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The effect of annealing at 135° on the mechanical properties of injection molded high density polyethylene‐polypropylene blends
Author(s) -
Varin R. A.,
Djokovic D.
Publication year - 1988
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760282208
Subject(s) - materials science , composite material , ultimate tensile strength , polypropylene , annealing (glass) , high density polyethylene , polyethylene , young's modulus , modulus , elastic modulus , polymer blend , tangent modulus , polymer , copolymer
The effect of annealing at 135°C for 5 hours on the tensile properties of mechanically mixed and then injection molded high density polyethylene (HDPE) and polypropylene (PP) blends has been investigated. Both the tangent elastic modulus and the tensile strength at yield exhibit a non‐linear behavior versus blend composition with a minimum of properties typical for incompatible blends. Annealing substantially improves mechanical properties of pure components and blends (20 percent increase in the yield strength of pure components and blends and the modulus of pure components, and ∼40 percent increase in the modulus of 50/50 blends) but the property behavior versus composition is still nonlinear. Scanning electron microscopy studies of fracture surfaces of blends seems to indicate some improvement in bonding between phases as a result of annealing, Both the elastic modulus and yield strength fit extremely well to the modified “rule of mixtures” equation in the general form: M b = M PE φ PE + M PP φ PP + ΔM PE/PP φ PE φ PP where M b is the blend property, M PE and M PP are properties of pure PE and PP components, φ PE and φ PP are weight fractions of PE and PP, and Δ M PE/PP is the interaction term being a measure of the deviation from simple additivity.