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The authors present a simple double patterning technique with I-line stepper to define nanoscale structures and have successfully fabricated n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with sub-100-nm gate length. With this approach, polycrystalline silicon (poly-Si) gate with linewidth down to 80 nm could be formed with good control, which far exceeds the resolution limit of conventional I-line lithography. Moreover, ineffectiveness of end point detection in the second poly-Si gate definition is also addressed. For reliable process control in the second etching step, appropriate mask design is found to be essential. Finally, sub-100-nm MOSFETs with or without halo implemented symmetrically or asymmetrically are fabricated and characterized. [ABSTRACT FROM AUTHOR]

A nanocomposite anode material for lithium batteries is designed and fabricated by the insertion of graphite nanosheets (GNS) into the ceramic network of silicon oxycarbide (SiOC) ceramics for the development of structurally and electrochemically stable lithium batteries. The GNS forms a layered phase in the SiOC ceramic network from the self-assembly of graphite oxides (GO) introduced in a polysiloxane precursor through thermal transformations after pyrolysis. The composite anode (GNS/SiOC) exhibits an initial discharge capacity attaining 1141 mAh g−1. The discharging capacity decreases in the first eight cycles and stays at 364 mAh g−1in the following cycles. This reversible discharging capacity is higher than that of a graphite reference (328 mAh g−1) and a SiOC monolithic. Correlating the discharge capacities to the material compositions and structures suggest that the interface between SiOC and GNS contributes to the enhanced capacity of the composite anode, in addition to those from GNS and SiOC. Further increasing the electrochemical performance is possible by the increase of the amount of GNS in the composite. [ABSTRACT FROM AUTHOR]

Masses of highly uniform silica-shelled carbon nanotube (CNT) coaxial fibers are synthesized in a single step by the catalytic gas-flow reaction method. This method involves the generation of CNTs in the gas flow from the injection catalytic gas flow reactions and the in situdeposition of silica over the gas dispersed CNTs viathe decomposition of a polysiloxane downstream of the CNT flow. Silicone grease consisting of polydimethylsiloxane (PDMS) was used as the precursor for silica. The coaxial fibers produced by this process are highly uniform, with each fiber containing a CNT core enclosed in a uniform silica shell. The growth of silica from PDMS over CNTs is efficient, with ∼50 wt% of PDMS converted into silica. The key controlling factor of the growth of the coaxial fibers is the hydrogen flow, which is required for both the growth of CNTs and the formation of silica from the polysiloxanes. The highly localized deposition of silica over the CNTs with the composition of Si/O in silica close to that of PDMS is likely associated to the condensation from Si–O chains decomposed from PDMS. The silica phase of the coaxial fiber resulting from this process is highly oxygen deficient and, as the result, the coaxial fibers emit strong photoluminescence under ultraviolet excitation. Meanwhile, the silica shell phase is highly hydrogenated, which permits the uniform bonding of nanocrystallines on the fibers. The present process provides an effective means to fabricate high quality silica-CNT coaxial fibers for potential functional applications. [ABSTRACT FROM AUTHOR]

The focus of this work is to investigate the effect of different manufacturing methods on nanoparticles dispersion and rheological properties of polycarbonate (PC) filled nano-calcium carbonate (CaCO3) nanocomposites. Two methods were used to prepare the PC/CaCO3 nanocomposites through twin-screw extruder: one was compounding PC with CaCO3 nano-powder, named PC-CP; another was compounding PC with CaCO3 aqueous suspension, named PC-CAS. The relationship between the processing method and the particle dispersion, matrix molecular weight and rheological properties of the nanocomposite was discussed. Morphological observation showed that nanoparticles were dispersed more homogeneously in PC-CAS. Gel permeation chromatography (GPC) test showed that molecular weight drop of PC-CAS was smaller than PC-CP when CaCO3 content under 2.2 wt%. Melt flow rate (MFR) and capillary rheological behavior indicated the change of rheological property of PC-CP was larger than PC-CAS while CaCO3 content under 2.6 wt%. In general, both the dispersion and rheological property of PC-CAS were better than PC-CP under a reasonable CaCO3 content. [ABSTRACT FROM AUTHOR]

