Blending law for binary blends of fractions of linear polystyrene

Montfort, J. P.; Marin, G.; Arman, J.; Monge, Ph.

doi:10.1016/0032-3861(78)90221-5

Cited by 57 publications

(33 citation statements)

References 9 publications

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“…It is known that for polymeric materials with Mw larger than a critical value Me, a plot of the zero-shear viscosity t/o vs. M w usually conforms to the equation: (17,18) in the text…”

Section: Influence Of M~ and M W D O N Qo And %mentioning

confidence: 96%

“…The experimental parameter Zo is essentially an average relaxation time, characteristic of the low frequency region and is closely related [17] to the maximum relaxation time of the Rouse theory [18], applied to an undiluted polymer [19]. It was observed that variations of z o and ~/o with temperature are similar [20]; moreover the molecular weight dependence of z o is well represented by a power-law equation with an exponent about 3.5, for samples of very narrow MWD, while the exponent is larger for polydisperse samples [12,20].…”

Section: Influence Of M~ and M W D O N Qo And %mentioning

confidence: 99%

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An investigation of the viscoelastic properties of molten polypropylene

Ottani¹,

Pezzin

Castellari

1988

Rheol Acta

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Two series of polypropylene samples of different molecular weight, the first obtained directly from polymerization reactions and the second from controlled thermal degradation, were studied by dynamic testing in the melt state. Several viscoelastic parameters were determined, and correlated with weight-average molecular weight Mw. It is found that the Mw-dependence of the two series is rather different.

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“…It is known that for polymeric materials with Mw larger than a critical value Me, a plot of the zero-shear viscosity t/o vs. M w usually conforms to the equation: (17,18) in the text…”

Section: Influence Of M~ and M W D O N Qo And %mentioning

confidence: 96%

Section: Influence Of M~ and M W D O N Qo And %mentioning

confidence: 99%

An investigation of the viscoelastic properties of molten polypropylene

Ottani¹,

Pezzin

Castellari

1988

Rheol Acta

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“…Indeed, polydisperse linear polymers, like branched ones, are characterised by a pronounced elastic and pseudoplastic character [93][94][95][96][97][98][99][100][101][102][103]. Correlations between molecular structure and rheological behaviour have been analysed in bimodal blends of well-defined substances such as PS and PB [104][105][106][107][108][109][110]. Some studies have shown a slight increase in viscosity and E a with the polydispersity index in supposedly homogeneous linear LLDPE blends [111].…”

Section: Model Polymersmentioning

confidence: 99%

Effect of long chain branching on linear-viscoelastic melt properties of polyolefins

et al. 2002

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Abstract:The aim of this review is to provide evidence that rheological testing is a potent tool for characterising polymers in the melt. An effort has been made in order to gather results in conventional and model polyolefins, and correlating them with phenomena occurring at the molecular level. We have focused our interest on long chain branching (LCB). In the case of materials containing long side-chain branches, strong effects on viscosity, elastic character and activation energy of flow are general features. Literature results mostly indicate that the effect of polydispersity on these parameters could be very similar to that expected due to the presence of LCB -notwithstanding that the effects of LCB seem to be stronger than those due to polydispersity for a given molecular weight. Different relaxation processes appear as a consequence of the presence of LCB: slower terminal relaxation behaviour than of linear counterparts, and faster additional branch relaxation at higher frequencies, clearly distinguishable from polydispersity effects. To measure the amount of LCB from limited viscoelastic data and molecular properties seems to be a suitable instrument to explain the rheological features of the different polymers, but it fails when the results are compared with measured values of LCB density in model polymers. The actual framework leads us to say that the number of branches is less important than the topology itself. Therefore, the position and architecture of the branches along the polymer main chain are the main factors that control the rheology of the material.

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“…It can be seen in these figures that the predicted dependence of G' on blend composition in log G'-logG" plots agrees remarkably well with the experimental results given in Figures 11,15, and 19. It should be mentioned that in constructing Figures 38 to 40, we had to extrapolate the data of Struglinski21 to the low-frequency range, following the procedure described by Montfort et al 14 In the theoretical predictions presented in Figures 38 to 40, the value of p was set equal to 10 and then the average relaxation time, T,, was calculated with the relationship T~ = q,, J,", using the following numerical values: 22 (a) For 41L at 25"C, …”

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confidence: 99%

Influence of molecular weight distribution on the linear viscoelastic properties of polymer blends

Han¹

1988

J of Applied Polymer Sci

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SynopsisLiterature data for the dynamic viscoelastic properties of binary blends of nearly monodisperse polybutadienes, polystyrenes, and poly(methy1 methacry1ate)s was analyzed using logarithmic plots of dynamic storage modulus G' versus loss modulus G", based on a recent theoretical study by Han and Jhon.% It has been found that for binary blends of monodisperse polymers with molecular weights M much greater than the entanglement molecular weight Me, the value of G' in log G'-log G" plots becomes independent of molecular weight, increases sharply as small amounts of a high-molecular-weight component are added to a low-molecular-weight component, and passes through a maximum G,!,,,, at a critical blend composition (C$2)mm, and that G,!,,,, becomes larger and (C$2)m,, becomes smaller as the ratio of component molecular weights increases. However, as the molecular weight distribution of the constituent components becomes broader, the effect of blend composition on G' in log G'-log G" plots becomes less pronounced. This observation has enabled us to explain why log G'-log G" plots of binary blends of commercial polymers, namely, blends of two low-density polyethylenes, blends of poly( c-caprolactone) and poly(styrene-co-acrylonitrile), and blends of poly(methy1 methacrylate) and poly(viny1idene fluorids), all having broad molecular weight distributions, give rise to values of G' between those of the constituent components. When one of the constituent components has molecular weight smaller than Me, while the other has molecular weight larger, and as small amounts of the high-molecular-weight component are added to the low-molecular-weight component, log G'-log G" plots of binary blends give rise to values of G' larger than those of the constituent components a t low values of G", but approaches the value of G' for the low-molecular-weight component as the value of G" is increased. However, as the amount of the high-molecular-weight component is increased above a certain critical composition, binary blends give rise to values of

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Blending law for binary blends of fractions of linear polystyrene

Cited by 57 publications

References 9 publications

An investigation of the viscoelastic properties of molten polypropylene

An investigation of the viscoelastic properties of molten polypropylene

Effect of long chain branching on linear-viscoelastic melt properties of polyolefins

Influence of molecular weight distribution on the linear viscoelastic properties of polymer blends

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