Uniaxial elongational flow effects and morphology development in LDPE/phosphate glass hybrids

Shear and elongational viscosity measurements were performed on low-density polyethylene/phosphate glass (LDPE/Pglass) hybrid materials in the liquid state. Under shear deformation, the hybrids with low concentrations of Pglass showed a Newtonian region at low frequencies, followed by shear-thinning...

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Bibliographic Details
Published in:Rheologica acta 2007-08, Vol.46 (7), p.989-1001
Main Authors: URMAN, Kevin, SCHWEIZER, Thomas, OTAIGBE, Joshua U
Format: Article
Language:English
Subjects:
Applied sciences
Composites
Elongation
Exact sciences and technology
Forms of application and semi-finished materials
Low concentrations
Low density polyethylenes
Morphology
Phosphate glass
Polymer industry, paints, wood
Rheological properties
Shear deformation
Shear thinning (liquids)
Technology of polymers
Viscosity
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Summary:Shear and elongational viscosity measurements were performed on low-density polyethylene/phosphate glass (LDPE/Pglass) hybrid materials in the liquid state. Under shear deformation, the hybrids with low concentrations of Pglass showed a Newtonian region at low frequencies, followed by shear-thinning behavior at high frequencies. High Pglass concentrations displayed shear-thinning behavior over the whole range of frequencies studied. Deviations from the log-additivity rule for viscosity were found to be compositionally dependent and generally indicated an immiscible mixture. The elongational viscosity of the hybrids increased at very low Pglass concentrations (1–2 vol.% Pglass) and then was drastically reduced at higher concentrations (i.e., >10 vol.% Pglass). In addition, elongational flow was found to induce the formation of Pglass fibrils in hybrids containing at least 10 vol.% Pglass. This was correlated to the elongational capillary number; the critical elongational capillary number was estimated to be 0.22. The elongational deformation was also found to greatly increase the overall crystallinity of the system due to molecular orientation of the LDPE polymer chains as confirmed by wide angle X-ray diffraction. A critical composition of 5 vol.% Pglass was found to be the point at which LDPE hybrid rheological properties, molecular orientation, and morphology changed drastically.
ISSN:0035-4511
1435-1528
DOI:10.1007/s00397-007-0184-9