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Continuous production of polyester‐poly(ethylene terephthalate) resins in melt‐phase and solid‐state reactors
Author(s) -
Chen ChiChin
Publication year - 2017
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.24445
Subject(s) - materials science , pellets , condensation polymer , polyester , diffusion , chemical engineering , fluidized bed , catalysis , reaction rate , polymer chemistry , composite material , organic chemistry , polymer , thermodynamics , chemistry , physics , engineering
A simple reaction model has applied net polycondensation rates to predict the steady‐state performance of three distinct continuous processes for manufacturing polyester‐PET resins. A net melt‐phase polycondensation rate was described by the simple second‐order kinetics. A net solid‐state polycondensation rate was assumed to follow the modified second‐order kinetics with respect to active end group concentration. A moving‐packed bed requires a longer residence time to deal with the diffusion‐limited SSP of standard pellets or challenging pastilles. The calculations and data showed low IV pastilles to have much slower diffusion‐controlled SSP rates than medium IV pellets. The tanks‐in‐series model demonstrated a narrow RTD in a gas fluidization bed with five mixing stages. Higher reaction temperatures may significantly increase the low diffusion resistance SSP rates of smaller beads or micro‐pellets in a gas‐fluidized reactor. The reaction‐controlled SSP of micro‐beads becomes apparent at 230°C. The high IV melt resins may challenge the slow reaction rates of Ti or Al‐catalyzed SSP resins. The efficacy of catalyst promoters on Ti activity enhancement may depend upon various ligands in Ti glycolate, Ti citrate, or titanic acid. The thermo‐oxidative stability of Ti or Al‐catalyzed resins may decrease at higher hot air drying temperatures (188°C or above). POLYM. ENG. SCI., 57:505–519, 2017. © 2016 Society of Plastics Engineers