Dispersion of fibres

Fig. 3.8 Dispersion of fibres in cross-section of unidirectionaJ composite...

Fig. 11. Typical flow curves of dispersions of fibre-forming particles in a Newtonian liquid. The arrow indicates the direction in which the filler concentration increases...

Dispersing of fibres (and filler) and mixing with chemical additives... 

The amount of fibres in a cement matrix may vary from 0.1% to 0.9% of mass of cement (Rafiqul Islam and Khorshed Alam 1987 Singh 1987). The dispersion of fibre properties is usually rather large because of natural variations in the plant population and simple production techniques also increase the variability of composite material properties. 

The non-fibrous components are first mixed together and the fibrous materials are then added. The properties of components are critically dependent on the mixing procedures since these will affect dispersion and fibre degradation. 

As it was established by Geus et a/.[18, 19] the decrease of the rate of carbon deposition is a positive factor for the growth of fibres on metal catalysts. Si02 is an inhibitor of carbon condensation as was shown in Ref [20]. This support also provides possibilities for the stabilization of metal dispersion. Co and Fe, i.e. the metals that give the best results for the tubular condensation of carbon on graphite support, were introduced on the surface of siUca gel... 

The effects of dispersion and birefringence on stellar interferometry will be discussed in Sections 17.2.3 and 17.2.4. New kind of fibres has been design to manage the dispersion properties using a silica / air structure. These fibres, so called Photonic Crystal Fibres, are very promising for many applications (Peyrilloux et al., 2002). 

The SKN18 glass for henzil crystal cored fibre has chromatic dispersion of 0.018 in the 0.532ym to 1.06l+um wavelength range and this is sufficient for the SH to couple into the radiation field. The SH radiation in this case exits from the fibre core at an angle, a, given by... 

An aqueous dispersion of a disperse dye contains an equilibrium distribution of solid dye particles of various sizes. Dyeing takes place from a saturated solution, which is maintained in this state by the presence of undissolved particles of dye. As dyeing proceeds, the smallest insoluble particles dissolve at a rate appropriate to maintain this saturated solution. Only the smallest moieties present, single molecules and dimers, are capable of becoming absorbed by cellulose acetate or polyester fibres. A recent study of three representative Cl Disperse dyes, namely the nitrodiphenylamine Yellow 42 (3.49), the monoazo Red 118 (3.50) and the anthraquinone Violet 26 (3.51), demonstrated that aggregation of dye molecules dissolved in aqueous surfactant solutions does not proceed beyond dimerisation. The proportion present as dimers reached a maximum at a surfactant dye molar ratio of 2 5 for all three dyes, implying the formation of mixed dye-surfactant micelles [52]. 

PREPARATION OF WASTE PAPER FOR PAPER MAKING Dispersion of the Fibres... 

It is common during the dispersion process to use sodium hydroxide as this assists in ink removal and also in the more efficient dispersion of papers which have been chemically sized (see Chapter 7). Sodium hydroxide also has a swelling effect on cellulosic fibres and it is most probable that this too has a beneficial effect on strength. 

This product therefore solved more important problems than the original target, since it improved the washability and resistance to electrostatic charge development of polyester fabrics. It was marketed first by ICI in Europe as Permalose and in the USA as Milease other companies produced similar products. Moreover, aqueous dispersions of this type of surface-active agent proved useful as rinse additives for washing hydrophobic fibres in general and became ingredients of consumer-oriented products. 

Mahlberg etal. (2001) studied the effect of acetylation of wood fibres (20 % WPG) upon the mechanical properties of wood fibre PP fibre composites, with and without the addition of a novalak PF. Acetylation resulted in significant improvements in MOR, MOE and IBS in a composite containing 20 % by weight of PP fibre. With a combination of PF and PP (both 10 % by weight) and acetylated wood fibre, MOR was unchanged, MOE decreased and only IBS showed a significant improvement. Acetylation also contributed to a better dispersion of the wood fibres in the PP matrix. 

More recent studies continue to support the unique antifibrillatory activity of bretylium. Kowey et al. [38] have shown that bretylium prevented spontaneous VF and decreased the effects on VF threshold in a feline myocardial infarction model. They attributed this beneficial effect to a decrease in the dispersion of refractoriness between normal and ischaemic regions of the heart. In contrast, clofilium (14, see below), which had little effect on dispersion of refractoriness after coronary occlusion, was unable to prevent spontaneous VF. Similar results were seen in isolated tissue studies with canine subendocardial Purkinje fibres and ventricular muscle which contained both normal and ischaemic regions [39]. In these studies bretylium caused a smaller increase in dispersion of refractoriness in subendocardial Purkinje fibres than either sotalol or clofilium. In ventricular muscle tissue, bretylium decreased dispersion while sotalol and clofilium increased dispersion of refractoriness. 

Researchers have been dogged by the inability to delineate between myoactivity and neuroactivity, mainly because the isolation of individual tissues by dissection is extremely difficult. This obstruction precipitated the development of methods to generate dispersed muscle fibres, and these preparations provided the first visual information on individual muscle fibres and/or muscle fibre bundles three morphologically distinct fibre types were recorded from Schistosoma mansoni, frayed, spindle-shaped and crescent-shaped fibres (Day et al., 1993). Although the location of all three fibre types within the worm is not clear, it has been suggested that the frayed fibres originate from the longitudinal muscle layer. 

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