Master rheogram for

The master rheogram for HDPE is shown in Fig. 4.12. The data used in this curve involve three sources [30,31,46] and includes 146 data points. The viscosity versus shear rate curves were available for a shear-rate range from 0.01 to 1000/s and at eight different temperatures from 170 C to 220°C (Ihble B1 of Appendix B). 

Figure 4.13 shows a plot of X MFI versus y/MFI, which is the master rheogram for UHMWPE that is grade and temperature invariant. 

The master rheogram for aorylic is shown in Fig. 4.18. Atotal of 105 data points covming a shear-rate range from 1 to 10,000/s have been used [56]. The bulk of the data has been taken from Westover [35] and conqilemented by 12 data... 

The master rheogram for poly(ethylene terephthalate) (PEI) is shown in Fig. 4.21. cept for 4 data points taken from a research paper by Wu [61], the 169 data points were obtained from a single source, namely, the manufacturer [62]. All types of grades of PET (i.e., fiber, molding, tire cord, bottle) have been unified on the master rheogram [56]. in the case of nylon, the Newtonian plateau is very distinct and covers a wide range of shear rate. The deviation from the Newtonian behavior is also not too pronounced even at considerably higher shear rates. 

The master rheogram for SAN is shown in Fig. 4.30. A total of 80 data points have been used [30], covering a limited shear-rate range from 20 to 600/s (Table B2 of Appendix B). The viscosity versus shear rate data was made available from the manufacturer [51]. This data was for two different grades of SAN (lyrll 860B and lyril 867B) at four different temperatures (200 C, 215 C, 230"C, and 250 C). 

The master rheogram for SBS is given in Fig. 4.31. This unified curve has been produced [77] using limited data from a single source [39]. The 27 data points included have been taken from viscosity versus shear rate curve spanning 6 temperatures between 110°C and 210 C and covering a shear-rate range from 0.1 to 1000/s (Table B2 of Appendix B). 

The master rheogram for ABS shown in Fig. 432 was formed [77] by using viscosity versus shear rate data from two research p rs [78,79], In one case [78], the available data were for one grade of ABS, namely, Kralastic MH at three different temperatures of 180°C, 200 C, and 220°C. In the other case [79], at a single temperature of 210°C, viscosity versus shear rate data for two... 

The viscosity versus shear rate data for VCVA was obtained from a book [35] and a research paper [80]. The data were for a limited shear rate fiom 0.1 to 600/s and covered a limited temperature range from 140°C to 180°C (Bible B2 of Appendix B). Nevertheless, this coverage was within the useful and relevant range for this polymer. A total of 32 data points were used [77] for unifying the curve to form the master rheogram for VCVA shown in Fig. 4.33. 

The master rheogram for ethylene-vinyl acetate (EVA) is shown in Fig. 4.34. This unified curve was obtained [77] from limited data on just one grade of EVA, namely, ALAIHON EA A 3185. The viscosity versus shear rate data were available [40,41] at seven temperatures between 60°C and 125°C, covering a shear-rate range from 0.01 to 500/s (Table B2 of ipendix B). 

The viscosity versus shear rate data for polyester elastomer (Hytrel) were obtained from its technical brochure on rheology and handling suf lied by the manufacturer [81] (Table B2 of Appendix B). The data covered a shear-rate range of 10-3000/s for five different grades of Hytrel. For three of the grades, the data temperature was 220 C, whereas for the other two grades, they were 180 C and 240 C, respectively. A total of 20 data points were used [77] in the unification process to obtain the master rheogram for polyester elastomer (Hytrel) shown in Fig. 4.35. 

The master rheogram for olefinic-type thermoplastic elastomer (TPE) obtained by the unification [77] of viscosity versus shear rate data from two sources [82,83] is shown in Fig. 4.36. The data covers a number of different grades of TPE over a range of shear rate from 1 to 1000/s but is limited to the two temperatures of 20S C and 230°C. A total of 44 data points have been used in the unification process (Table B2 of Appendix B). 

The master rheogram for PS/POM blend shown in Fig. 4.41 is based on limited data [87] taken from a single source [91] at a fixed temperature of 210°C. A total of 20 data points were taken from the viscosity data that spanned a shear-rate range from 20 to 400/s for 3 compositions (0.9/0.1, 0.5/0.S, 0.2/0.8) of PS/ POM, in addition to the pure components (Table B3 of Appendix B). 

