Development of lightweight and thermally insulative crosslinked polypropylene via rotomolding

Abstract

In this study, lightweight and thermally insulative crosslinked polypropylene (xPP) parts were successfully produced for the first time using a straightforward dicumyl peroxide (DCP) crosslinking technique via rotational molding. A novel crosslinked and cellular structure was achieved by incorporating varying DCP contents (0.5–2.5 phr) during the rotomolding process. An increase in the DCP content led to a corresponding increase in both gel content and crosslink density, while leading to lower density. In particular, the addition of 2.5 phr DCP significantly increased the cell size by 33% (528–704 μm) and cell density by 540% (1.5–9.6 × 103 cells/cm3), while decreasing the density by 58% (0.902–0.378 g/cm3). Moreover, the thermal conductivity and resistivity (insulation power) were analyzed over a temperature range (23–120°C) for different applications. The results show that the crosslinked porous structure substantially improved the thermal resistance (691%) with a very low thermal conductivity (0.055 W/m K) at room temperature. This innovative approach not only represents a significant progress in the development of lightweight and insulative materials but also sets a benchmark for future research in the field of crosslinked polymer foams, opening the door for a wide range of applications, especially for rotomolded parts. Highlights: The effect of DCP content on the final properties was studied. The incorporation of DCP into PP within the rotomolding process led to novel structures. Lightweight and highly insulative porous structures were obtained. Temperature-dependent thermal conductivity was studied for various applications. The crosslinked porous structure significantly enhanced thermal resistance with very low thermal conductivity (0.055 W/m K) at room temperature.