Study On Aging And Degradation Of Poly(Propylene Carbonate)/layered Silicate Nanocomposites

Poly(propylene carbonate) (PPC) is a biodegradable polymeric material which is co-polymerized from carbon dioxide and propylene oxide. Since carbon dioxide is a known greenhouse gas, the application of PPC is significant on the environmental protection. But poor properties such as thermal stability and mechanical property exhibited by PPC have limited its practical application. In this paper, (PPC)/organoPHilic montmorillonite (OMMT) and (PPC)/organoPHilic rectorite (OREC) nanocomposites were prepared by a melt blending method .Study concerning the aging and degradation of PPC is never reported. In this paper, the thermal oxidative aging of PPC/OMMT and PPC/OREC nanocomposites was investigated by the accelerated aging test; biodegradation of PPC/OMMT and PPC/OREC nanocomposites was investigated by the accelerated degradation test; and amidolysis of PPC/OREC nanocomposites was investigated at different temperature.The results of thermal oxidative aging showed that the aging properties of PPC were obviously improved by adding OMMT and OREC. The retention of mechanical properties of PPC/OMMT and PPC/OREC nanocomposites were higher than that of pure PPC after thermal oxidative aging. The improvement can be attributed to the layered structure of OMMT and OREC which acts as barriers, reducing oxygen diffusion through the samples during the aging.The results of biodegradation showed that the effect of OMMT and OREC on degradation was dependent on the content of the clay. The clay accelerated the degradation while the content of the clay was higher; and depressed the degradation while the content was lower.The results of amidolysis showed that OREC accelerates the degradation of PPC. At the room temperature, the films of pure PPC were amidolysed on the surface and inside; with the presence of OREC or at a lower temperature, amidolysis would process mainly on the surface of the films. It was dependent on the possibility that NH₃ penetrates the films from surface to inside.