Styrene-acrylonitrile thermal aging

Thermal Oxidative Stability. ABS undergoes autoxidahon with the polybutadiene component moie sensitive, to theimal oxidation than tire styrene-acrylonitrile component. Antioxidants substantially improve oxidative stability. Studies on the oven aging of molded parts have shown that oxidation is limited to the outer surface (<0.2 mm), i.e., the oxidation process is diffusion limited. 

Polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) represents a typical blend that from its commercial introduction in the 1960s has become a major material in the automotive industry, as well as applications in business machine and electronic sectors. The blends provide the balance of properties required for these applications at an economic cost. These include low temperature ductility/impact and processability including injection moulding, extrusion and thermoforming. The commercial growth has been maintained by developments in heat stability, thermal ageing in hot wet environments and halogen free flame retardency [8]. 

This study was therefore undertaken to prepare and evaluate acrylonitrile—butadiene-styrene (ABS) and methyl methacrylate-butadiene-styrene (MBS) polymers under similar conditions to determine whether replacement of acrylonitrile by methyl methacrylate could improve color stability during ultraviolet light aging, without detracting seriously from the good mechanical and thermal-mechanical properties of conventional ABS plastics. For purposes of control, the study also included briefer evaluation of commercial ABS, MBS, and acrylonitrile-butyl acrylate-styrene plastics. 

The behavior of the two-phase systems is complex and responses on aging can be affected by the thermal history and aging temperature. This is well illustrated by a series of investigations, the two-phase blend of acrylonitrile-butadiene-styrene copolymer (ABS, Tg = 110 °C) and polycarbonate of bisphenol-A (BPAPC, Tg = 151 °C). Due to the phase-separated structure of the blend, two enthalpy recovery peaks are detected by enthalpy relaxation and attributed to the two components (Tang and Lee-SuUivan 2008). However, aging appears to have little effect on the ABS component even at temperatures close to the ABS glass transition. 

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