			Home About us Contact

Miscible Blends (miscible + blend)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Crystallization of Poly(, -caprolactone)/Poly(vinyl chloride) Miscible Blends Under Strain: The Role of Molecular Weight

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 18 2006
Yubao Zhang
Abstract Summary: The effect of poly(, -caprolactone) (PCL) molecular weight on the orientation of crystalline PCL in miscible poly(, -caprolactone)/poly(vinyl chloride) (PCL/PVC) blends, melt crystallized under strain, has been studied by a combination of wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS) studies. An unusual crystal orientation with the b-axis parallel to the stretching direction was observed in miscible PCL/PVC blends with PCL of high molecular weight (>21,000). SAXS showed the presence of nanosize confined PCL in the PCL/PVC blends, which could be preserved at temperatures higher than the Tm of PCL but lower than the Tg of PVC. A mechanism based on the confinement of PCL crystal growth was proposed, which can explain the formation of b-axis orientation in PCL/PVC blends crystallized under strain. SAXS pattern of stretched PCL/PVC blend after annealing at 90,°C for 5 min. [source]

Partially miscible poly(lactic acid)- blend -poly(propylene carbonate) filled with carbon black as conductive polymer composite

POLYMER INTERNATIONAL, Issue 9 2008
Wang Ning
Abstract BACKGROUND: Conductive polymer composites (CPCs) can be obtained by filling polymer matrices with electrically conductive particles, and have a wide variety of potential applications. In the work reported, the biodegradable polymer poly(lactic acid) (PLA) as a partially miscible blend with poly(propylene carbonate) (PPC) was used as a polymer matrix. Carbon black (CB) was used as the conducting filler. RESULTS: Fourier transform infrared spectroscopy revealed interactions between matrix and CB filler; this interaction was stronger in PPC- blend -CB than in PLA- blend -CB composites. A rheology study showed that low-viscosity PPC could improve the fluidity of the CPCs, but decrease that of CB. With increasing CB content, the enforcement effect, storage modulus and glass transition temperature increased, but the elongation at break decreased. CPCs exhibited the lowest electrical percolation thresholds of 1.39 vol.% CB when the content of PPC in PLA- blend -PPC was 40 wt%. The conductivity of CPCs containing 5.33 vol.% CB and 40 wt% PPC reached 1.57 S cm,1. Scanning electron microscopy revealed that CB exhibits a preference for dispersion in the low-viscosity phase (PPC) of the multiphase matrix. CONCLUSION: In the presence of CB, partially miscible PLA- blend -PPC could form multi-percolation CPCs. Moreover, the combination of PLA and PPC with CB broadens novel application of both renewable polymers and CPCs. Copyright © 2008 Society of Chemical Industry [source]

Morphology and mechanical properties of blends of polycarbonate and segmented copolyetherester

POLYMER ENGINEERING & SCIENCE, Issue 2 2000
M. Gaztelumendi
The solid state features and the mechanical properties of melt mixed polycarbonate (PC)/segmented copolyetherester (CPEE) blends were investigated over the full composition range. The partially crystallized blends were composed of two amorphous phases but with only small composition differences in most blend compositions. The specific interactions, and the free volume decreases observed, gave rise to a decrease in the , relaxation strength. The dependence on composition of both the decreases in the , relaxation strength and in the free volume, as well as that of the modulus of elasticity and yield stress, were very similar to those of miscible blends. The nature of the amorphous phases of the blends at room temperature, changed from glassy to partially rubbery as the CPEE content was increased. As a consequence, to discuss the plots of the properties against composition at room temperature, the properties of the rubbery materials in the glassy state had to be determined. The synergistic modulus and yield stress behaviors appeared to be mainly determined by the , relaxation strength and specific volume decrease, and that of ductility additionally by the Tg change. [source]

FT-IR Investigation into the miscible interactions in new materials for optical devices

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2003
Lakshmi Sharma
Abstract In this article we determine the miscibility of azobenzene derivative (poly(4-(N-(2-methacryloyloxyethyl)-N-ethylamino)-4,-nitroazobenzene)90 -co-(methyl methacrylate)10)/poly(vinyl acetate) (PVAc) and azobenzene derivative/poly(vinyl chloride) (PVC) blends using Fourier Transform infrared (FT-IR) spectroscopy. With this method we can clearly identify the exact interactions responsible for miscibility. In the azobenzene derivative 50:50PVAc blend new peaks were evident at 2960, 2890, 1237 and 959,cm,1, these peaks depict miscible interactions. These wavenumbers indicate that the miscible interactions occurring are from the CH stretching band, the vinyl acetate CO, conjugated to the ester carbonyl, the cis-transformation NN stretch frequency and the acetate ester weak doublet. The azobenzene derivative 80:20PVC blend display peaks identical in profile to the blend homopolymers, indicating no miscible interactions. However, this could be due to overlapping of peaks within the same wavenumber region, making resolution difficult. This research demonstrates FT-IR can deduce favorable interactions for miscibility and therefore numerous miscible blends can successfully be calculated if possessing the same groups responsible for miscibility. This paves the way for a new generation of designer optical materials with the desired properties. Copyright © 2003 John Wiley & Sons, Ltd. [source]