Study on preparation of highly dispersed graphite composite expandable polystyrene foam by homogeneous dissolution-suspension polymerization with waste polystyrene

Graphite expandable polystyrene (GEPS) has the advantage of low thermal conductivity, however, the disadvantage of the low compatibility with styrene and a tendency to agglomerate, which limits the application of GEPS in the thermal insulation industry. In this article, the high-dispersion GEPS beads were prepared by homogeneous dissolution-suspension polymerization method. Then, the GEPS beads were foamed, molded, and cured to form GEPS foam boards. The characterization results of IR, scanning electron microscope, X-ray diffraction, and thermogravimetric analyzer of GEPS beads, the microporous structure, water absorption, flexural strength, compressive strength, and oxygen index of GEPS foam board show that the performance is equal to or exceeds corporate expandable polystyrene. In particular, the thermal conductivity of GEPS foam (0.034 W/(mk)) is 10.5% lower than that of corporate EPS (0.038 W/(mk)). In addition, it is noteworthy that the dissolution of waste expandable polystyrene or polystyrene beads reaches up to 45% of the styrene monomer mass, while the enterprise can dissolve only 5.2%.