Talc-filled properties

The layers in the plate-like structure of talc are Joined by very weak van der Waals forces, and therefore delamination at low shear stress is produced. The plate-like structure provides high resistivity, and low gas permeability to talc-filled polymers. Furthermore, talc has several other structure-related unique properties low abrasiveness, lubricating effect, and hydrophobic character. Hydrophobicity can be increased by surface coating with zinc stearate. 

Polyolefins are well adapted to the mono-material concept talc-filled polypropylene and LFRT for structural parts, foamed polyethylene and polypropylene for damping, polypropy-lene/EPDM alloys or copolymers for skins. Some other functions need incompatible polymers with specific characteristics such as optical properties. Without claiming to be exhaustive, the other thermoplastic materials are ... 

Numerous filler characteristics influence the properties of composites [14,15]. Chemical composition and, in particular, purity of the filler both have a direct and an indirect effect on its application possibilities and performance. Traces of heavy-metal contamination decrease stability. Insufficient purity leads to discoloration, high purity CaC03 has the advantage of a white color, while the grey shade of talc filled composites excludes them from some fields of application. 

Its plate-like structure provides talc-filled materials with important properties, such as, high resistivity and low gas permeability. This comes about because the diffusion path is so complicated. Several other unique properties of talc are structure-related, including its lubricating effect, caused by its easy delamination its low abrasiveness, because talc is the softest mineral in the Mohs hardness scale and the hydrophobic properties of its surface. Hydrophobicity can be increased even more by surface coating with zinc stearate. Figure 2.63 shows the plate-like structure of talc. 

Also, the proportion of fibers in the skin (or shell) and those in the core depends on the rates of fiow." Low injection rates and low temperatures causes an expansion of the shell (skin) region These relationships also affect the orientation of polymer chains in filled and unfilled polymers during proc-essing Orientation of fiber in blow molding of bottles filled with fibers caused anisotropy of properties. Tensile strength was increased in the machine direction. At the same time, talc filled bottles had more uniform tensile properties than unfilled bottles. ... 

Gahleitner et al. (1994) describe the rheology of talc-filled PP. They note the effects of filler concentration, particle size and dispersion on linear viscoelastic properties. 

Murthy, N. S., et al., "Structure and Properties of Talc-Filled Polyethylene and Nylon 6 Films," Journal of Applied Poly. Science, 31, 2569-2582 (1986). 

The following properties of Biodac -filled LDPE can be considered advantageous compared to those of CaCOs- or talc-filled LDPE ... 

BYK s P 4101 coated-silicon dioxide compatibilizer reportedly increases the mechanical properties of 40% talc-filled PP homopolymer, for example, while still reducing screw torque and pressure [11-11]. 

Hattotuwa, G.B. Premalal Ismail, H. Baharin, A. (2002). Comparison of the Mechanical Properties of Rice Husk Powder Filled Polypropylene Composites with Talc Filled Polypropylene Composites. Polymer Testing, Vol.21, No.7, (n. d. 2002), p>p. 833-839, ISSN 0142-9418... 

Table 3 provides average properties for the polypropylene with 40 % talc filled. 

Sekelik, R. J., Stepanov, E. V, Nazarenko, S., Schiraldi, D., Hiltner, A., and Baer, E., Oxygen Barrier Properties of Crystallized and Talc-Filled Poly(ethylene terejiithalate), J. Polym. Sci. Part B Polymer Physics 37, 847 (1999). 

H.G.B. Premlal, H. Ismail, and A.A. Baharin, Comparison of the mechanical properties of rice husk powder filled polypropylene composites with talc filled polypropylene composites. Polym. Test. 21(7), 833-839, (2002). 

Table 12.5 Typical properties for talc-filled homopolymer and copolymer PP [5, 18].

The source of the talc ore also appears to lie important in applications where resistance to ultraviolet (UV) light is required. As shown in Figs. 8.22 and 8.23, the Cimpact 710 retains more of its stiffness than a Montana-based product after 2000 hours of UV exposure in a QUV unit. The tensile property reductions (Fig. 8.22) are about the same for both talc-filled products, which are better than the neat resin. 

A comparison of the properties of surface-treated phlogopite mica with talc, calcium carbonate, glass, and the unfilled resin is given in a technical bulletin produced by Marietta Resources International, Ltd. (10). Table 14.7 shows that 40 wt% mica-filled polypropylene (Profax 6523) had a higher flexural modulus than 30 wt% glass fiber-filled polypropylene (1.04 X 10 psi versus 0.93 X 10 psi). The compound filled with 40 wt% surface-modified mica also had higher Izod impact than the 40 wt% talc-filled compound (0.65 versus 0.45 ft-lb/in). 

The apparatus for the measurement of this property is described in DIN 53464 [7]. Bertacchi and co-workers [8] have reported computer-simulated mould shrinkage studies on talc-filled PP, glass-reinforced PA and a PC/acrylonitrile-butadiene-styrene (ABS) blend. 

Apparatus for the measurement of this property according to DIN 53464 [56] are available from ATS FAAR (Table 2.6). Beracchi and coworkers [60] reported on computer-simulatedmoldshrinkage studies on talc-filled polypropylene, glass-reinforced polyamide, and polycarbonate/acrylonitrile-butadiene-styrene blends. 

Yua Sheng et al. [153] and Leong et al. [155] measured the tensile, flexural, and impact properties of ultra-fine-talc-filled polypropylene composites. Experimental results indicated that the addition of talc inflnenced the crystallization, morphology, and mechanical properties of talc-polypropylene composites. When the talc content was increased from 0% to 25%, the crystallinity of the polypropylene phase reached a maximnm at 15% talc and the tensile and flexural strengths of talc-polypropylene composites also attained a maximum, while the impact strength declined to its lowest level. Scanning electron microscopy photographs of impact... 

Saq an et al. [106] determined the physical properties of a talc-filled polypropylene composite. Measurements included volume resistivity, electrical conductivity, and volume resistivity. The effect of talc content and temperature on the thermal, elastic, and electrical properties of the polymer was studied. 

Seldon [10] measured the weld line strength and impact, and flexural and tensile properties of injection-molded specimens of glass fiber-reinforced polyamide 6 and talc-filled polypropylene (PP). Further information was obtained by examination of fracture surfaces by scanning electron microscopy. 

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