Talc Filled PP

Control of the average particle size, the particle size distribution, the purity and the aspect ratio of the filler is necessary to achieve consistent product quality in talc filled PP. In some grades of talc filled PP, water absorption may be an important factor. This will affect the surface appearance of the moulded product and the adhesion of the resin to the filler. 

The main applications for talc filled PP grades are in car heater casing, motor housing, dryer drums, textile bobbins, industrial and agriculture plant components. Talc filled PP sheet is used as an alternative to carton board. 

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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. 

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. 

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.]...

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. 

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]. 

Talc-filled PP LICA 12 Increase in PP MWD Increased dispersion, decreased melt viscosity Increased impact strength, reduced Tg [29]... 

Noble Polymers supplies a 6% nanoclay-PP composite for the structural seat back of the Honda Accura TL 2004 car. It replaces a 30% glass PP compound in the seat back. Noble Polymers is also targeting the replacement of 20% glass fibre reinforced PP in office furniture parts. Southern Clay Products supplies Cloisite nanocomposite external parts to General Motors for its Impala vehicle, in competition with talc-filled PP. 

Selden and co-workers [59] measured weld line tensile strength of injection moulded glass fibre reinforced PA 6 and talc filled PP. Fracture surfaces were also examined using SEM. 

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. 

Electrical conductivity measurements have been reported on a wide range of polymers including carbon nanofibre reinforced HOPE [52], carbon black filled LDPE-ethylene methyl acrylate composites [28], carbon black filled HDPE [53], carbon black reinforced PP [27], talc filled PP [54], copper particle modified epoxy resins [55], epoxy and epoxy-haematite nanorod composites [56], polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) blends [57], polyacrylonitrile based carbon fibre/PC composites [58], PC/MnCli composite films [59], titanocene polyester derivatives of terephthalic acid [60], lithium trifluoromethane sulfonamide doped PS-block-polyethylene oxide (PEO) copolymers [61], boron containing PVA derived ceramic organic semiconductors [62], sodium lanthanum tetrafluoride complexed with PEO [63], PC, acrylonitrile butadiene [64], blends of polyethylene dioxythiophene/ polystyrene sulfonate, PVC and PEO [65], EVA copolymer/carbon fibre conductive composites [66], carbon nanofibre modified thermotropic liquid crystalline polymers [67], PPY [68], PPY/PP/montmorillonite composites [69], carbon fibre reinforced PDMS-PPY composites [29], PANI [70], epoxy resin/PANI dodecylbenzene sulfonic acid blends [71], PANI/PA 6,6 composites [72], carbon fibre EVA composites [66], HDPE carbon fibre nanocomposites [52] and PPS [73]. 

A cross-section of an injection-molded PP shows a clear skin-core structure imder a polarizing microscope. Figure 1 shows the crystal orientation states of the skin and core layers [6]. In the skin layer, the c-axis-oriented and a -axis-oriented crystals are present. Their b-axis distribution is almost uniform around the MD. In the core layer, the c- and a -axes weakly orient in the MD and the b-axes uniformly distribute about it. Injection molding of talc filled PP shows a peculiar crystal orientation the plate planes of talc particles orient parallel to the molding siuTace and the b-axes of PP crystals orient in the thickness direction [7],... 

Morawetz H (1995) Polymers the origins and growth of a science. Dover Publications, New York Mueller CD, Nazarenko S, Ebeling T, Schuman TL, Hiltner A, Baer E (1997) Novel structures by microlayer coextrusion - Talc filled PP, PC/SAN and HDPE/LLDPE. Polymer Eng. Sci 37 355-362. DOI 10.1002/pen. 11678... 

Gibert et al. [303] have reported a study of talc filled PP/PE copolymers flame retarded with Mg(OH)2 or brominated trimethylphenylindane/ Sb203 (and in combination), using TG-DTA on-line coupled with FTIR. A good correlation was found between the maxima of Gram-Schmidt curves and DTG, and between DTA/TG-FTIR conclusions and Are resistance tests. The DTA/TG-FTIR coupling also showed the limitation of use of Mg(OH)2 as a flame retardant. 

Density separation is complicated in many cases because the density ranges of two given plastics may cross. Separation is further complicated by the incorporation of fillers, air (in foams), adhesives or other additives in some plastics as they can substantially change the density. For example, 15% talc filled PP has a density similar to that of ABS (1.02-1.20 g cm ) and may be used in similar applications resulting in a difficult mixture to separate [76]. An alternative to simple density separation would be required in such a case. 

Fan shrouds, radiator parts, air flow meter o HVAC components in Talc-filled PP... 

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