Application of PMI foam structure: After proper high te […]
Application of PMI foam structure:
After proper high temperature treatment, PMI foam can withstand high temperature composite material curing process requirements, which makes PMI foam widely used in the aviation field. The medium density PMI foam has good compression creep properties and can be cured by autoclave at a temperature of 120oC-180oC and a pressure of 0.3-0.5MPa. PMI foam can meet the creep performance requirements of the usual prepreg curing process, and can achieve co-curing of the sandwich structure.
PMI foam as an aerospace material is a uniform rigid closed-cell foam with a pore size that is basically the same. PMI foam can also meet FST requirements. Another feature of the foam sandwich structure compared with the NOMEX® honeycomb sandwich structure is that its moisture resistance is much better. Because the foam is closed-cell, moisture and moisture are difficult to enter into the core. Although the NOMEX® honeycomb sandwich structure can also be co-cured, it will reduce the strength of the composite panel.
In order to avoid core crushing or lateral displacement of the honeycomb during the co-curing process, the curing pressure is usually 0.28-0.35 MPa instead of the usual 0.69 MPa for laminates. This will lead to higher porosity of the composite panel. In addition, because the pore diameter of the honeycomb structure is large, the skin is supported only at the position of the honeycomb wall, which will cause bending of the PMI foam fiber and reduce the strength of the composite skin laminate.