Molecular level stabilization of poly(ethylene terephthalate) with nanostructured open cage trisilanolisobutyl-POSS

A nanostructured organometallic macromer trisilanolisobutyl-POSS (T-POSS) was used to prevent discoloration of poly(ethylene terephthalate) (PET) and to achieve molecular level stabilization during melt processing. The resultant material was investigated using thermal analysis and oscillatory rheology. The interaction between the PET and the nanostructured additive was investigated using X-ray photoelectron spectroscopy (XPS) and matrix-assisted laser desorption/mass spectrometry (MALDI-MS). Thermal studies show that the additive increases the thermooxidative stability and consequently prevents discoloration of the material. Rheological data demonstrate increased shear storage modulus with the addition of T-POSS to PET, indicating better melt elasticity and a broader window of processability of the material. The XPS and MALDI-MS results confirm that the stabilization is achieved by covalent interaction and branching of the nanostructured additive to PET.