Filler weight fraction

Tang and co-workers [150], found that the tensile modulus of propylene-vinyl acetate copolymer increased with an increased filler weight fraction and the impact strength... 

OM Modified filler density (gcirr ) Filler weight fraction (%) Composite density (gem )... 

Modification Modified filler density Filler weight fraction Composite density... 

Figure 30. Weight losses as a function of temperature for pure PA-12 fibres and PA-12 nanocomposite fibres containing various filler weight fractions of carbon nanofibres (CNF)...

Plots summarising the relationship between (a) tensile modulus and (b) yield stress of melt-spun polyamide-12 nanocomposites and nanoscale filler weight fraction for CNFs, arc-grown (aMWCNT) entangled (eMWCNT) and aligned (aMWCNT) multiwall structures. (Tensile tests were based on a constant force ramp. )... 

Interfacial structure is known to be different from bulk structure, and in polymers filled with nanofillers possessing extremely high specific surface areas, most of the polymers is present near the interface, in spite of the small weight fraction of filler. This is one of the reasons why the nature of the reinforcement is different in nanocomposites and is manifested even at very low filler loadings (<10 wt%). Crucial parameters in determining the effect of fillers on the properties of composites are filler size, shape, aspect ratio, and filler-matrix interactions [2-5]. In the case of nanocomposites, the properties of the material are more tied to the interface. Thus, the control and manipulation of microstructural evolution is essential for the growth of a strong polymer-filler interface in such nanocomposites. 

Percentage filler or ratio of fillers Uniformity (content and weight) Fractional factorial... 

It is known, that physical and mechanical properties of carbonic composites on the base of this polymer (UPA 6-15,. .., UPA 6-40), where carbon fibrous materials Ural and Viskum are applied as a filler, depend on its weight fraction and uniformity of the filler distribution in the composite. 

The volume fraction of the fillers in the compound depends on its specific gravity. A higher weight fraction of heavier fillers such as bronze can be incorporated than lighter additives like glass. Physical properties of the compound deteriorate with increase in the volume fiaction of the filler as illustrated in Fig. 3.4. 

Adhesion interactions at the solids/polymers interfaces are first and foremost adsorption interactions between the sofid surface and polymer molecules [1—11]. After polymerization there is a low molecular-weight fraction of coupling agents, which can decrease the cohesion and adhesion of the polymer film. If the molecules from this fraction interact with the filler particles preferentially (which can be reached due to the filler surface modification) instead of with the material surface covered, then the boundary layer of the film can be free from this fraction and adhesion increases as strengthening the boundary layer of the coating leads to stronger adhesion of the coating to the covered surfaces [46]. 

As stated previously, styrene-diene triblock copolymers are the most important category of thermoplastic elastomers. Unlike most other TPEs, they can be blended with large quantities of additives without a drastic effect on properties. In almost all applications, the actual triblock copolymer content is less than 50%. Oils are used as a processing aid and do not result in a significant loss of properties if the polystyrene domains are not plasticized. For this reason, naphthalenic oils are preferred. The use of inert fillers such as clays or chalks reduces the cost of the final material. Unlike conventional rubbers, inert fillers do not have a substantial effect on the mechanical properties of TPEs. Thermoplastics such as polyethylene or polypropylene are also used to improve the solvent resistance and can increase the upper service temperature. Polystyrene homopolymer is used as a processing aid, which also increases the hard phase weight fraction and causes the material to stiffen. 

Suwanprateeb and Hatthapanit [6] compared the use of black rice husk ash based silica as a filler in epoxy resins used for embedding electrical and electronic devices to the use of two commercial fillers, fused silica and crystalline silica, at different weight fractions between 20-60%. Increased mixing viscosity, thermal expansion... 

Tables 8.2 and 8.3 show the densities of the fillers after treatment with various surface modifications. The filler density decreased significantly from 2.6 gcm value for the inorganic filler after surface modification. Weight fraction of the filler corresponding to 3.5 vol% inorganic filler fraction is also reported. Densities of the nanocomposites are also reported in these tables, which also indicate that the incorporation of filler did not increase their buUdness. The composite densities lie in the range of 1.20 to 1.23gcm" as compared to l.lSgcm" for pure epoxy.

A typical SMC contains about 30-50% of fiber (25-75 mm long, frequently E-glass fiber 25.4 mm), 25% resin (usually unsaturated polyester), and 25-45% filler (usually, calcium carbonate, alumina or clay) by the weight fraction. In the case of structural applications, 50-70 wt% of fibers can be used in SMCs. In general, fillers are not added if the SMC contains more than 60 wt% of fiber (see Table 3.1, Mallick, 1990). 

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