Talc filled

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. 

Unfilled talc-filled coupled glass- Chip- Alumi- Mild... 

The extraction time has been observed to vary linearly with polymer density and decreases with smaller particle size [78,79]. The extraction time varies considerably for different solvents and additives. Small particle sizes are often essential to complete the extraction in reasonable times, and the solvents must be carefully selected to swell the polymer to dissolve the additives quantitatively. By powdering PP to 50 mesh size, 98 % extraction of BHT can be achieved by shaking at room temperature for 30 min with carbon disulfide. With isooctane the same recovery requires 125 min Santonox is extractable quantitatively with iso-octane only after 2000mm. The choice of solvent significantly influences the duration of the extraction. For example talc filled PP can be extracted in 72 h with chloroform, but needs only 24 h with THF [80]. pH plays a role in extracting weakly acidic and basic organic solutes, but is rarely addressed explicitly as a parameter. 

Talc-filled reinforced polypropylene films and foils are beginning to replace PVC for corrugated board, labels. .. 

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 ... 

For example, the scratch resistance of talc-filled TPOs modified with 2-3% silicone from masterbatches is significantly improved and visible whitening is suppressed under conditions that damage the same TPO without silicone. Paintability must be verified but a low silicone level (2.5% for example) does not affect paintability, and weathering resistance increases showing less change in aspect than the control without silicone. 

For a given grade of 20% talc-filled polypropylene, Figure 4.13 displays two examples of SN or Wohler s curves concerning flexural tests ... 

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. 

Figure 7 shows the effect of filler particle shape on the viscosity of filled polypropylene melts, containing glass beads and talc particles, of similar density, loading and particle size distribution. The greater viscosity of the talc-filled composition was attributed to increased contact and surface interaction between these irregularly shaped particles. 

In more recent work, talc-filled polystyrene compounds, with various filler volume fractions, have been processed by compression moulding and through a variety of slit, capillary, rectangular and annular dies [37]. Particle orientation has been characterised using wide angle X-ray diffraction, then expressed in the form of pole figures, and by scanning electron microscopy. It was concluded that... 

Shear yield behaviour of polymer melts containing plate-like filler particles is also prevalent and is clearly shown in Fig. 8 for talc-filled polystyrene. In this system an estimate was made of shear yield values, which were found to increase with increasing particle loading and decreasing particle size. These results are compared with reported yield values for other particulate-filled polymers in Table 2. It is evident that shear yield values also depend on the particle type and thermoplastic matrix used. 

Gay is used as a filler in compounding paper and rubber. Talc, a naturally occurring fibrouslike hydrated magnesium silicate, is used to improve the thermal resistance of polypropylene (PP). Since talc-filled PP is much more resistant to heat than unfilled PP, it is used in automotive accessories subject to high temperatures. Over 40 million tons of talc are used annually as a filler. 

Mclnemey LF, Kao N, Bhattacharya SN (2003) Melt strength and extensibility of talc-filled polypropylene. Polym Eng Sd 43 1821-1829... 

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. ... 

Figure 8.10. Effect of phosphate concentration on the tensile yield stress of talc filled polypropylene. [Adapted, by permission, from Liu Z, Gilbert M, J. Appl. Polym. Sci., 59, No.7, 1996, 1087-98.]...

Figure 8.48. Crack length vs. number of cycles for talc filled PC/ABS blend. [Adapted, by pennission, from Seibel S R, Moet A, Bank D H, Sehanobish K, Antec 95. Volume III. Conference proceedings, Boston, Ma, 7th-llth May 1995, 3966-70.]...

Talc filled thermoplastic materials were studied in rheometers of different geometries (elongational, capillary, parallel plate). Geometry of the testing method and the flow paths had an important influence on the orientation of talc particles. In addition to flow decrease, an increased concentration of filler had a pronounced effect on both flow and orientation. The cross-sectional distribution of particles de-... 

Figure 9.19. Complex viscosity of talc filled PP vs. frequency. [Data from Chang Ho Suh, White J L, J. Non-Newtonian Fluid Mechanics, 62, Nos.2/3, 1996, 175-206.]...

Major results. Figure 8.40 shows that the void density or whitening of talc filled polypropylene (relative to average scattering and scattering difference) increases... 

Figure 14.19. Crystallization temperature of talc filled PP vs. UV exposure time. [Adapted, by permission, from Rabello M S, White J R, Polym. Composites, 17. No.5,1996, 691-704.]...

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. 

Polypropylene—talc filled (1-1.5). Better thermoforming, but WVP only slightly better than PVC. Chalk filled PP is also available. 

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