Effect of composition and phase inversion in PET/PE-LD and PET/PP blends on their
mechanical and rheological properties and morphological structure
Polimery 2002, No 4, 250
The effect of composition (in its full range) of PET/PE-LD and PET/PP mixes on their static mechanical properties, rheological properties and structure was investigated. It was concluded that tensile strength (σM) and flexural strength (σfM), elasticity modulus (Et) and flexural modulus (Ef), elongation at break (εB) and Charpy notched impact strength (acU) (Figs. 1—6) change abruptly with composition of the blends. Abrupt changes have been recorded upon exceeding 40% by weight content of PET in the PE-LD blend and 25% by weight in the PP mix. Meil viscosity of both blends drops — also abruptly — with increase in PET content (Fig. 7). Abrupt changes in mechanical and rheological properties of the investigated systems are caused by phase inversion, confirmed by SEM microscopic images (Figs. 10 and 11). In blends with dominating polyolefin content (90% by weight PE-LD) factures are ductile and fibrous (Fig. 8), whereas domination of PET (95% by weight) givers brittle fractures (Fig. 9).
Keywords: poly(ethylene terephthalate), low-density polyethylene, polypropylene, polymer blends, mechanical properties, rheological properties, morphological structure, phase inversion