In situ microfibrillar-reinforced composites of isotactic polypropylene/recycled poly(ethylene terephthalate) system and effect of compatibilizer

Recycled poly(ethylene terephthalate) from waste bottles (hereafter, rPET) was used as an reinforcing material for isotactic polypropylene (iPP) based on the concept of in situ microfibrillar-reinforced composites (iMFCs). Microfibers of rPET were successfully generated during melt-extrusion and subsequent drawing and preserved in the final injection-molded specimens. The effects of draw ratio, initial size of ground rPET flakes, and rPET content on morphological appearance of the extrudates and the as-formed rPET fibers and mechanical properties of the as-prepared iMFCs were investigated. The results showed that diameters of the as-formed rPET fibers decreased with increasing draw ratio, and the initial size of ground rPET flakes did not affect the final diameters of the as-formed rPET fibers nor the mechanical properties of the as-prepared iMFCs. Flexural modulus, tensile modulus, and tensile strength of iPP/rPET iMFCs were improved by the presence of rPET microfibers and further improvement could be achieved by the addition of maleic anhydride-grafted iPP (PP-g-MA), which was used as the compatibilizer. (c) 2006 Wiley Periodicals, Inc.