Rheology of concentrated suspensions containing mixtures of spheres and fibres

Marti, Irene; Höfler, Oliver; Fischer, Peter; Windhab, Erich J.

doi:10.1007/s00397-005-0432-9

Cited by 62 publications

(48 citation statements)

References 27 publications

(39 reference statements)

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“…aspect ratio of unity) and fibres of varying degrees of alignment. The results are relevant to understanding rheological [24] and phase behaviour [25][26][27][28][29], as well as computer simulation studies [30][31][32][33] of rod-sphere mixtures. The experimental relevance of such work is demonstrated in a recent paper by Sumfleth et al [34], who found that for an conductive epoxy nanocomposite, a considerable amount of multi-wall carbon nanotubes (MWCNTs) can be replaced by carbon black (CB) without changing the electrical properties.…”

Section: Introductionmentioning

confidence: 95%

Modelling percolation in fibre and sphere mixtures: Routes to more efficient network formation

Rahatekar

Shaffer

Elliott

2010

Composites Science and Technology

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Section: Introductionmentioning

confidence: 95%

Modelling percolation in fibre and sphere mixtures: Routes to more efficient network formation

Rahatekar

Shaffer

Elliott

2010

Composites Science and Technology

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“…This line of reasoning was applied to a range of particle sizes and relative viscosities of trimodal, tetramodal, octamodal and infinite modal suspensions were calculated. This Farris model has also been successfully applied to binary suspensions of glass rods and fibres (Marti et al 2005), indicating the applicability of this model to mixtures of particles from different shape classes. Do et al (2007) showed that the apparent viscosity and textural attributes such as melting behaviour of low fat chocolate (22% fat) can be improved by optimising the proportion fine and coarse sugar in the formulation.…”

Section: Effect Of Particle Size Distributionmentioning

confidence: 91%

“…As the aspect ratio of the particle is increased, the relative viscosity increases with increasing concentration. Particles with higher aspect ratios (glass fibres) reach maximum viscosity at lower concentration compared to spheres (Marti et al 2005) as shown in Figure 2.6. This is because particles with higher aspect ratios occupy a higher a hydrodynamic volume which has a greater impact on the flow field resulting in higher viscosities at lower concentrations.…”

Section: Effect Of Particle Morphologymentioning

confidence: 96%

“…Small changes in particle size distribution has significant effects on the relative motion of particles during flow (Metzner 1985). Suspensions with wider particle size distributions have higher maximum packing fractions as smaller particle are able to fit between the gaps of larger particles (Barnes, Hutton & Walters 1989;Marti et al 2005). Smaller particles can also acts as lubricants, as during shear, large particles flow over smaller particles decreasing the viscosity of the system (Servais, Jones & Roberts 2002).…”

Section: Effect Of Particle Size Distributionmentioning

confidence: 99%

“…He was one of the first investigators to consider the contribution of fine and coarse particles individually (Farris 1968). According to the Farris model the coarse particles were suspended in a matrix of fine particles with the two fractions behaving independently of each other (Marti et al 2005). Initially the relative viscosity of the fine particle suspension was calculated η rf = η f /η 0 where η f is the viscosity of the suspension containing fine particles and η 0 is the viscosity of the liquid.…”

Section: Effect Of Particle Size Distributionmentioning

confidence: 99%

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Insights into rational design of plant based foods to improve management of dysphagia

Tobin¹

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Normal swallowing is a complex process which requires sufficient mastication and lubrication of the food to transport the bolus from the mouth to the pharynx. In people suffering from dysphagia this process is not well coordinated and they often have difficulty in transporting food and water from the mouth to the stomach, which can lead to choking or aspiration. Modification of food texture by mincing or pureeing normal food is used to prevent these complications; however inconsistencies in texture can affect the consumption of these foods. Hence, malnutrition, dehydration and aspiration pneumonia, are a common problem with dysphagia sufferers.Using green peas as a model food system, this project investigated the effect of three method of comminution -mincing, pureeing and freeze-fracturing (processing whilst frozen) -on the macro and microstructure of the peas and its impact on rheological behaviour and sensory perception.Comminution of peas resulted in a particulated soft solid with hierarchical structures with broad range of particle sizes and shapes i.e. from large clusters of cells (5 mm) to starch granules (10 µm) which were released from broken cells. These pea particles were suspended in serum released during cellular structure breakdown. The high concentration, broad particle size distributions, variations in morphology and deformability of particles made this system complex and challenging to measure. Vane geometry was used to evaluate the rheological behaviour of comminuted peas, as it enabled accurate measurement of dispersions containing large particles without altering the product structure and it also eliminated any wall slip effects. The effect of pea variety, particle size distribution and amount of serum or added water on rheological behaviour was studied.Results demonstrated that comminuted peas were characteristically solid-like with higher elastic than viscous modulus (G´ > G˝). They also exhibited a yield stress which is an important parameter in these systems as it is a good indicator of the amount of effort required to initiate flow during oral processing. Minced peas with over 50% of the particle >1 mm in size had broader size distribution, which packed better than narrower distributions of pureed peas, resulting in higher G´ and yield stress. Changing the particle size distributions by systemically increasing the percentage of minced peas in a mince/puree blend also increased G´ and yield stress. This indicated that particle size distribution can be used to modify flow behaviour, while keeping the solids content the same.Diluting minced and pureed peas with incremental amounts of water showed that in such concentrated systems, small changes in solid to liquid ratio had a considerable impact on G´ and yield stress, as small increments in the liquid phase decreased G´ and yield stress dramatically. The variety of pea did not impact on the particle size distribution, but it affected the amount of serum released and particle firmness. These findings showed that particle concentratio...

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Understanding which parameters control shallow ascent of silicic effusive magma

Thomas

Neuberg

2014

Geochem Geophys Geosyst

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The estimation of the magma ascent rate is key to predicting volcanic activity and relies on the understanding of how strongly the ascent rate is controlled by different magmatic parameters. Linking potential changes of such parameters to monitoring data is an essential step to be able to use these data as a predictive tool. We present the results of a suite of conduit flow models Soufriè re that assess the influence of individual model parameters such as the magmatic water content, temperature or bulk magma composition on the magma flow in the conduit during an extrusive dome eruption. By systematically varying these parameters we assess their relative importance to changes in ascent rate. We show that variability in the rate of low frequency seismicity, assumed to correlate directly with the rate of magma movement, can be used as an indicator for changes in ascent rate and, therefore, eruptive activity. The results indicate that conduit diameter and excess pressure in the magma chamber are amongst the dominant controlling variables, but the single most important parameter is the volatile content (assumed as only water). Modeling this parameter in the range of reported values causes changes in the calculated ascent velocities of up to 800%.

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Rheology of concentrated suspensions containing mixtures of spheres and fibres

Cited by 62 publications

References 27 publications

Modelling percolation in fibre and sphere mixtures: Routes to more efficient network formation

Modelling percolation in fibre and sphere mixtures: Routes to more efficient network formation

Insights into rational design of plant based foods to improve management of dysphagia

Understanding which parameters control shallow ascent of silicic effusive magma

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