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Summary Red phosphorus (RP) was used to improve the fire performance of wood flour – low density polyethylene (LDPE) composites containing ammonium polyphosphate (APP). The fire performance of LDPE‐based composites was investigated by using limiting oxygen index (LOI), UL‐94 standard, thermogravimetric analysis, and cone calorimeter. The addition of 30 wt% APP increased the LOI value from 17.5 to 24.2 and still burned to clamp (BC) in UL‐94 test. The RP showed beneficial effect when combinedly used with APP. The maximum beneficial effect was seen at ratio of 5:1 (APP : RP) with the highest LOI value of 27.2 and UL‐94 rating of V0. RP showed its beneficial effect via increasing the gas phase action of the flame retardant system. Copyright © 2015 John Wiley & Sons, Ltd.

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Two types of terpolymers, maleic anhydride (MA) and glycidyl methacrylate (GMA) functionalized, are used as compatibilizer in low-density polyethylene-wood flour composites. The type and amount of compatibilizer on the tensile, impact, morphological, and water absorption properties of composites are investigated. The effect of preimpregnation with a compatibilizer solution is also studied. The MA functionalized compatibilizer increases the mechanical properties of composites, when it is used either directly or with preimpregnation. GMA functionalized compatibilizer is not as effective as MA functionalized compatibilizer giving rise to small improvements in properties. An important point is doubling of the modulus with MA preimpregnated compatibilizer. With both compatibilizers the water absorption value of composites are reduced and the preimpregnation with both compatibilizers do not change the total amount of absorbed water with respect to the non-preimpregnated ones.

In the current study, the flame retardant woodplastic composites (WPC) were produced by reducing the flammability of both the wood flour (WF) and the matrix material. Accordingly, WF was treated either with bis[tetrakis (hydroxymethyl) phosphonium] sulfate (THPS) or with dicyandiamide-formaldehyde-phosphoric acid flame retardants (DFP). The synergistic mixture of ammonium polyphosphate (m-APP) was used to improve the flame retardancy of matrix material based on low density polyethylene (LDPE). The flame retardant properties of LDPE based composites were investigated using limiting oxygen index (LOI), UL-94 standard, thermogravimetric analysis (TGA), and cone calorimeter. The addition of 30 wt% m-APP increased the LOI value from 17.5 to 24.2 and still burned to a clamp (BC) in UL-94 test. The THPS and DFP treatments of WF did not have any remarkable effects on the flammability properties (LOI and UL-94 ratings) with respect to LDPE/WF/APP composite. According to cone calorimeter test results, the treatments of WF with THPS and DFP improved the fire performance with approximately 25 % reduction in total heat evolved (THE) with respect to LDPE/WF/APP. The high reduction in THE value demonstrated that there was an increase in the fire performance of the LDPE based composites when THPS or DFP treated WF was used with m-APP due to the increase in the amount of foamed char providing barrier effect.