Effect of cross-linking on the mechanical properties, degree of crystallinity and thermal stability of polyethylene vitrimers

Maleic anhydride-grafted-polyethylene was dynamically cross-linked via reactive melt blending with 4,4'-dithiodianiline. Thermal and mechanical properties of polyethylene vitrimers with different cross-linking density were investigated. The results indicate that the degree of crystallinity decreased with increasing cross-linking density. This behavior was directly related to short-term and long-term mechanical properties: vitrimers showed a decrease in yield strength and creep performance. The yield strength of PE vitrimers decreased linearly in relation to the degree of crystallinity. Polarized optical microscopy revealed that the cross-links inhibit the growth of spherulites structure in polyethylene vitrimers. Thermogravimetric analysis indicated an increase in the onset degradation temperature and decomposition rate for vitrimers with increased cross-linking density. The stiffness of the vitrimers decreased with increasing cross-linking density which led to higher damping properties. Finally, it was demonstrated that reprocessing of polyethylene vitrimer was possible without significant impact in mechanical properties. KEYWORDS cross-linking, mechanical properties, polyethylene, reprocessing, structure-property relations, thermal properties, vitrimers
1 | INTRODUCTION Polyethylene (PE) is presently the most-used commodity plastic by volume and it is frequently used in consumer goods, construction, and electrical industry. [1,2] Some examples include plastic [...]