Research Information System
Eurofillers 2013, Slovakia, 1 - 04 August 2013, pp.5-6, (Summary Text)
Polymer/clay nanocomposites have gained great importance, both in industry and in academia due to their remarkable properties [1]. In literature, there have been plenty of studies related to the preparation of PET/clay nanocomposites by in-situ polymerization and melt compounding. The extrusion method played very important role in preparing PET/clay nanocomposites due to its simple and versatile processing way. On the other hand, this method can potentially cause thermal decomposition of commonly used alkyl ammonium ions in modified clays, which caused further degradation of polymer matrix. In recent years, a method called “thermokinetic mixing” has begun to be employed for preparing polymer nanocomposites. The thermokinetic mixing system, which requires no external heating, is specifically designed to handle difficult compounding and dispersion applications within a few minutes [2].
In this work, thermal decomposition behavior and morphology development of the poly(ethylene terephthalate) (PET) and its nanocomposites generated with organically modified clays using different processing methods. To achieve this goal, an intercalating agent (quaternary ammonium salt) was synthesized and two types of montmorillonite clay (Rockwood clay CEC: 90–100 meq/100 g, Resadiye clay CEC: 70 meq/100 g) modified with this intercalating agent was mixed with the PET (Melinar B60, intrinsic viscosity (IV): 0.820 dl/g) by employing melt extrusion (Leistritz Micro 27 LG 44D, diameter = 27 mm, L/D = 44) and high shear mixing (Gelimat ,Dreiswerke USA) method. We then compared the nanocomposites in terms of dispersion and thermal stability properties. Our results showed that changing the processing type from extruder to thermokinetic mixer reduced the clay particle size substantially. The results from the SEM analyses (Fig. 1) are in excellent agreement with those obtained from the investigation of XRD data. Larger shear rates induced during thermokinetic mixing process were revealed to be responsible for a better dispersion of the clay mineral. The results show that manganese in the raw clay –though chemically bound- leads to decreased IV values, i.e. decreased molecular weight in PET/organoclay nanocomposites. It was revealed that working on the thermokinetic mixer provided substantial contributions such as shorter processing times elimination of drying step before melt processing, less thermal degradation more homogeneous and better dispersion of the clay particles in PET matrix phase.