Preparation and properties of flame retarded ramie/phenolic resin composites

The ramie fabric was treated with two different types of flame retardants, namely phosphate type and nitrogen-phosphorous type, and composed with phenolic resin to prepare ramie/phenolic resin laminate. The flame retardancy of the laminate treated by nitrogen-phosphorous type flame retardant is better than that treated by phosphate type flame retardant. The limiting oxygen index (LOI) of the laminate with nitrogen-phosphorous type treatment increases from 25.2% to 39.1%, and reaches the V0 level in UL94 vertical burning test, while LOI of the laminate with the phosphate type treatment only increases to 27.8%. Cone calorimeter tests show that the laminates with the nitrogen-phosphorous type treatment have increased char residue, extended ignition time and decreased peak heat release rate and average smoke density. It is also found that the mechanical properties of the laminates are not changed because of the little damage on the fiber structure of ramie fabric with the flame retardant treatment.