Effects of Flame Retardants Additives on the Properties of Low-Density Polyethylene

Abstract

Low-density polyethylene (LDPE) has many unique properties such as lightweight and high chemical resistance. Unfortunately, it burns rapidly when it is exposed to a flame which limits its applications especially when flame resistance is to be considered. Different percentages of magnesium hydroxide and decabromide diphenyl ether (3.0, 5.0, 7.0, and 9.0 wt.%) were mixed with LDPE using a two-roll mill machine at 160⁰C for 2 minutes. Then, the tensile and flame retardancy tests samples were prepared by an injection molding process using an industrial plastic machine at 160⁰C. Flammability, rheological, tensile and thermal properties of the produced samples were tested using a flammability test apparatus, a melt flow index machine, a universal testing machine, and a differential scanning calorimeter, respectively. It was observed that the flame resistance of LDPE was improved with the addition of both flame retardants up to 7.0 wt.%, then it was reduced when 9.0 wt.% of flame retardants were used. This may be attributed to the poor mixing due to the increase in the polymer melt viscosity as observed from the melt flow index results. An increase in elastic modulus and a reduction in ductility of LDPE were observed with the increasing of flame-retardant contents while the ultimate tensile strength of LDPE was increased from 5.7 to 7.6 and 7.5 MPa when 9.0 wt.% and 7.0wt.% decabromide diphenyl ether and magnesium hydroxide were added. This is due to the fact that the additives act as a load carried and/or their effects on the degree of crystallinity of LDPE.