Ultradrawing Properties of Ultra-high Molecular Weight Polyethylene/Functionalized Carbon Nanotube Fibers

100學年度研究獎補助論文[[abstract]]Systemic investigation of the influence of the plain and functionalized carbon nanotube (CNT) contents on the ultradrawing properties of ultrahigh molecular weight polyethylene/carbon nanotubes (UHMWPE/CNTs, FCy) and UHMWPE/functionalized CNTs (FCfx-y) as-prepared fibers are reported. In a way similar to those found for the orientation factor values, the achievable draw ratios (Dra) of the FCy and FCfx-y as-prepared fibers approached a maximum value as their CNT and/or functionalized CNT contents reached their corresponding optimum values. The maximum Dra values obtained for FCfx-0.001 as-prepared fiber specimens prepared at varying maleic anhydride grafted polyethylene (PE-g-MAH)/modified CNTs weight ratios were significantly higher that of the FC0.0015 as-prepared fiber specimen prepared at the optimum plain CNT content. Tensile property analysis further suggested that excellent orientation and tensile properties of the drawn FCy and FCfx-y fibers can be obtained by ultradrawing the fibers prepared at their optimum plain CNT and/or functionalized CNT contents. To understand the interesting orientation, ultradrawing and tensile properties of FCy and FCfx-y fiber specimens, FTIR, specific surface area, and SEM morphology analysis of the plain and functionalized CNTs were performed in this study.[[journaltype]]國外[[incitationindex]]SCI[[booktype]]紙本[[countrycodes]]US

Influence of Drawing Conditions on the Ultradrawing Properties of Film Specimens of Ultrahigh Molecular Weight Polyethylene and Low Molecular Weight Polyethylene Blends

The influence of the drawing temperature and rate on the ultradrawing properties and deformation mechanisms of a series of film specimens prepared from varying concentrations of gel solutions of ultrahigh molecular weight polyethylene (UHMWPE) and low molecular weight polyethylene (LMWPE) blends is reported. The maximum achievable draw ratio was obtained when each UHMWPE/LMWPE film specimen was drawn at an optimum temperature (T op), wherein the T op values of each UHMWPE/LMWPE film specimen increased consistently with the drawing rate. The temperature dependence of the apparent elongational viscosity (a) revealed two distinguishable intervals with different activation energies. Coincidentally, the transition temperature (T r) obtained from the intersection of the two straight lines drawn parallel to the two distinct intervals is approximately equal to the T op value found for the film sample drawn at the same rate. Dynamic mechanical analysis of the film samples exhibited an extraordinary high transition peaked at temperatures near 95–115C, which are again very close to the T op and T r values found for the film samples drawn at varying rates, and increases significantly with the testing frequencies. Possible mechanisms accounting for these interesting deformations, temperature dependence of the apparent elongational viscosity and dynamic mechanical properties are suggested in this study.補正完畢國外SCI紙本NL

Plasticized Properties of Poly(lactic acid) and Triacetine Blends

[[abstract]]Systematically investigations of the plasticizing effects of triacetine (TAc) on crystallization, chain mobility, microstructure, and tensile properties of the Poly (lactic acid)/triacetine (PLA/TAc) blends are reported. A new transition hump was observed on the tan curve of PLAxTAcy specimens at temperatures ranging from -80 to -20°C. Thermal, wide angle X-ray diffraction (WAXD) and dynamic mechanical analysis properties of PLA and PLAxTAcy series specimens suggest that PLA and PLAxTAcy series specimens can hardly crystallize by cooling the melt in room temperature. However, significant recrystallization of form PLA crystals was found during the annealing processes of PLAxTAcy series specimens. Some less perfect form PLA crystals were found as the TAc contents of PLAxTAcy specimens reach 30 wt %. Further morphological analysis show that the inherent brittle deformation behavior of the PLA specimen was successfully transformed into relatively ductile fracture behavior after blending sufficient but optimum amounts of TAc in PLA resins. Possible reasons accounting for this interesting recrystallization, thermal, microstructure and tensile properties of PLAxTAcy specimens are proposed.[[notice]]補正完畢[[incitationindex]]SCI[[incitationindex]]SSC

