Non-isothermal degradation kinetics of poly (2,2′-dihydroxybiphenyl)

Abstract

Catalytic oxidative polymerization of 2,2′-dihydroxybiphenyl (DHBP) was performed by using Schiff base polymer-Cu (II) complex and hydrogen peroxide as catalyst and oxidant, respectively. According to size exclusion chromatography (SEC) analysis, the number-average molecular weight (Mn), weight-average molecular weight (Mw) and polydispersity index (PDI) values of poly (2,2′-dihydroxybiphenyl) (PDHBP) were found to be 37,500, 90,000 g mol−1 and 2.4, respectively. The thermal degradation kinetics was investigated by thermogravimetric analysis in dynamic nitrogen atmosphere at four different heating rates: 5, 10, 15 and 20 °C min−1. The derivative thermogravimetry curves of PDHBP showed that its thermal degradation process had one weight-loss step. The apparent activation energies of thermal decomposition for PDHBP as determined by Tang, Flynn–Wall–Ozawa (FWO), Kissenger–Akahira–Sunose (KAS), Coats–Redfern (CR) and Invariant kinetic parameter (IKP) methods were 109.1, 109.0, 110.0, 108.4 and 109.8 kJ mol−1, respectively. The mechanism function and pre-exponential factor were determined by master plots and Criado–Malek–Ortega method. The most likely decomposition process was a Dn Deceleration type in terms of the CR, master plots and Criado–Malek–Ortega results.