Improvement of Mechanical Properties of LDPE by Reactive Extrusion of ABS Secondary Material

In this paper, PM (physical mixture) with LDPE/ABS ratio of 75:25 and CM (chemical mixture) with LDPE/ABS /MA ratio at 75:25:5 were prepared by twin-screw extruder. The ABS used is the secondary material of the electronic product shell treated by physical means to improve the mechanical properties of  PE.

Figure 1 is the SEM diagram of PM and CM sections, PM shows obvious two phases, ABS phase is dispersed in PE matrix, yellow dotted circle shows obvious pits, indicating that ABS and PE are debonded under stress, and red dotted line shows a smooth plane, indicating that there is no ABS distribution. All this shows that the two phases of the physically mixed PM are not well compatible. On the other hand, PM is a continuous rough surface, which shows that ABS and PE have good compatibility and can be enhanced.

Fig. 1 SEM diagram of PM and CM sections PM (left); CM (right) 

Fig. 2 is the stress-strain curve (a) and Young's modulus diagram (b) of PE, PM, CM and ABS, which are used to characterize the mechanical properties of the materials. It can be seen from fig. 2A that the ultimate fracture strength of CM is obviously higher than that of PM, and the ultimate fracture strength of PM is even lower than that of PE, this is because ABS improves the ultimate fracture strength of PE, but due to the poor compatibility of ABS in PM, the material produces defects and reduces the mechanical properties. Fig. 2B shows that the Young's modulus of PE reinforced by ABS increases obviously, and the effect of CM is more obvious, which is also in line with the conclusion of SEM diagram.

Fig. 2 stress-strain curves (a) and Young's modulus diagrams (b) of PE, PM, CM and ABS