The permeation resistance of polyethylene, polyethylene/polyamide and polyethylene/modified polyamide blown tubes against unleaded gasoline

[[abstract]]The barrier resistance of polyethylene (PE), polyethylene/polyamide (PE/PA) and polyethylene/modified polyamide (PE/MPA) blown tubes against gasoline permeation is reported. The blown tubes prepared from pure PE exhibited much poorer gasoline permeation resistance than PE/PA and PE/MPA blown tubes. About 93% of the filled gasoline permeated out of PE blown tubes in 14 days at 40�C. In contrast, the gasoline permeation resistance of the blown tubes improved significantly by blending MPA (or PA) before tube blowing. PE/MPA blown tubes exhibited significantly better gasoline permeation resistance than PE/PA blown tubes of the same PE contents. The order of gasoline permeation resistance of PE/MPA blown tubes is the same as the order of the barrier resistance of MPA resins against gasoline permeation before blending with PE. In fact, by using proper compositions and carefully controlling the MPA morphology, the gasoline permeation resistance of the PE/MPA blown tubes can reach about 360 times better than that of pure PE blown tubes at 25�C. These interesting phenomena were investigated in terms of the morphology, thermal and rheological properties of the base resins and/or blown tubes of PE/PA and PE/MPA blends.[[notice]]補正完畢[[incitationindex]]SC

Influence of compositions of modified blends of polyamide/poly(vinyl alcohol) on the methanol/gasoline fuel barrier properties of polyethylene/modifiedblends of polyamide/poly(vinylalcohol) bottles

[[abstract]]Polyamide (PA), poly(vinyl alcohol) (PVA) and the blends of PA and PVA were modified by a compatibilizer (CP) to make modified polyamide (MPA), modified PVA (MPVA) and modified PA/PVA (MPAPVA) blends through reactive extrusion. The MPVA and MPA hot-pressed sheets exhibit the best and worst methanol/gasoline fuel permeation resistance among these modified resins, which show much better methanol/gasoline fuel permeation resistance than pure PE resin. It is worth noting that the methanol/gasoline fuel permeation resistance of MPAPVA sheets improves consistently with their PVA contents. Similarly, after blending these barrier resins with PE, the methanol/gasoline fuel permeation resistance of the blended bottles improves to become significantly better than that of pure PE bottles. Further investigations found that the hydrocarbon components with 5 to 10 main-chain carbon atoms present in methanol/gasoline fuels were successfully blocked during the permeation tests. However, the order of barrier improvement of PE/MPA, PE/MPAPVA and PE/MPVA bottles does not completely correspond to the order of the barrier improvement of the base barrier resins before blending and blow-molding with PE. For instance, the PE/MPVA and PE/MPAPVA bottle series with a PVA/PA weight ratio of 4 : 1 exhibit poorer methanol/gasoline fuel permeation resistance than all the other PE/MPAPVA bottles, although the base MPVA and MPAPVA with a 4 : 1 PVA/PA weight ratio are associated with better permeation resistance than the other MPAPVA resins prepared in this study. These interesting phenomena were investigated in terms of the melt shear viscosities, chemical structure and morphology of the barrier resins present in their corresponding bottles.[[notice]]補正完畢[[journaltype]]國外[[incitationindex]]SC

Oxygen Barrier and Blending Properties of Blown Films of Blends of Modified Polyamide and Polyamide-6 Clay Mineral Nanocomposites

