Abstract
Silk is a natural material with excellent thermal resistance and mechanical properties and has traditionally been utilized primarily in textile applications. Direct incorporation of silk into polypropylene (PP) via injection molding has raised concerns regarding the formation of agglomerates (lumps) due to inadequate dispersion. In polymer compounding, it is well established that the addition of substances such as water can enhance the dispersibility of additives within the resin matrix. Recent studies have also reported that silk, when exposed to temperatures exceeding 170 °C, undergoes dehydration-induced thermal decomposition, resulting in the generation of superheated vapor.
In this study, we aimed to suppress the formation of silk agglomerates by leveraging the superheated vapor generated from silk, thereby enhancing the thermal and mechanical performance of the resulting composite. These results demonstrated that silk was uniformly dispersed within the PP matrix, leading to the desired enhancement in composite properties. The key to achieving this outcome was the optimization of the compounding temperature to 210 °C. Notably, silk exhibited the capacity to retain water up to this elevated temperature, effectively functioning as an intrinsic “water reservoir.” This finding reveals a novel characteristic of silk that contributes to its potential as a functional additive in polymer composites.
