(propylene) (PP) blends is investigated by extrusion compounding. Depending on the difference between the polymer/nanoparticle interfacial tensions, different morphologies are obtained as highlighted by TEM and SEM. Hydrophobic nanosilica migrates mainly at the PA/PP interface, which leads to a clear refinement of PP droplet size. The macroscopic properties of the hybrid blends are discussed and interpreted in relation with the blend morphology and melt‐mixing procedure. The control over coalescence allows a morphology refinement of the blends and improves mechanical properties.

     

Morphology and elastic properties of PP/EVA polymer blends

Several polypropylene–ethylene vinyl acetate (PP/EVA) copolymers with compositions ranging from 90/10 to 10/90 PP/EVA were prepared and characterized in terms of their morphology by transmission and scanning electron microscopy, and their mechanical properties were also studied. The results show a wide range of spatial structures which correlate well to the corresponding measurements of elastic modulus of the blends.     

Mechanical Properties and Morphology of Ternary PP/EPDM/PE Blends

The ternary blends of high‐density polyethylene (PE), EPDM terpolymer and polypropylene (PP) have been used as a model low interfacial tension system to study encapsulation dynamics in ternary blends and their relation to the blends' mechanical properties. It was found that the modulus, tensile strength and impact resistance can be improved by PE addition if the PE is localized within the EPDM phase. A range of blend morphology was found depending on the PE viscosity and polymer incorporation sequence in the twin‐screw extruder. In the most favorable sequence, PE and EPDM were mixed together prior to their dispersion in the PP matrix. This practice resulted in a 50% increase in impact resistance when compared to mixing the three components in a single‐step.     

Effect of Sample Configuration on the Morphology of Foamed LDPE/PP Blends Injection Molded by a Gas Counterpressure Process

Blends of isotactic poly(propylene) and low‐density polyethylene with different composition ratios were prepared through direct melt compounding on a twin‐screw extruder. The specimens with various geometric configurations were injection‐molded using a gas counterpressure process, using blends to which 0.5 wt.‐% of a blowing agent was added. The influence of blend composition and specimen geometry on the structure and morphology of the samples was investigated by SEM and WAXS. The thermal behavior of the blends was analyzed by DSC. It was found that the morphology of each region depended on the composition ratio and specimen geometry.

     

Effect of Organoclay on the Morphology and Properties of Poly(propylene)/Poly[(butylene succinate)‐co‐adipate] Blends

The effect of organically modified clay on the morphology and properties of poly(propylene) (PP) and poly[(butylene succinate)‐co‐adipate] (PBSA) blends is studied. Virgin and organoclay modified blends were prepared by melt‐mixing of PP, PBSA and organoclay in a batch‐mixer at 190 °C. Scanning electron microscopy studies revealed a significant change in morphology of PP/PBSA blend in the presence of organoclay. The state of dispersion of silicate layers in the blend matrix was characterized by X‐ray diffraction and transmission electron microscopic observations. Dynamic mechanical analysis showed substantial improvement in flexural storage modulus of organoclay‐modified blends with respect to the neat polymer matrices or unmodified blends. Tensile properties of virgin blends also improved in the presence of organoclay. Thermal stability of virgin blends in air atmosphere dramatically improved after modification with organoclay. The effect of organoclay on the melt‐state liner viscoelastic properties of virgin blends was also studied. The non‐isothermal crystallization behavior of homopolymers, virgin, and organoclay‐modified blends were studied by differential scanning calorimeter. The effect of incorporation of organoclay on the cold crystallization behavior of PP/PBSA blends is also reported.

     

Optimization of an Electrochemical DNA Assay by Using a 48‐Electrode Array and Redox Amplification Studies by Means of Scanning Electrochemical Microscopy

Sensible DNA : An electrochemical DNA assay based on specific Salmonella spp. capture probes and enzyme labeling with alkaline phosphatase was optimized by using a 48‐electrode microarray and scanning electrochemical microscopy (SECM). SECM was further used to evaluate potential amplification strategies due to redox cycling.