Study of Dimensional Changes depending on Moisture Sorption of Change in Polymeric Materials for Automotive Exterior Lamp

Abstract

Moisture sorption behavior and dimension change of polymeric materials (ASA, ABS, PMMA, PC, PP, PPS) for automotive exterior lamp has been investigated. The variations of the moisture sorption have been represented following the theoretical model of the Fick's 2nd law of diffusion. In order to understand the dimensional change during the moisture sorption process, the change in length of each sample was studied. The length of polymeric materials increased as equilibrium water content increased. The moisture absorbed polymer materials provided a 33% decrement of the coefficient of thermal expansion, seemingly by swelling the polymer materials under atmosphere condition.

Reducing Moisture Absorption in Polypropylene Nanocomposites for Automotive Headlamps Using Hydrophobicity-Modified Graphene/Montmorillonite

“…In addition, studies have been conducted to analyze the moisture absorption and desorption properties of polymeric materials that can cause fogging in automotive headlamps [5][6][7]. Bielecki et al [5] proved that the condensation on the surfaces in the lamp did not solely originate from the water vapor present in the air, and the moisture in the plastic components of the lamp significantly contributed to this phenomenon.…”

“…Therefore, condensation formation in automobile lamps seems to be directly linked to the hygroscopicity of the plastic housing. Later, Kim et al studied the moisture absorption and moisture desorption of polymeric materials applied to exterior automotive lamps [6,7].…”

“…However, polymers are mechanically less resistant than metallic materials, which limits their applications. Moreover, most polymers absorb moisture, which changes their physical properties [6,8]. For products that are exposed to the atmosphere, investigations on their ability to absorb atmospheric moisture are significant.…”

“…For products that are exposed to the atmosphere, investigations on their ability to absorb atmospheric moisture are significant. Crucially, the water absorbed by polymeric materials or composites causes structural changes as it penetrates the free volume of the polymer; for example, micropores are reversibly generated during moisture absorption and desorption [6,7].…”