Thermal and impact study of PP/PET fiber composites compatibilized with Glycidyl Methacrylate and Maleic Anhydride

In this paper, two grafted copolymers, Glycidyl Methacrylate grafted PP (PP-g-GMA) and Maleic Anhydride grafted PP (PP-g-MA), were used in polypropylene (PP) reinforced with poly (ethylene terephthalate) (PET) fiber composites. The composites were prepared by melt impregnation technique using a Brabender internal mixer. The composite strength results showed enhancement for both of modified composites up to 10wt% and this growth was bigger for GMA modified samples. The results of torque mixing supported the occurrence of compatibilization reaction between epoxy groups of GMA modified PP and PET end groups (hydroxyl and carboxyl). Heat deflection temperature (HDT) results of GMA modified composites revealed more enhancement than HDT of MA modified ones. DSC thermograms showed bigger area of melting peak for unmodified samples and it was found bigger area of melting peak for GMA modified composite than MA one’s. Transcrystallization (TC) of PP on PET fibers was investigated using a polarized optical microscope which revealed no TC for neither of modified composites at the fiber/matrix interface. The morphological analysis of GMA modified PP/PET composites pointed out a marked improvement of fiber dispersion and interfacial adhesion as compared to non-compatibilized PP/PET composites. It was perceived that strain at break tend to decrease by adding PET fibers and that decrement was more for modified samples. The impact strengths of composites versus fiber wt% were greater for unmodified composites up to 15 wt% of fibers due to having weaker interface. The impact results also disclosed that using either of these modifiers reduces the impact strength at low fiber percentages. According to linear elastic fracture mechanics (LEFM), toughness (GC) and stress intensity factor (KC) were evaluated for theses composites based on the fracture energy obtained from impact tests.

Keywords:

Composite , Poly (ethylene terephthalate) fiber , Compatibilization , polypropylene