In recent years, automotive front headlamps have gradually become heavier as various functions have been added, and housing materials require light weight along with high rigidity. Moreover, when using the front headlamp, the difference between the internal temperature of headlamp and the external temperature of headlamp causes fogging. This in turn occurs because of the moisture inside the headlamp’s components, thereby requiring strategies to mitigate moisture absorption of such components. The moisture condensing inside the headlamp is attributed to moisture contained inside plastic parts such as the housing, lens holder, or bezel. The moisture resistance of polymers can be improved by mixing an inorganic lamellar filler with an aspect ratio sufficient to alter the diffusion path of water molecules. Polymer composites have attracted attention because international environmental and fuel efficiency regulations require lightweight automotive systems. Polypropylene (PP) is a commercial polymer that is widely used in several industries owing to its low cost and light weight. In particular, PP–MF composites are used in the internal, external, and electric components of automotives, owing to their low cost and excellent formability. PP–MF composites are used in the headlamps’ housing components and are thought to be the primary source of moisture in headlamps. PP-talc composites, which are hydrophobic and have a low moisture absorption per unit weight, are the heaviest plastic parts of the headlamp and are considered to be the main source of moisture in the headlamp. In this study, flake-shape nanofillers based on MMT and graphene was manufactured for use in PP nanocomposite materials with low moisture absorption and excellent mechanical properties. The moisture absorption characteristics, mechanical properties, and part formability of the produced PP nanocomposite were investigated, analyzed, and compared with the current commercial PP-MF composite. Through the hydrophilicity control of the nanofiller, the moisture absorption of PP nanocomposites was lowered by up to 10%. Considering the moisture absorption, mechanical properties, and cost, the PP/MMT-G nanocomposite showed the best performance in this study. Thus, the designed nanocomposites are expected to help mitigate headlamp fogging while reducing weight.
Dr. Pyoung-Chan Lee, Principal Researcher, Korea Automotive Technology Institute