Calcium carbonate filled polystyrene

Figure 2.5 Shear viscosity of uncoated and stearate-coated calcium carbonate-filled polystyrene melt versus shear rate. (Reproduced with permission from Ref [10], Chapters.)...

Figure 7.7 shows the effect of surface treatment on 30% calcium carbonate filled polystyrene [27]. It can be seen that the data are presented in both forms of representations. Nj vs. j (Figure 7.7(a)) and Ni vs. Ti2 (Figure 7.7(b)). In Figure 7.7(a), it appears that surface treatment reduces elasticity to a level even below that of the pure poljmaer. However, conclusions drawn from this type of representation... 

Figure 7.7(a) Variation of primary normal stress difference with shear rate for calcium carbonate filled polystyrene containing 30% untreated and treated filler. (Reprinted from Ref. 27 with kind permission from Society of Plastics Engineers Inc.. 

Figure 9.11 shows the effect of surface treatment on extensional viscosity for 30% calcium carbonate filled polystyrene [27]. The data are presented in two forms, namely steady state extensional viscosity vs. extensional rate in Figure 9.11(a) and steady state extensional viscosity vs. tensile stress in Figure 9.11(b). Irrespective of the type of data representation, it is seen that surface treated calcium carbonate reduces the level of extensional viscosity and brings it closer to that of the unfilled polymer. The yield stress value is reduced considerably though the values of the ratio of yield stress in extension to that of shear is still maintained nearer to the von Mises value of 1.73 as can be seen from Table 9.1. Surface treatment tends to modify the forces of particle-particle interaction and hence show reduced yield stress values due to lowering of the interaction forces [2,27]. 

From about 1980, there have been extensive investigations of the shear viscosity of rubber-carbon black compounds and related filled polymer melts. Yield values in polystyrene-carbon black compounds in shear flow were found by Lobe and vhiite [L15] in 1979 and by Tanaka and White [Tl] in 1980 for polystyrene with calcium carbonate and titanium dioxide as well as carbon black. From 1982, White and coworkers found yield values in compounds containing butadiene-styrene copolymer [Ml, M37, S12, S18, T7, W29], polyiso-prene [M33, M37, S12, S18], polychloroprene [S18], and ethylene-propylene terpolymer [OlO, S18]. Typical shear viscosity-shear stress data for rubber-carbon black compounds are shown in Figs. 5(a) and (b). White et al. [S12, S18, W28] fit these data with both Eq. (56) and die expression... 

Figure 13.7 A series of filled polystyrenes, illustrating the increases in glassy shear modulus, and apparent or slight increases in the glass transition temperature. Material , control v, 20% mica A, 40% mica o, 20% calcium carbonate 40% asbestos o, 60% mica >, 20% asbestos , 60% asbestos.

---