Copolymer master rheogram

Tlie liquid-crystalline hydroxy benzoic acid/poly(ethylene terephthalate) (HBA/PET) copolymer master rheogram given in Fig. 4.37, however, is not amenable to a curve fit by any of the models discussed above. The reason is because the shape of the unified curve for this liquid-crystalline copolymer is radically different from those obtained for other thermoplastics. There are two shear-thinning regions separated by a short plateau as can be seen in Fig. 4.37. A new equation of the following form is thus suggested [12] ... 

Table B2 Details of Data Used for Master Rheograms of Copolymers In Figs. 430-436 ...

The fourth chapter begins with the origin and definition of MFI. It then develops the fundamentals of the unification technique based on a strong theoretical rationale. A demonstration of the use of this technique is followed by ample master rheograms of shear viscosity for a long list of common homopolymers, copolymers, blends, PVC formulations, and filled and recycled polymers. 

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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