Mica filled

Finishing of the filler surfaces may also greatly affect the system viscosity. For mica-filled PP [31] and various thermoplastics filled with calcium carbonate [202, 261] it was shown that the relative viscosity of filled systems was lower than that of systems which contained equivalent quantitied of unfinished filler. Note that in contrast to viscosity in shear, the viscosity in stretching is higher for systems with treated filler [202]. 

Table 17 contains data on the strength of mica-filled PP compositions. 

In order to keep all the advantages of the mica-filled composites it is necessary to so adjust the manufacturing process as to minimize its crushing. Pressing may be the appropriate technique, as it follows from the data of Table 18. 

Table 18. Effect of molding method on mechanical properties of mica-filled thermoplastics (Vf = 0.5) [375]...

Selfdubricating Carbon fibre reinforced Mica-filled ... 

Low Cost Fan Shrouds on Ford F-150, Expedition, Navigator, Ranger are made of PP-5140-F1, a 40% talc polypropylene replacing glass/mica-filled polyamide fan shrouds. 

PE general purpose, ammonia free PE heat resistant, glass fibre reinforced PE impact resistant, cotton filled PE mica filled PerEluoroAlkoxy PolyGlycolic Acid PolyHydroxyAlkanoate PolyHydroxyButyrate... 

It has been suggested that the three-dimensional network structures discussed above, which are believed to occur from particle interactions at high filler loadings, may, in the case of plate-like particles, lead to anisotropic shear yield values [35]. Although this effect has not been substantiated experimentally, further theoretical interpretation of shear yield phenomena in talc- and mica-filled thermoplastics has been attempted [31,35]. 

An ethylene homopolymer (Allied Corporation) was also used as a filler for the IPNs. A 10% addition of this material to the 50/50 urethane/epoxy IPN sample had similar effects as those shown by the 10% mica-filled sample of Figures 7 and 8. A clear difference in this case was a shift of the loss tangent peak to lower frequencies, resulting in a lower tan A value in the frequency range of the display, (see Figure 12). 

The present paper extends Initial work (6) on the modification of mechanical properties in mica-filled PE and PS, and in particular explores the possibility of upgrading the properties of PE/PS blends. These two polymers are Incompatible and are known to form 2-phase systems both in the molten and solid states (9). 

As a first step in this direction, we studied the effect of S monomer pressure and of treatment duration on the properties of 10% mica-filled PS stocks. 

Polypropylene (G/F)/nylon 6,6 Polyurethane open/closed cell foam Polypropylene (mica filled/glass filled/mineral filled) Aluminum tube AA4343/AA3003 base Aluminum tube AA4343/AA3003 base Nylon 6,6/nylon 6/polypropylene Nylon 6,6/nylon 6 Polypropylene (GF)... 

FILMS. Table IV shows data on a five-layer flexible film structure made with mica-filled EVOH, an unfilled-EVOH control and a blend of the two. Approximately a three-fold improvement was measured on the multilayer film structure in good agreement with the previous monolayer data. 

THERMOFORMED CONTAINERS. Table V shows data on a melt-formed, rigid container. This container, together with its unfilled EVOH control, was subjected to a simulated retort cycle at 121°C. The mica-filled container in this example showed an improvement of 2.5 times that of the control. 

In summary, the model systems discussed in this part were zero-shear suspensions of disk-shaped particles in Newtonian liquids, mica-filled polymeric composites, LCPs and colloidal suspensions. The TCP model offers a good understanding of the flow behavior of exfoliated CPNCs. In the case of intercalated systems similar behavior is expected but is complicated by stress-induced changes in the degree of the dispersion and aspect ratio, as well as other possible modifications, such as the thermal decomposition of intercalant. 

Silica (silicon dioxide) particles, synthetic or natural based, have commonly been used in various polymer systems. Silica has a low coefficient of thermal expansion and high stiffness, translating into increased modulus of the compounded polymer. However, silica filler particles are not flake or plate like as talc or mica particles are, and typically have low aspect ratios. This means that unless the particles are very small, a silica filler addition provides a relatively low surface area for contacting the polymer, and thus it reinforces the resin system less than platy fillers. Researchers have also noted that mica-filled PP, for instance, contains fewer voids than silica-filled PP, which helps explain the higher strengths of mica compounds at 20% filler loadings. This tendency to form voids or cavities increases as silica filler content increases [7-20, 7-21). 

Mineral fillers used are calcium carbonate (CaCOj), China Clay (Al/0H [Si.,0 J), miea especially muscovite (KAyOHjFlJAlSijOj J), silica flour (SiO ), talc (Mg, (OH)j[Si Oj J), and wollastonite (CaSiOj). Parameters that need to be considered during inorganic filler selection are basicity, filler impurities that may influence the resin euring proeess, and filler hardness that eauses abrasion of the mold [1]. Mica filled phenolics are used in electrical parts because mica adds outstanding dielectric properties, high thermal and chemical resistance and low water absorption [1]. 

Figure 21.1 Complex dynamic viscosity as a function of shear rate (100 °C, 1 Hz) for the mica-filled NR composites.

Xanthos, M., Faridi, N., and Li, Y. (1998) Processing/structure relationships of mica-filled polyethylene films with low oxygen permeability. Int. Polym. Process.,... 

Unfilled 10-40% talc-filled 1(M0% calcium carbonate- filled 10-30% glass fiber-reinforced 10-50% mica-filled 40% glasefiber-reinf creed... 

Figure 3.34 Tensile strength of 40 wt% mica filled PP effect of PPgAA addition. , 60 NP mica treated with aminosilance HI, 60 S untreated mica. (From Ref, 33.)...

Similar types of results are reported with the use of maleated polypropylenes. In an article by Borden et al. (34), mechanical property improvements of 9-29% are shown with the addition of 10% maleated polypropylene. Another article by Hyche et al. (32) indicated that the use of medium-molecular-weight, highly functionalized PPgMAH works better than high-molecular-weight, low functionalized material in mica filled polypropylene. Chapter 14 provides a detailed discussion of mica reinforcement of polypropylene resins. 

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