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Determination of polybutylene terephthalate polycondensation equilibrium constant using a batch reactor
Author(s) -
Darda Pranay Jairam,
Hogendoorn Kees,
Molenkamp Tjaart,
Versteeg Geert
Publication year - 2004
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200450222
Subject(s) - condensation polymer , polybutylene terephthalate , equilibrium constant , polymerization , materials science , polymer chemistry , degree of polymerization , thermodynamics , chemistry , polyester , polymer , composite material , physics
Abstract The PBT polycondensation equilibrium constant at 255°C was determined using a batch reactor. Starting from a Polybutylene terephthalate (PBT) prepolymer having a degree of polymerisation of 12.7, equilibrium experiments were performed in the range of 1 to 50 mbar. The equilibrium degree of polymerisation ( i ) was determined indirectly using dilute solution viscometry of a solution of 1 weight % PBT in m ‐ cresol. The degree of polymerisation of PBT obtained at equilibrium in the range of 1 to 50 mbar at 255°C as a function of the BDO partial pressure (mbar) could be expressed by: i = 111.47 − 86.18 exp (−1.14 $P^{-1.44}_{bdo}$ bdo −1.44 ). The equilibrium solubility of 1,4 butanediol (BDO) in the PBT melt was derived form the BDO partial pressure using the Flory ‐ Huggins theory. The PBT polycondensation reaction equilibrium constant was related to the degree of polymerisation by the equation: $K_e = {0.187 \over 1 -19243 e^{-0.3932}} $ in the range i = 26 − 100. The PBT polycondensation equilibrium constant at high degrees of polymerisation is in line with literature data and thermodynamics.