Sa. Xu et Cm. Chan, POLYSTYRENE HIGH-DENSITY POLYETHYLENE BLENDS COMPATIBILIZED BY A TRI-BLOCK COPOLYMER I - PROPERTIES AND MORPHOLOGY, Polymer Journal, 30(7), 1998, pp. 552-558
The compatibilization of polystyrene (PS)/high density polyethylene (H
DPE) blends was achieved by using a (styrene-ethylene/butylene-styrene
) tri-block copolymer (SEBS) as a compatibilizer. The blends were prep
ared by a twin-screw extruder. The mechanical properties of the blends
were greatly improved after addition of SEES, suggesting the compatib
ilizing role of the tri-block copolymer in the immiscible PS/HDPE syst
em. The morphology of the blends was observed by scanning electron mic
roscopy (SEM). It was found that the copolymer is very efficient in re
ducing the size of the dispersed phase, and that a co-continuous two-p
hase structure appears as the content of SEES increases to 4 wt%. The
results of a SEM study of the fracture surfaces of the tensile bars sh
owed that the unmodified and modified blends exhibited different fract
ure characteristics. The melt rheology of the blends was investigated
by capillary rheometry. The melt viscosity of the blends increases aft
er the addition of 4 wt% SEES. The thermal properties of these blends
were measured by a differential scanning calorimeter (DSC). The SEES c
ontent does not affect the glass transition temperature of the polysty
rene phase and the melting point of the polyethylene phase in the blen
ds.