Cyclic extrusion of poly(butylene terephthalate)/organo‐montmorillonite nanocomposites: Thermal and mechanical retention properties

Poly(butylene terephthalate) (PBT) containing 3 wt % of organo-montmorillonite (OMMT) was prepared using twin screw extrusion followed by injection molding. The effects of thermal cycles (two times extrusion followed by injection molding) were studied on both PBT and PBT/OMMT nanocomposites. The samples were characterized by using tensile tests, flexural tests, field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), and dynamic mechanical thermal analysis (DMTA). The intercalation of the OMMT silicate layers in the PBT was confirmed using XRD. Both tensile and flexural modulus of PBT was improved by addition of OMMT. DSC results revealed that OMMT improved the crystallinity of PBT. The percentage retention in tensile and flexural properties of PBT/OMMT(E2) intercalated nanocomposites (i.e. two times extrusion followed by injection molding) is more than 96%. The melting temperature, crystallization temperature, and degree of crystallinity of PBT/OMMT(E2) is comparable with PBT/OMMT(E1) (i.e. one time extrusion followed by injection molding). This indicates that PBT/OMMT intercalated nanocomposites exhibit good retention-ability in mechanical and thermal properties after subjecting to two times twin-screw extrusion followed by injection molding. From the TGA results, it was observed that the thermal stability (e.g. Tonset) of PBT was reduced by the addition of OMMT. However, the addition of OMMT assists in the char formation of PBT. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008