MFI Correlations in Polymer Product Fabrication

Nakajima [19] has shown how die swell could be predicted through knowledge of the MFI. The salient features of his approach are as follows. He used a material function, namely, the time constant X defined as 

The values of Ai, q, Bi, and r were determined from the time constant versus shear rate curves [19]. 

Using Eqs. (9.17)-(9.22), the die swell could be calculated for a given sample of known MFI. The values of die swell thus calculated for over 100 observed 

Romanini et al. [23] also studied the dependence of the swelling ratio (after annealing of PE samples) to the MFI (taken under identical conditions of load and temperature) with changes in the molecular weight as shown in Fig. 9.20. The numbers in Fig. 9.20 corresponds to the sample numbers given in Table 9.3, which outlines the main chemicophysical characteristics of the polymers used samples 1-5 were obtained in a tubular reactor under specific reaction conditions, whereas samples 6-14 were produced in an autoclave divided 

The above equation suggested by Guillet et al. [22] was later corrected by Combs et al. [24], as a mistake was noted in the conversion of the units used in the equation. The actual data reported by Guillet et al. [22] were correct, but the equation was different by a factor 41.62 or (2.54). The correct equation, therefore, relating MS and MFI is as follows  

For convenience, in order to eliminate the proportionality factor, Eq. (9.19) was written as 

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