Liquid Crystalline Polymers Compatibilization and Adhesion Enhancement by Reactive Blending in Post-Consumers PET&amp;rsquo;s

Aversa Raffaella,Apicella Antonio

doi:10.3844/ajeassp.2016.530.539

Abstract

A method for PET mechanical properties enhancement by reactive blending with HBA/HNA Liquid Crystalline Polymers for in situ highly fibrillar composites preparation is presented. LCP/PET blends were reactive extruded in presence of Pyromellitic Di-Anhydride (PMDA) and then characterized by Differential Scanning Calorimetry, Thermally Stimulated Currents and tensile mechanical properties. The formation of specific macromolecular structures, where the PET, the LCP and the reactive additive are involved, has been hypothesized in the reactively extruded blends from TSC analysis evidences. The use of a reactive additive improved the matrix LCP compatibilization and adhesion as indicated by the SEM analysis and mechanical testing. Moderate amounts of LCP in the PET (0.5 and 5%) and small amounts of thermo-active and reactive compatibilizer in the blend (0.3%) were found to significantly improve LCP melt dispersion, melts shear transfer and LCP fibril formation and adhesion. Blends of PET and LCP containing the compatibilizer favored the formation of a well dispersed and homogeneous fibrillar phase whose particle size distribution did not show great coarsening and coalescence leading to significant elastic properties improvements from 0.8 for not compatibilized to 3.1 GPa for compatibilized 0.5% LCP loaded PET blends that was even higher than those expected from ordinary theoretical calculation. This unexpected improvement was probably due to the presence of two distinct phases' supra-molecular structures involving PET-LCP and PMDA.

Highlights

Post-consumer Poly-Ethylene Terephthalate (PET) is principally coming from the recover of injection blow moulded bottles prepared using high intrinsic viscosity and molecular weight solid state upgraded fibre grade PET’s
Reactive extrusion was carried out on polymer blends of the PET and the LCP previously mixed in a twin extruder by adding the 0.3% of the poly-anhydride (PMDA)
The Scanning Electron Microscopy (SEM) analysis were run on the surfaces of the same PET/LCP blend samples with and without the reactive additive that have been fractured in tensile tests run at room temperature

Summary

Introduction

Post-consumer PET is principally coming from the recover of injection blow moulded bottles prepared using high intrinsic viscosity and molecular weight solid state upgraded fibre grade PET’s. Melt phases interactions and solid phases adhesion between the two components have been improved and controlled by a reactive alloying processes where the LC polymeric molecules containing potentially reactive groups (such as OH, NH and the like) are blended with PET based host polymers in presence of an anhydride specific reaction promoter.

Results

Conclusion