Rheological and calorimetric properties of recycled bisphenol A poly(carbonate)

摘要

Mechanical recycling of engineering polycarbonate wastes provides an interesting way to decrease the impact on environment, if the degradation due to successive processing is properly characterized. We analyzed polycarbonate (PC) degradation generated by eight successive recycling, using rheological, calorimetric and colorimetric tools at each step. From the first to the fifth recycling, an increase of storage modulus E′ (at T = 30℃ and f= 1 Hz) in both bending and tension mode is observed, together with a decrease of the Newtonian limit viscosity η_0 (at T=240℃ and γ = 0.1 s~(-1)). Moreover, a decrease of T_g of about 3.5℃ and of ΔC_p at T_g is noticed from the first to the eighth recycling. Accelerated aging under UV irradiation shows a more rapid coloration of recycled PC. All these results evidence a decrease of molar mass resulting from thermomecanical stress encountered by the PC during recycling. This modification of polycarbonate properties, which remaining good, must be taken into account to adjust the processing conditions and determine the possible applications.