Swollen-state polymerization of poly(ethylene terephthalate): kinetic analysis of reaction rate and polymerization conditions

Rheological study of the reaction kinetics in a poly(ethylene terephthalate) melt

“…In our opinion, the most reliable results for comparison are published by Tomita [18] and by Tate and Ishimaru [30], as in both papers nitrogen atmosphere was used and the same assumptions about the chemical reactions were made. Tomita investigated the polymerization process of bis(2-hydroxyethyl) terephthalate in a glass vessel [18] and Tate and Ishimaru the production of ultra-high molecular weight PET by swollen state polymerization [30]. The comparison of our results with these studies is shown in Table 2.…”

Reaction rate enhancement during swollen-state polymerization of poly(ethylene terephthalate)

“…If the extent of 30ЊC in a mixture of phenol and 1,1,2,2-tetrachloswelling changes during the reaction, then the roethane (60 : 40, v/v). The number-average mocondensate diffusivities and reaction rate conlecular weight M V n Å 192 n V is determined using stants keep changing, making the determination the following equation 4 : of the kinetics difficult. Further, the concentration of the reactants will also be continuously affected IV Å 7.5 1 10 04 (M U n ) 0.68 (16) by continuous change in swelling.…”

Broadening of molecular-weight distribution in solid-state polymerization resulting from condensate diffusion

“…In addition, raising the temperature may be counterproductive if K decreases or k f increases more rapidly than D. A more elegant method of raising the condensate diffusivity is to introduce a plasticizing agent, which will effectively increase the free volume of the polymer and consequently enhance molecular mobility and increase the diffusion coefficient. 6,13,16,17 Of particular interest are nontoxic penetrants such as supercritical carbon dioxide, which plasticize the polymer without contaminating it or generating difficult-to-recycle waste streams. 5,6 Figure 6(a,b) shows the effect of particle size on average molecular weight and polydispersity for a phenol diffusion coefficient of 10 Ϫ7 cm 2 /s.…”

“…7 Recently, several research groups 8 -10 have developed kinetic models for the solid-state polymerization of PET and have investigated the effects of condensate (ethylene glycol) diffusion on the molecular-weight evolution. Other aspects of the SSP of PET have also been examined, such as the effect of particle size, 9,[11][12][13][14] the type of purge gas, 15 the flow rate of purge gas, [12][13][14] and the use of plasticizers to increase the rate of polycondensation. 6,13,16,17 Models for the SSP of nylon-6 3 and nylon-6,6 10 have also been developed.…”

“…19 The existence of a molecular-weight gradient has been demonstrated in previous theoretical 8 and experimental 20 studies. However, the studies that have examined molecular-weight distribution in solidstate polymerization 13,21 have given only casual attention to the polydispersity values exceeding the theoretical limit.…”