Viscoelasticity and flow behavior of irradiation grafted nano-inorganic particle filled polypropylene composites in the melt state

Melt Viscoelasticity of Polyamide 6/Organoclay Nanocomposites

“…At higher frequencies, G'(ω) and G''(ω) started to diverge and to exhibit a frequency dependence (although much weaker than that for the pristine polymer). These data may be considered 8,9 as experimental evidence for the existence of a spatial network of filler particles coated with a polymer boundary layer in the lowfrequency range, and for its plastic yield at higher frequencies for sample 299D. As might have been expected, the viscoelastic behaviour of the sample 299E proved intermediate between those for two other nanocomposites.…”

“…In contrast, no evidence for the Newtonian flow could be detected for nanocomposite 200D with the higher organoclay loading; instead, the complex viscosity | η* | strongly increased, the lower the frequency (Figure 3). This behaviour suggests the occurrence of plastic yield of an infinite cluster of nanoparticles coated with BI, preceding the macroscopic melt flow 8,9 . As before, the sample 299E exhibited an intermediate behaviour.…”

“…The patterns of the relaxation times spectra for nanocomposites with moderate filler loadings (i.e., samples 299F and 299E) were similar, except the decays of η (τ) shifted to significantly longer relaxation times τ 1 (Figure 4). A completely different pattern of the relaxation time spectrum for the nanocomposite 299D (especially, the absence of decay at the longest relaxation times), was further evidence 8,9 for a shear-resistant, spatial structure ("infinite cluster" 16 ) of clay nanoparticles coated with BI in the melt phase of PA6.…”

“…The processability of nanocomposites, however, can present some problems, in view of the extreme sensitivity of melt flow behaviour to the aspect ratio of clay nanoparticles 4 and to the quality of their dispersion (exfoliation) [4][5][6][7] . Moreover, viscoelastic studies of irradiation-grafted nano-inorganic particlefilled polypropylene composites in the melt state 8,9 revealed the onset of a plastic yield phenomenon for a nanocomposite with the filler volume content as low as 4.68% . This was regarded as experimental evidence for the shear-resistant, infinite cluster of nanoparticles coated with a polymer boundary interphase (BI) when the ratio of the mean thickness of the polymer interlayer between neighbouring nanoparticles, <L> , to the mean radius of gyration of a polymer coil, <R g > , approached the "critical" value, <L>/<R g > ≈ 1.…”

Effect of immobilized interfacial layer on the maximum filler loading of polystyrene/silica nanocomposites

“…This is closely related to the specific surface area of nanoparticles, this idea is in agreement with the Privalko. 15 The experimentally dynamic moduli of polystyrene/ silica nanocomposites having different silica particles are presented in Figure 7. When the filler volume …”