Polymer blends composed of low-density polyethylene (LDPE) as a disper
sed phase, polystyrene (PS) and poly(2,6-dimethyl-1,4-phenylene oxide)
(PPO) constituting a matrix phase and a small amount of block copolym
er rene-block-ethylene-co-butene-block-styrene)(SEBS) as a compatilize
r were studied for exploring deformation mechanism. The blend specimen
s prepared via solution-melt procedure were observed by transmission e
lectron microscopy (TEM) under in-situ stretching. For the blend with
PS matrix, crazing initiated by the dispersed LDPE is the deformation
mode while micro-shear yielding becomes dominate when a certain amount
of PPO is incorporated. In the latter case, the LDPE particles within
the deformation zones deform to ellipsoids indicative of the molecula
r orientation in the microbands. The variation of the deformation mode
can be attributed to the change of entanglement density of the matrix
with changing composition of PS and PPO.