The master rheograms for filled polymers have been given by Shenoy et al. [95] on a limited number of systems. These are for filled systems of LDPE, HOPE, PP, PS, Nyltm, PET, and PC using date from Refs. 33,44,59-61,65, %-102. The various filled polymer systems analyzed by them are summarized in Table BS of pendix B. 

It was found [95] that the master rheograms for each of filled systems was no different from that for the unfilled systems over a broad range of shear rates. Only in the very low-shear-rate region, the master curve is not unique due to the yield stress behavior, which is known to occur for filled systems as can be seen from one typical curve shown in Fig. 4.44. This aspect was depicted [95] only for HDPE, where a clear fork was shown to exist in the low-shear-rate region. Although in other curves the forks were not shown [95], it does not imply their nonexistence. In fact, if sufficient data in the low-shear region on filled systems was available, then the fork would be present in all the curves. However, the matter of prime importance is that the master curve in the... 

The chapters that need comments are those from Chapter 4 onward. For example, in Chapter 4, a different type of unification approach is described and used for obtaining master rheograms for a number of polymers which include... 

In the case of extensional viscosity, unified curves have been presented for a limited number of cases and the data used for coalescence are also-limited. Because of the difficulties in measurement of extensional viscosity, the reliability of the data is often questionable. Because the original data cannot be as trustworthy as in the case of shear viscosity or complex viscoaty data, the master curves of extensional data should be looked at in the same light. In the case dt shear viscosify, the master rheograms for the filled polymers have been shown to be the same as those for the unfilled system. is, of course, true in the medium to high shear-rate region. In the low-shear-rate region, however, the effects of yield stress would dominate and the uniqueness of the curve will be... 

Chapter 4 gives master rheograms for a long list of polymers but, by no means, includes all known thermc lastics. It is, therefore, beneficial to establish the master rheograms for the thermoplastics not considered in the book along with any new polymers, time and again, when they get developed in the future. 

The flow parameter that is readily accessible to most processors is the melt flow index (MFI). The MFI is either specified by the thermoplastics raw material supplier or can be easily measured using a relatively ine nsive apparatus. It is a single-point viscosity measurement at a relatively low shear rate and temperature. Earlier, it was often said that MFI gives a dot when actually what is needed is a plot for the polymer processors. However, this is not true now because of a unique approach developed for estimating the rheogram merely from the knowledge of the MFI. This approach is discussed in detail in this chapter, and unified master rheograms for most polymers are presented. 

The master rheogram for PP shown in Fig. 4.15 involves data from three sources [30,33,50] and includes 180 data points (Table B1 of Appendix B). Similar to the case of LDPE, one set of data was generated on the Weissenberg Rheogoniometer and Instron Capillary Rheometer using three different grades of PP, each at three different temperatures. These data were complemented by viscosity versus shear data obtained on different grades of PP from two different manufacturers. One set was obtained courtesy of J.P. Whelan, Amoco Chemical Cor-... 

Viscosity versus shear rate data from two books [35,59] and two research papers [34,60] were used to form [56] the master rheogram for nylon (PA) shown in Fig. 4.20. A total of 78 data points covering a shear-rate range from 1 to 10,0(X)/s... 

Viscosity versus shear rate curves for two different compositions of a hydroxy benzoic acid/poly(ethylene terephthalate) copolymer (HBA/PET) at various temperatures were used [84] in the formation of the master rheogram for the liquid-crystalline polymer shown in Fig. 4.37. The data for 80 mole% of HBA at six different temperatures ranging from 275°C to 330 C were taken from Ref. 42. In order to eliminate operator and interlaboratory errors, the data on the same composition at one representative temperature of 275°C was also used from another source [85]. The other composition of HBA/PET chosen was 60 mole% and again from two different sources [42,86]. From one source [42], the viscosity data for 60 mole% of HBA at three different temperatures between 210°C and 300 C was used, where as from the other [86], three different temperatures between 260°C and 285 C was used. A total of 51 data points covering a shear-rate range from 2 to 8000/s have been included (Table B3 of Appendix B) in the unification process to form the master rheogram in Fig. 4.37. 

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