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LDPE Phase (ldpe + phase)

Distribution by Scientific Domains

Polymers and Materials Science	75%

Selected Abstracts

Electrical conductivity and rheological behavior of multiphase polymer composites containing conducting carbon black

POLYMER ENGINEERING & SCIENCE, Issue 11 2008
Qinghua Zhang
Multiphase polymer composites of carbon black (CB), polypropylene (PP) and low density polyethylene (LDPE) were prepared by melt-mixing method to reduce the amount of CB in the conductive composites. SEM images showed that CB preferably located in LDPE phase and formed electrically conductive path. The measurement of conductive properties showed that the ternary materials possessed lower percolation than binary composites of CB/PP or CB/LDPE, the former was ,6 wt% and the latter was 9,10 wt%. Positive temperature coefficient (PTC) effects of the binary and ternary composites were investigated, indicating that the latter exhibited a relatively high PTC intensity. A rheological percolation estimated by a power law function is 2.66 wt% of CB loading, suggesting an onset of solid-like behavior at low frequencies. This difference between the electrical and rheological percolation thresholds may be understood in terms of the smaller CB,CB distance required for electrical conductivity as compared with that required to impede polymer mobility. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source]

An experimental study of morphology and rheology of ternary Pglass-PS-LDPE hybrids

POLYMER ENGINEERING & SCIENCE, Issue 6 2003
Peter C. Guschl
Ternary blends of low-density polyethylene (LDPE), polystyrene (PS), and a low Tg tin-based phosphate glass (Pglass) were prepared at compositions ranging from 0,50 vol% Pglass in which either LDPE or PS was the continuous matrix phase. Differential scanning calorimetry was used to investigate the phase behavior of the pure components, PS-LDPE blends and binary Pglass-polymer hybrids. Interesting steady-shear and transient rheology was observed for the hybrids. In particular, the steady shear viscosity curves for the hybrids of ,Pglass , 30% exhibited unusual, four-region flow behavior, similar to that of liquid crystalline polymers. Two Newtonian plateaus at low ( , 0.1 s,1) and moderate (0.4 , , s,1) shear rates connected by two distinct shear-thinning regimes were apparent. This observed rheology is ascribed to a unique composite morphology of these multi-component systems. Rheological data on the binary Pglass-polymer systems suggest that the presence of the Pglass within both PS and LDSE contributes significantly to this unusual behavior, perhaps because of the interfacial behavior between the phases. Micrographs obtained via scanning electron microscopy reveal preferential placement of the Pglass phase dispersed within the PS-phase and surrounding the LDPE phase. Optical shearing data confirmed the evolution of this microstructure under specific shear conditions. [source]

Low density polyethylene and grafted lignin polyblends using epoxy-functionalized compatibilizer: mechanical and thermal properties

POLYMER INTERNATIONAL, Issue 12 2005
RRN Sailaja
Abstract Lignin was graft copolymerized with methyl methacrylate using manganic pyrophosphate as initiator. This modified lignin was then blended (up to 50 wt%) with low density polyethylene (LDPE) using a small quantity of poly[ethylene- co -(glycidyl methacrylate)] (PEGMA) compatibilizer. The mechanical properties of the blend were substantially improved by using modified lignin in contrast to untreated lignin. Differential scanning calorimetry studies showed loss of crystallinity of the LDPE phase owing to the interaction between the blend components. Thermogravimetric analysis showed higher thermal stability of modified lignin in the domain of blend processing. This suggested that there is scope for useful utilization of lignin, which could also lead to the development of eco-friendly products. Copyright © 2005 Society of Chemical Industry [source]

Improved compatibility of EVOH/LDPE blends by ,-ray irradiation

ADVANCES IN POLYMER TECHNOLOGY, Issue 3 2009
Haihong Li
Abstract The change of compatibility of poly(ethylene- co -vinyl alcohol) (EVOH)/LDPE blends induced by,-ray radiation was studied. Gel extraction experiment results show that the gel fraction of blends increases linearly with the content of LDPE and reaches a maximum at 100 kGy, because neat EVOH is difficult to cross-link by irradiation. A comparison of theoretical and experimental gel contents indicates that some EVOH molecular chains enter the LDPE gel network. The peak at 3363 cm,1 on the Fourier transform infrared spectrum of pure blend gel is assigned to typical stretching of an OH bond, which indicates that a "graft" reaction occurs in the interface between EVOH and LDPE phases during the irradiation process. Mechanical property measurement results support such a structural change. The tensile strength of cross-linked blends increases with absorbed dose first, reaches a maximum value at 150 kGy, and then decreases with dose. A similar trend can also be observed in bending tests. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:192,198, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20160 [source]