Vitrimers are a relatively new class of materials which form a "bridge" between classical thermosets and thermoplastics. These materials are covalently crosslinked, but rather than being permanent, the crosslinks are dynamic and may rearrange upon heating above the so-called vitrimer transition temperature. This leads to a greater dimensional stability and creep resistance at lower temperatures and (re)processability of the materials at higher temperatures. Recently we reported our results on the development of a new type of semi-crystalline vitrimer based on poly(butylene terephthalate) (PBT). Glycerol was incorporated as a crosslinker into the amorphous phase of PBT via solid-state polymerization using Zn<sup>2+</sup> as a transesterification catalyst. It was found that the crystallization characteristics of PBT were not significantly affected by the incorporation of glycerol, leading to similar thermo-mechanical properties below the melting point. Above the melting point, however, a rubbery plateau was observed (consistent with a crosslinked material) and the modulus of this rubbery plateau could be changed by changing the amount of crosslinker. The dynamic nature of the crosslinks was confirmed via stress relaxation experiments, revealing a full relaxation at temperatures above the melting point. Furthermore, it was found that the (thermo)mechanical properties could be further tuned by using different crosslinkers and/or changing the morphology of the material. These results will be discussed in detail in the current presentation.

Semi-crystalline vitrimers via solid state polymerization

256th National Meeting (2018)

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