Kinetic analysis of the melt acidolytic (Co) polycondensation of fully aromatic polyesters

Abstract

Experiments to determine the initial reaction rate constants of acidolytic (co)polycondensations of fully aromatic polyesters were conducted in the melt. The initial reaction rate was determined by constant monitoring of the evolution of acetic acid. Both homo‐polycondensation of p‐acetoxybenzoic acid (pAcBA) and copolycondensation of 2 parts pAcBA, 1 part p,p'‐bisacetoxybiphenyl (BAcBP), and 1 part terephthalic acid (TPA) were studied in a batch reactor under nonisothermal conditions. Next to this, the effect of the presence of the catalyst N‐methylimidazole (NMI) on the (co)polycondensations was checked. From the series of experiments it was concluded that the reactivities of acetoxy groups of pAcBA and BAcBP were equal. Furthermore, it was found that the catalyst NMI showed an accelerating effect in the homo‐ and copolycondensations, thereby acting as a “conventional catalyst.” The postulated reaction mechanism for the (co)polycondensations is in accordance with the reaction mechanism for acidolysis of esters by carboxylic acids as suggested by Loncrini. The reactivity of TPA could not be determined by the method used because of the poor solubility of TPA in the reaction mixture. © 1992 John Wiley & Sons, Inc.

Synthesis of liquid crystalline polymers from polyethylene terephthalate and 4‐acetoxybenzoic acid: A kinetic study

“…Generally, the increase in reaction Figure 9 Third order model application to the uncatalyzed polymerization of PET50/OB50. temperature is associated with an increase in the values of k. This is in agreement with the findings of Vulic and Schulpen, 34 Mathew et al 35 and Williams et al. 3 However, this is not observed for the uncatalyzed polymerization of PET70/OB30.…”

Polyesters

“…286 The reaction of terephthalic acid with aromatic diacetates without added catalyst has been examined assuming first order in each reactant. 287 The kinetics is rather complex since reaction takes place in a multiphase system, terephthalic acid being insoluble in reaction medium.…”

Fabrication and Thermal Characteristics of Liquid Crystalline Copolyester/OMMT Nanocomposite Films

“…The copolyester was synthesized using a conventional acidolysis method described in other literature. [15][16][17][18] In order to make solvent cast LCC/OMMT nanocomposite films, initially the copolyester was dissolved in p-chlorophenol as a solvent at 120 • C at less than 10% by weight. The Cloisite 20A, OMMT powder supplied by Southern Clay Products (USA), was a fine powder with an average particle diameter of 75 µm in dry state, with a cationic exchange capacity of 0.95 meq/g.…”