Tensile properties of styrene-ethylene-butadiene-styrene toughened and glass fiber reinforced polyethylene

Abstract

Polyethylene composites reinforced with glass fibers and elastomer-toughened with styrene-ethylene-butadiene-styrene were prepared using extrusion and then compression molded to form tensile bars conforming to the ASTM D-638 testing standards. Varying amounts of glass fibers and SEBS elastomers were incorporated into the sample in order to determine its effect on the tensile properties of the composites.

Through the test results, it was revealed that strengthening and toughening of the polyethylene composites were not achieved. Instead of increasing yield strength with increasing glass fiber contents, reductions in yield strength of the samples and presence of voids were observed. The main reason for this surprising discovery is due to the poor interfacial adhesion between the fiber-matrix interfaces, whose main purpose is to transmit stresses from the weak matrix to the stronger fiber. The reasons for the unusual trends in tensile properties of the composites are discussed in detail in this report.

In addition, it was discovered that 5 wt% SEBS actually caused the composite to fracture at low elongation at break values. However, at 10 wt% SEBS, there was a slight improvement in elongation compared to the corresponding non-elastomer-toughened sample. Under the SEM, it was discovered that there was no distinct 2 phase core shell structure, which is necessary for the toughening of polymers. Hence, it can be argued that higher amounts of SEBS are required to achieve a toughening effect.