Linear low-density polyethylene/silica micro- and nanocomposites: dynamic rheological measurements and modelling

Abstract. Polyether-block-amide (PEBA) /clay nanocomposites were prepared water-assisted by twin-screw extrusion. Both organomodified and pristine (i.e. purified but non-modified) montmorillonite clays were used. A high-pressure differential scanning calorimetry analysis carried out in the processing conditions demonstrated that PEBA/water blend exhibits some miscibility and that amide blocks and water behave as a single phase. In addition to a significant decrease of the melting temperature, water injected into the melt plays a key role among the filler dispersion and prevents the matrix from degradation during melt-extrusion. This process enables the compounding of pristine clay-based nanocomposites whose dispersion state is high enough for the resulting mechanical performances in tension to be at least equivalent to what is reached with organomodified clay. Effects of the nanofiller dispersion onto the macromolecules' mobility are detailed and fracture mechanisms are identified for the various structures.

Section: Rheologysupporting

confidence: 77%

Efficient one-step melt-compounding of copolyetheramide/pristine clay nanocomposites using water-injection as intercalating/exfoliating aid

Touchaleaume¹,

Soulestin²,

Sclavons³

et al. 2011

“…On the other hand, La Mantia et al [30] found that organomodified layered silicates did not have any effect on the crystallization properties of LLDPE fibers and hypothesized that the orientation in both crystalline and amorphous phases were similar for filled and unfilled fibers. According to our previous works on polyethylene based nanocomposites [20,21,23], we can hypothesize that the limited influence played by fumed silica nanoparticles on the crystallization properties of our HDPE matrix could be probably ascribed to their dispersion state. However, further investigations are needed to reach a deeper comprehension on the role played by nanosilica on the crystallization behaviour of polyethylene.…”

Section: Results and Discussion 31 Dsc And Dmta Resultsmentioning

confidence: 99%

“…The effect of silica and zirconia nanoparticles on the microstructure of LLDPE nanocomposites synthesized via in situ polymerization with zirconocene was investigated by Jongsomjit et al [17], while Wang et al [18] analyzed the dispersion behaviour of titania (TiO 2 ) nanoparticles in polyolefin nanocomposites. In recent years an extended investigation was carried out by this research group on the viscoelastic and the fracture behavior of polyolefin based nanocomposites [19][20][21][22][23]. It was found that the addition of small quantities of fumed silica nanoparticles could substantially improve both the failure properties and the creep stability of the investigated matrices.…”

Section: Introductionmentioning

confidence: 99%

High performance polyethylene nanocomposite fibers

D’Amato¹,

Dorigato²,

Fambri³

et al. 2012

Self Cite

Abstract.A high density polyethylene (HDPE) matrix was melt compounded with 2 vol% of dimethyldichlorosilane treated fumed silica nanoparticles. Nanocomposite fibers were prepared by melt spinning through a co-rotating twin screw extruder and drawing at 125°C in air. Thermo-mechanical and morphological properties of the resulting fibers were then investigated. The introduction of nanosilica improved the drawability of the fibers, allowing the achievement of higher draw ratios with respect to the neat matrix. The elastic modulus and creep stability of the fibers were remarkably improved upon nanofiller addition, with a retention of the pristine tensile properties at break. Transmission electronic microscope (TEM) images evidenced that the original morphology of the silica aggregates was disrupted by the applied drawing.

“…An increase of the nanofiller amount promotes a reduction of the cell size and a consequent increase of the cell density, while opposite effects can be obtained increasing the foaming pressure. A quantitative evaluation of the cell size distribution was performed by using ImageJ software (U. S. National Institutes of Health, Bethesda, Maryland, USA) [44].…”

Section: Results and Discussion 31 Morphologymentioning

confidence: 99%

Mechanical behaviour of cyclic olefin copolymer/exfoliated graphite nanoplatelets nanocomposites foamed through supercritical carbon dioxide

Biani¹,

Dorigato²,

Bonani³

et al. 2016

Self Cite

Abstract.A cycloolefin copolymer matrix was melt mixed with exfoliated graphite nanoplatelets (xGnP) and the resulting nanocomposites were foamed by supercritical carbon dioxide. The density of the obtained foams decreased with the foaming pressure. Moreover, xGnP limited the cell growth during the expansion process thus reducing the cell diameter (from 1.08 to 0.22 mm with an XGnP amount of 10 wt% at 150 bar) and increasing the cell density (from 12 to 45 cells/mm 2 with a nanofiller content of 10 wt% at 150 bar). Electron microscopy observations of foams evidenced exfoliation and orientation of the nanoplatelets along the cell walls. Quasi-static compressive tests and tensile creep tests on foams clearly indicated that xGnP improved the modulus (up to a factor of 10 for a xGnP content of 10 wt%) and the creep stability.