Nanofillers, such as carbon nanotubes (CNTs), carbon nanofibers (CNFs), and graphene are used to improve properties of polymers used in consumer products. The potential release of nanofillers from consumer products across their life-cycle have significant impacts. Exposure to nanofillers exhibited human and eco-toxicities. Therefore, it is important to understand the effects of photolysis, photooxidation and thermal degradation on environmental ageing of polymer composites and the release of nanofillers.<br/>We studied nano-composites of polyethylene, epoxy-CNT and -CNF, and polypropylene-CNT. Changes in the physical, thermal and chemical properties of nano-composites during weathering were investigated using TGA, DSC, and FTIR. The effects of weathering on morphological changes of nano-composites were investigated using an optical microscope and SEM. The release of nanomaterials from polymer composites was observed with a dynamic light scattering (DLS) technique, TEM, and quantified by advanced ICP-MS technology.<br/>The thermal property of different nano-composites was significantly affected by weathering due to photooxidation and thermal decomposition, resulting in a decrease in melting and recrystallization temperatures with increasing exposure times to solar light. The surface of aged composites became rough with many cracks and as the surface of the polymers matrix degrades more nanofillers were observed on their surface. The FTIR analyses showed photooxidation resulted in the rise of the carbonyl index of the surface materials causing significantly high levels of -OH and C=O functional groups on surface molecules. TEM, DLS, and advanced ICP-MS analyses demonstrated the release of different materials from aged composites, including nanomaterial itself, polymer itself, and micropolymers containing nanomaterials. The changes in properties were used to develop an empirical-mechanistic surface-bulk erosion model to explain the degradation mechanism. The toxicities of the released nanomaterials were compared with pristine ones. We will present the results of property changes, nanomaterials release, and their toxicity.

Nano-composite degradation and the release of nanoparticles from consumer products during accelerated weathering

254th National Meeting (2017)

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