Mechanical properties of low-density polyethylene/nano-magnesium hydroxide composites prepared by an in situ bubble stretching method

Low-density polyethylene/nano-magnesium hydroxide (LDPE/nano-Mg(OH)2) composites have been prepared by an in situ bubble stretching (ISBS) method and simple shear method. By means of field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), it was confirmed that the ISBS method leads to a high degree of dispersion of the Mg(OH)2 nanoparticles in the LDPE matrix. Furthermore, no significant re-aggregation of the nanoparticles was observed after removing the bubbles by means of high-speed grinding. The tensile strengths of nanocomposites prepared by means of the ISBS method were higher than those of materials with the same Mg(OH)2 loading produced by direct blending/extrusion. The tensile strength of the nanocomposites produced by the ISBS method reached a maximum value at an Mg(OH)2 content of 15 phr. In contrast, the tensile strength of composites prepared by direct blending/extrusion shows a monotonic decrease with increasing Mg(OH)2 content. The improvement in mechanical properties of nanocomposites associated with the use of the ISBS method can be attributed to a more homogeneous dispersion of smaller nanoparticles.