Poly(ethylene terephthalate)/polyethylene composite based on in-situ microfiber formation

Poly(ethylene terephthalate) (PET) microfiber was in-situ formed by compounding PET with polyethylene (PE) through a single screw extruder of a Haake rheometer system, where a rod die with comparatively smaller diameter (2.1 mm) was used, and the extrudate was drawn in a certain drawing ratio (3.1:1) and quickly cooled in cold water. Subsequently, the in-situ PET/PE composite was injection molded into specimens at temperatures that were lower than the melting temperature of the PET to keep the original shape of the PET fibers. The result from morphology observations of the composite showed that when the die diameter of the extruder is 2.1 mm and the drawing ratio of the extrudate is 3.1:1, PET was more or less changed into microfibers. The PET almost changed into fibers when the concentration was 15 wt%. concentrations below and above which decreased the fiber content. For the PET/PE blend prepared by conventional mixing technology, the dispersed PET formed spheres and no microfibrilar structure were found. The reinforcing effect of the PET fibers on the corresponding composite was significant at 15 wt% PET concentration observed from the correlation between the PET content and the tensile properties of die PET/PE in-situ composite. Besides, in general, the tensile strength and modulus of the composite increased with die PET concentration, and was higher than the conventional PET/PE blend without microfibers.