[[abstract]]Investigations of oxygen barrier and blending properties of the modified polyamide (MPA) and nylon-6 clay (NYC) blends (MPANYC) were systematically investigated. After blending NYC in MPA, the oxygen barrier properties of the MPANYC film specimens are significantly better than those of the MPA and NYC film specimens. At 20 wt.% optimum content of NYC, the oxygen barrier improvement of MPANYC film specimen reaches the maximum, which is in the same order of magnitude of barrier improvement as those of PVDC film specimens. A similar relation on the NYC content was found on the plots of free free-volume properties (i.e. Rf, Vf, I3 and Fv) vs. the NYC contents of MPANYC specimens. The minimum Rf, Vf, I3 and Fv values of MPANYC specimens were found as their NYC contents reach about 20 wt.%. The characteristic X-ray reflections of α form PA crystals originally associated with the MPA resin almost disappear after blending varying amounts of NYC in MPA resins. Further morphological investigations showed that demarcated structures of elongated (ca. 700 nm) and overlapped clay mineral layers were found on the microtomed surfaces of MPANYC specimens as their NYC contents reach 20.0 wt.%. However, at NYC contents lower than 20.0 wt.%, the lengths of these “elongated and overlapped” clay mineral layers reduce significantly as the NYC contents continue to reduce. These improved oxygen barrier properties of the MPANYC film specimens were explained in terms of the reduced free-volume properties and demarcated structures of the elongated and overlapped clay mineral layers caused by the presence of the nanometer clay mineral layers.[[notice]]補正完

Study on the Crystallization, Miscibility, Morphology, Properties of Poly(lactic acid)/Poly(ε-caprolactone) Blends

[[abstract]]A series of blends of poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) with different mass ratio were prepared by means of the melt blending method to study their crystallization, miscibility, morphology, and thermal and mechanical properties. The result of DSC tests showed that the melting temperatures of PLA and PCL shifted toward each other, and that the largest shift appeared at the PLA70PCL30 blend. This result reveals that the PLA70PCL30 blend gives the strongest interaction intensity among the blends. Combined the result of dynamic mechanical analysis and SEM morphologies, it was found that PLA and PCL form a partial miscible blend, in which an amount of amorphous PCL (amorphous PLA) is dissolved in the PLA-rich phase (PCL-rich phase), leading to a depression of the Tg. value. The polarized optical micrographs showed that PCL can serve as a nucleating agent to promote PLA crystallization in the PLA/PCL blend. Moreover, the PLA70PCL30 blend gave the largest growth rate of PLA spherulite. Finally, the mechanical property of PLA/PCL blends indicated that PLA can easily be tuned from rigid to ductile by the addition of PCL.[[journaltype]]國外[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]紙本[[countrycodes]]US

Blending and Barrier Properties of Blends of Modified Polyamide and Ethylene Vinyl Alcohol Copolymer

ABSTRACT: The blending and barrier properties of the MPAEVOH blends of modified polyamide (MPA) and ethylene vinyl alcohol copolymer (EVOH) were systematically investigated in this study. After blending MPA in EVOH resin, a noticeable "negative deviation" was found on the plot of the oxygen permeation rate versus MPA content when the MPA contents present in MPAEVOH resins reach about 80 wt %. The peak temperatures associated with the main melting endotherm of MPA and EVOH reduce significantly with increasing the EVOH and MPA contents present in MPAEVOH resins, respectively. The melting endotherm and X-ray diffraction peak associated with EVOH crystal phases disappear gradually as the MPA contents present in MPAEVOH increase. In fact, the melting endotherm and X-ray scattering peak corresponding to EVOH crystals almost disappear as the EVOH contents present in MPAEVOH specimens are less than 20 wt %. Further Fourier-Transform Infrared (FT-IR) investigations indicate that the strengths of intermolecular hydrogen bonds of MPAEVOH specimens reduce significantly as the MPA contents increase, wherein the self-associated hydroxyl-hydroxyl bonds within EVOH resins almost disappear as the EVOH contents reduce to be less than about 20 wt %. As expected, the average sizes of the free volume holes of MPAEVOH specimens increase significantly as the MPA contents increase. However, somewhat surprisingly, a clear negative deviation was found on the plot of the numbers and fractional free volumes of free volume holes against the MPA contents as the EVOH contents are close to about 20 wt %. The interesting barrier properties of the MPA, EVOH, and MPAEVOH specimens were investigated in terms of the free volume and intermolecular interaction properties in the amorphous phases of MPAEVOH specimens described above