Extruded Polystyrene Foams with Enhanced Insulation and Mechanical Properties by a Benzene-Trisamide-Based Additive

Low thermal conductivity and adequate mechanical strength are required when extruded polystyrene foams are used as insulation materials. Compared to large cell XPS foams with cell sizes greater than 100µm, small cell XPS foams with cell sizes smaller than 10µm have the same density and offer better mechanical and insulating properties due to their microcellular morphology. Therefore, most research is based on reducing the size of cells to achieve structural optimization.

In this study, we improved the thermal insulation and mechanical properties of extruded polystyrene foam by controlling the morphology of foam nucleating agent 1,3, 5-phenyltriamide. The structure-property relationship of extruded polystyrene foam was established. The influence of cell size and foam density on thermal conductivity was evaluated by using polystyrene foam with different concentrations of phenyltriamide. The results showed that the addition of phenyltriamide reduced the thermal conductivity by up to 17%. The increase of foam density leads to higher compression modulus of foam. The compression modulus increased from 11.7 ± 2.7 MPa of pure polystyrene (PS) to 46.3 ± 4.3 MPa of 0.2 wt % phenyl-triamide under the action of 0.2 wt % phenyl-triamide. The increase of modulus has a power law relationship with foam density. In addition, the compression modulus was normalized from foam density to evaluate the effect of benzene - triamide alone. The 0.2wt % benzene-triamide increased the normalized compression modulus by about 23%, which may be attributed to the additional stress contribution of the nanofibers and may also delay the surface stretching and edge bending of the foam.

DOI:10.3390/polym11020268