TITLE:
Toughening of Immiscible rPS/SAN Blends by SEBS Elastomers: Properties and Morphology
AUTHORS:
Khaled Bedjaoui, Rodrigo Navarro, Rachida Krache, Juan Lopez Valentin, Rebeca Herrero Calderon, Alberto Fernandez Torres, Angel Marcos Fernandez
KEYWORDS:
Recycled Polystyrene, SAN, Toughening, Polymer Blends, Rheology
JOURNAL NAME:
Journal of Materials Science and Chemical Engineering,
Vol.10 No.3,
March
28,
2022
ABSTRACT: In this research, an attempt
was made to improve compatibility in a polymer blend composed of incompatible
constituents, namely, recycled polystyrene (rPS) and polystyrene-co-acrylonitrile
(SAN), through the addition of a compatibilizer. The compatibilizing agent, styrene-ethylenebutadiene-styrene block
copolymer (SEBS), was added to the polymer blend in ratios of 5 and 10 wt%. For this purpose, blends of rPS and SAN
at different ratios, without and with
varying concentrations of compatibilizer, were prepared by melt blending using a co-rotating twin-screwextruder. Mechanical
properties including tensile and impact strength, rheological properties (RPA),
thermal behaviour (DSC) and morphological characteristics (SEM) were evaluated.
According to the results obtained by complex viscosity, the blends behave as a pseudoplastic
fluid. The results showed that the addition of SEBS increased the Izod impact
strength and the elongation at break and decreased the tensile strength and
tensile modulus. rPS/SAN blend modified with SEBS had better mechanical
properties than the rPS/SAN alloy. SEM photographs revealed that the SEBS was
not only distributed in the SAN phase but also distributed in rPS phase in
rPS/SAN/SEBS blend. Furthermore, DSC analysis for blends of rPS/SAN gave a good
indication of the improvement on miscibility for most compositions. SEM
micrographs of tensile fracture surfaces indicated that the formation of the
co-continuous phase and the improvement of interface adhesion are the most important
reasons for the excellent tensile properties of the rPS/SAN/SEBS blends. Within
the range of analysed compositions, the morphologies investigated by SEM are
typical of immiscible blends.