Thermal degradation of poly(2,2′,-propane-bis-4-phenyl carbonate) or bisphenol A polycarbonate (PC) alone and in presence of metal oxide as additives have been discussed. Thermal degradation of PC in presence of metal oxide additives may be surface induced catalytic thermo-oxidative degradation. Some metal oxides retard thermo-oxidative degradation of PC.
Authors:H. Polli, L. Pontes, M. Souza, V. Fernandes Jr, and A. Araujo
The degradation kinetics
of polycarbonate with flame retardant additive was investigated by means of
thermogravimetric analysis. The samples were heated from 30 to 900C in
nitrogen atmosphere, with three different heating rates: 5, 10 and 20C
min–1. The Vyazovkin model-free kinetics
method was applied to calculate the activation energy (Ea)
of the degradation process as a function of conversion and temperature. The
results indicated that the polycarbonate without flame retardant additive
starts to loose mass slightly over 380C and the polycarbonate with flame
retardant additive, slightly over 390C (with heating rate of 5C
min–1). The activation energy for flame retardant
polycarbonate and normal polycarbonate were 190 and 165 kJ mol–1,
Bisphenol-A polycarbonate (BAPC) was crystallised by exposure to acetone vapours for a period of 9 h; it developed a 20% crystallinity
according to WAXS measurements. The samples of semi-crystalline BAPC were then submitted to a series of thermal treatments
including annealing, self-nucleation and subsequent isothermal crystallizations. The results showed that the polymer possesses
a remarkable crystalline memory and a much faster recrystallization and reorganization capacity (lamellar thickening) than
its very low thermal crystallization rate. This peculiar crystallization behaviour probably stems from its rigid backbone
Summary Volume and enthalpy relaxation in polycarbonate subjected to double temperature jumps in the Tg region has been analysed. It concerns both initial Tdown-jump from equilibrium above Tg to consolidation temperature below Tg and fina1 Tup-jump to relaxation temperature, also below Tg. The measured H and V data after Tup-jump were compared with respect to aging time calculating (dH/dV) ratio denoted as aging bulk modulus, Ka. According this new methodology H and V relaxation response after Tup-jump demonstrates differences in relaxation responses.
Thermal decomposition of polyurethane, epoxy, poly(diallyl phthalate), polycarbonate, and poly(phenylene sulfide) was examined
using a combination of thermal and chemical analysis techniques. Thermal gravimetric analysis with simultaneous analysis of
evolved gases by Fourier transform infrared spectroscopy, differential scanning calorimetry, and gas chromatography coupled
with Fourier transform infrared spectroscopy were used to obtain rate data, determine enthalpy changes, and identify decomposition
products. Examination of the evolved decomposition products indicated a common set of chain scission mechanisms involving
the aromatic moieties in each of the polymer materials studied.
Authors:Arunkumar Lagashetty, H. Vijayanand, S. Basavaraja, Mahesh Bedre, and A. Venkataraman
in a non-conducting polymer matrix [ 14 ]. Looking into the wide application of these, in this study, we have prepared polycarbonate nanocomposite films by dispersing CuO and γ-Fe 2 O 3 material in the polycarbonate matrix through solvent casting
Authors:Bhupendra Singh Rathore, Mulayam Singh Gaur, and Kripa Shanker Singh
Polycarbonate (PC) pellets were supplied by Redox (India) and Silicon dioxide (SiO 2 ) nanoparticles of size 5 nm were supplied by Sigma-Aldrich have been used in this study. The pristine and nanocomposites samples in form of film were prepared by solution
Authors:Y. Kobayashi, K. Hirata, Y. Ujihira, and K. Itoh
Diffusion coefficients of positronium (Ps) in polycarbonate (PC) have been determined at temperatures between 20 and 300 K by means of positron lifetime spectroscopy. 2,2-dinitrobiphenyl (DNB) was added to the polymer as a Ps quencher and the diffusion coefficients were determined from measured Ps quenching rate constants, assuming that the reaction between Ps and DNB is completely diffusion-controlled.