Sa. Xu et Cm. Chan, POLYSTYRENE HIGH DENSITY POLYETHYLENE BLENDS COMPATIBILIZED BY TRI-BLOCK COPOLYMER II - TOUGHENING AND DEFORMATION MECHANISMS/, Polymer Journal, 30(9), 1998, pp. 691-696
A dilatometry method was applied to study the tensile deformation mech
anisms of polystyrene/high density polyethylene (80/20) blends compati
bilized by different amounts of a styrene-ethylene-butylene-styrene tr
i-block copolymer (SEBS). The volume change of the sample during uniax
ial tensile process, which was determined by two extensometers, was fo
und to be related to the various modes of deformation. To obtain quant
itative information on the separate contributions of several possible
deformation modes to the total deformation, a simple model proposed by
Dekkers and Heikens was used in this study. For comparison, the tensi
le behaviors of the pure polystyrene and high density polyethylene wer
e investigated also. The results indicated that elastic deformation wa
s the main deformation mode for pure polystyrene and the uncompatibili
zed blend; whereas, plastic deformation was found to play an important
role in a tensile process of the compatibilized blends. For the blend
containing 2 wt% SEES, the deformation process was very complex, craz
ing and shearing predominated alternatively in different ranges of str
ain. However, shearing was the main non-Hookean deformation mechanism
for the blends containing SEES content higher than 4 wt%. The differen
t deformation characteristics of the blends were related to their morp
hologies.