Abstract  In this work, isotactic polypropylene (iPP) composites filled with multiwalled carbon nanotubes (MWCNTs) were prepared by compounding iPP melt with MWCNT aqueous suspension using a corotating twin-screw extruder, and the morphology and crystallization behavior of the composites were investigated. Scanning electron microscopy micrographs showed that MWCNTs dispersed individually at nanoscale in the iPP matrix when the MWCNTs concentration was low, though MWCNTs aggregates were detected when the filler concentration increased. The results of differential scanning calorimetry, wide-angle X-ray diffraction, and polarized light microscopy indicated that the β-form crystal of iPP was induced by MWCNTs at the concentration of 0.1 wt.% which was dispersed individually in the iPP matrix. At higher content, however, MWCNTs acted as α-nucleating agent, and the crystals in the iPP/MWCNT composites showed higher degree of perfection than that of pure iPP though smaller in dimension. Crystallization rate of iPP increased significantly with increasing MWCNT content. [ABSTRACT FROM AUTHOR]

The article discusses challenges with injection molding, also known as "Stefan problems" or "moving-boundary problems." The authors simulate the two-dimensional phase-change heat conduction of the injection molded high density polyethylene (HDPE) parts with thick walls during the cooling stage by means of the Faghri and Cao's enthalpy transformation method. Other topics include predicting the temperature distributions occurring in the cavity during the cooling process as well as the polymer extended phase change temperature range (mushy zone).

A large-size circular-disc (CD) assembly of carbon nanotubes (CNTs) was formed from injection catalytic chemical vapor deposition (CVD) reactions. The CNT-CD assembly, which has an outer diameter of 830 nm, consists of closely packed rings of double-walled carbon nanotubes (DWNTs), in twenty-eight circles, and stacked in five layers. A structural interpretation suggests that the CNT-CD assembly is coiled from a “tape-like” bundle of DWNTs, whose coiling to form the CNT-CD resembles the rolling up of tape to form a disc. The large CD assembly was formed within milliseconds in the transient gas flow reactions, and the coiling of nanotubes or “nucleation” of the circular assembly was associated with shears generated by gas disturbances in the vapor phase. [ABSTRACT FROM AUTHOR]

The rheological properties of PC/EVA blends had been investigated by a Haake torque rheometer. The effects of blending temperature, a polycarbonate and a catalyst on the rheological properties of PC/EVA blends were discussed. The transesterification between PC and EVA, catalyzed by dibutyl tin oxide (DBTO), were investigated by differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The results indicate that the chain break of PC or EVA can be accelerated by DBTO, which induces the equilibrium torque of PC or EVA to decrease as the DBTO content increases. But for the PC/EVA blend, as the blending temperature of increases, the increase of viscosity induced by the generation of the PC-EVA copolymer exceeds the decrease of viscosity induced by the chain break of PC and EVA. Therefore, the equilibrium torque of the PC/EVA blend with varying DBTO content is higher than that of uncatalyzed PC/EVA blend at the higher temperature, 250°C, compared with the lower temperature, 210°C. The content of PC in the blend influences the probability of transesterification and the generation of PC-EVA copolymer. The PC/EVA blend with 50 wt. %PC has the highest torque compared with the other blends. [ABSTRACT FROM AUTHOR]

The tensile and impact properties of glass bead (GB)-filled linear low-density polyethylene (LLDPE) were studied in this article. The tensile stress-strain behaviors of GB-filled LLDPE composites do not show any obvious difference from that of pure LLDPE, but the overall mechanical properties of GB-filled LLDPE composites are improved quite a lot, which demonstrates that in a relatively small bead size range, the inorganic spherical particle can effectively increase the mechanical properties of LLDPE. The elastic modulus and the elongation to break are almost constant for various filler contents, while the yield strength greatly increases when the filler content is very low, and then remains at about that level up to a 20% filler concentration. After a sharp increase when the filler concentration is 5% by weight, the impact strength gradually increases with increasing filler content, and obtains a 40% improvement above the resin, showing significant toughening effect. Combining the effects of bead size and filler concentration studied on the mechanical properties of GB-filled LLDPE composites, it is found that for glass beads with relatively small particle size, the bead size plays a significant role, which seems to be inconsistent with some results from the literature. From investigation of the morphology of the filled specimen, it is found that though the glass beads are not surface treated, the glass beads used present quite good interfacial adhesion with the matrix LLDPE, and the distribution of the bead in the matrix is the main influencing factor on the mechanical properties of the LLDPE composites. [ABSTRACT FROM AUTHOR]

Determines the influences of hot stretching ratio on morphology and tensile properties at a fixed composition. Improvement of the physical properties of polymers; Cause of the extrusion of nylon-polyethylene film; Avoidance of the fracture of polyethylene terephthalate microfibers.

Presents a study that examined the morphology and tensile properties of polycarbonate-polyethylene alloy in phase inversion region. Method of the study; Results and discussion; Conclusion.