Fillers discrete particles

Hydrous kaolins, standard GCC, rhombohedral PCC, talc and titanium dioxide may be considered products that comprise discrete particles. These filler products typically range from plates to spheres to blocks of varying uniformity. 

Extension of fibre with filler almost always results in reduced drying demands, as minerals do not absorb water compared to fibre. However, aggregated fillers with very high surface area and internal void volume may result in a wetter web going to the press section. Figure 6.18 shows a comparison between scalenohedral PCC and GCC filler in press solids. Discrete particles, like GCC, typically drain more quickly compared to similarly sized aggregated particles, like scalenohedral PCC. 

Three carbon-plastic compositions were also included as materials for investigation. These compositions were molded by commercial plastic forming techniques. The PTFE and nylon had carbonaceous fillers present as discrete particles in the plastic matrix. The third type of material had continuous phases of both graphitic carbon and plastic (phenol-furfural),... 

The term filler in the present context is used for describing those inert, solid materials which are physically dispersed in the pol3mtier matrix, without significantly affecting the molecular structure of the polymer. Further, the term is restricted to those materials which are in the form of discrete particles or of fibers not exceeding a few inches in length. Continuous filaments or fabrics either woven or nonwoven are not included in this category of fillers discussed... 

The general types of behavior predicted for systems following equations 20.1, 20.2 and 20.3 are compared in Figure 20.3. The Young s modulus of the filler in Equation 20.1 was assumed to be 100 times that of the matrix and calculations were performed for Af=10, Af=100 and Af=1000 to compare the effects of discrete filler particles with differing levels of anisotropy. It was assumed that E(hard phase)=100, pc=0.156 and (3=1.8 in Equation 20.2. For simplicity, it... 

The particles of carbon black are not discrete but are fused clusters of individual particles. The reinforcement conferred by the black is not influenced to any extent by the size of the unit but predominantly by the size of the particles within the unit. The primary particle typically has cross-sectional dimensions" of 5-100 nm. It is well established that the most appropriate way of describing the size of the primary particles is to express it as speciflc surface area/weight Particle size of itself has relatively little effect on the modulus. But tensile and tear strengths are affected by the particle size and both properties are normally enhanced as the surface area increases (i.e. surface area increases with decreasing particle size). The high surface area enhances the ability of the filler to wet the rubber and thus enhances the interaction at the rubber filler interface. It is the enhancement of the filler-rubber interface that provides the desired reinforcement in filled vulcanized rubber. 

Hence PPE/PA alloys have the polyamide as the continuous phase for good chemical resistance and processability. The discrete phase consists of finely dispersed particles of PPE. The PPE acts as an organic filler which lowers moisture uptake, increases properties at elevated... 

The 5-ifitrosothiols are generally formed by reaction of nitrous acid with the parent thiol and are reported to require copper-mediated decomposition, reaction with ascorbate, or cleavage by light to release NO. NO donors are incorporated into materials either by blending discrete NO donors within polymeric films or covalently attached to polymer backbones and/or to the inorganic polymeric filler particles that are often employed to enhance the strength of biomedical polymers (e.g., fumed silica or titanium dioxide). ... 

The morphologies of PCC used as fillers are commonly scalenohedral (rosetteshaped), rhombohedral (cubic-shaped) or aragonite (needle-shaped). The type of morphology is defined by process parameters Kke temperature, pressure, reaction speed, additives etc. The particles can be arranged as individual discrete, clustered or agglomerated. These different arrangements represent an additional tool to influence the overall pigment performance. 

A more advanced averaging, called the weighted discretization (WD), was proposed by Filler [116]. It modifies both the susceptibility and the self-term of the boundary dipoles. The particle surface, crossing the subvolume F,, is assumed linear and divides the subvolume into two parts the principal volume that contains the center and a secondary volume F/ with susceptibilities xf, xf and electric fields Ef = E/, Ef, respectively. Electric fields are considered constant inside each part and related to each other via a boundary condition tensor T, ... 

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