Preparation and Characterization of Thermoplastic Elastomers/Plasticizer - Compatibilizer/Organoclay Nanocomposites by Reactive Extrusion System

Abstract

Polymer layered silicate nano-composites were prepared in melt by reactive extrusion (25:1 21 mm Rondol twinscrew compounding line) using poly(ethylene-co-propylene- co-ethylidenenorbornene) terpolymer (EPDM) as a matrx polymer, PP-g-MA and poly[(maleic anhydride-alt-1-octadecene)-g-PEO (poly(MA-alt-OD)-g-PEO) as functionalized polymer compatibilizer-internal plasticizer, octadecyl amine-montmorillonite (ODA-MMT) and dimethyldidodecyl ammonium -MMT (DMDA-MMT) as reactive and non-reactive nano-fillers, respectively. The formation of nano structural fragments, polymer blend composition-properties (thermal behavior and morphology) was studied using FTIR, XRD, TGA-DTG and DSC analysis methods. It was found that intercalation/exfoliation degree of EPDM macromolecules significantly depends on the origin and content of organoclays. Better results were obtained for nanocomposites prepared in the presence of reactive organo-filler (ODA-MMT) and PEO grafted alternating copolymer. The results of FTIR (chemical structure) and XRD (physical structure and exfoliation degree) analyses indicate that amidization of anhydride copolymer with alkyl amine groups of organo-filler and esterification of alternating copolymer with α -hydroxy- ω -methoxy- PEO occur in melt compounding in situ processing in the chosen extrusion conditions (barrel temperature: 120, 130, 140 and 145°C, twin-screw speed around 30-40 mrp). The glass-transition (Tg), melting (Tm) and recrystallization (Tc) temperatures strongly depend on the origin and content of organoclay and PEO-grafted copolymer-compatibilizer, respectively. Thermal behavior, crystallinity and thermostability of nanocomposites were significantly improved as compared with pristine EPDM terpolymer.