PS PE alloy research

Both polystyrene and polyethylene are the largest general-purpose plastics in terms of output. Polystyrene has the advantages of high modulus, high strength, transparency, easy processing and good dimensional stability. Its biggest disadvantage is that it is brittle and easy to crack. Polyethylene has good flexibility and high impact strength at room temperature, but its modulus is low. Use cheap PE to improve the brittleness of PS and improve its impact strength without significant loss of modulus.

PS and PE have great differences in chemical structure, solubility, polarity and quality, and they are incompatible with each other. The mechanical properties of simple binary blends, such as tensile strength and elongation at break, are lower than the composition average of the corresponding properties of PS and PE. Scanning electron microscope was used to observe the cross-section of a simple blend with a composition ratio of PS and PE of 8/2, and it was found that there was an obvious two-phase structure with clear interphase and gaps, which resulted in extremely poor mechanical properties.

The key to solving the above problems is to introduce a small amount of the third component-compatibility agent in the blending system. The role of the compatibilizer is to improve the interface condition and change the structure of the two phases. Specifically, it is to reduce the interfacial energy of the blend, reduce the size of the phase region, and increase the bonding force between the two phases. At the same time, the presence of the compatibilizer has a stabilizing effect on the microdomains, so that the microdomains do not aggregate during the processing and molding process.