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Annealing of polypropylene/poly(ethylene‐co‐propylene) blend. II. Influence of the structure and properties of poly(ethylene‐co‐propylene) and blended polyethylene on impact strength
Author(s) -
Ito Junichi,
Mitani Katsuo,
Mizutani Yukio
Publication year - 1985
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1985.070300205
Subject(s) - materials science , comonomer , ultimate tensile strength , crystallinity , annealing (glass) , izod impact strength test , polyethylene , composite material , amorphous solid , glass transition , microstructure , melting point , polypropylene , polymer blend , vicat softening point , polymer chemistry , polymer , softening point , polymerization , chemistry , organic chemistry , copolymer
The effect of annealing on the impact strength of PP/poly(ethylene‐co‐propylene) (PEP) and PP/PEP/PE blends was studied with regard to the structure of PEP and the polyethylene crystallinity. The tensile impact strength of annealed blends was remarkably affected by the PEP structure such as molecular weight and comonomer composition and the annealing temperature, while the brittle temperature was scarcely affected. For the PP/PEP/PE blends, annealing at temperatures above the melting point of PE lowers the tensile impact strength in a similar manner as the PP/crystalline PEP blend. These phenomena were explained on the basis of the deformation mechanism presented in the previous article, that is, a thicker interfacial layer of PP and PEP forms by means of annealing to increase the energy needed to deform the interface. By using a scanning electron microscope, the transition layer was observed at the interface between amorphous PEP and PE in the PP/amorphous PEP/PE blend after etching with nitric acid. The formation of a thicker transition layer between amorphous PEP and PE and a sizeable increase in PE particle size by annealing was observed. The phenomena should be correlated with the impact sensitivity, especially tensile impact strength, in the PP/crystalline PEP and PP/amorphous PEP/PE blends. A reasonable explanation of the microstructure in PP/PEP blends has been developed in terms of comonomer composition and melting property of PEP.