Effects of the molecular structure of impact modifier and compatibilizer on the toughening of PBT/SBS/PS‐GMA blends

Abstract

This work aims at studying the toughening process of poly(butylene terephthalate) (PBT) through its blends with styrene-butadiene-styrene block copolymers (SBS), in the presence of poly(styrene-ran-glicydil methacrylate) (PS-GMA) as reactive compatibilizer. High values of impact strength were attained for PBT/SBS blends without the compatibilizer; however, this improvement is achieved for blends with SBS having similar viscosity compared to PBT, at high SBS content (40 wt %) and for blends prepared under specific processing conditions. The efficiency of the in situ compatibilization of PBT/SBS blends by PS-GMA was found to be strongly dependent on the SBS and PS-GMA molecular characteristics. Better compatibilizing results were observed through fine phase morphologies and lower ductile to brittle transition temperatures (DBTT) as the interfacial interaction and stability of the in situ formed compatibilizer are maximized, that is, when the miscibility between SBS and PS-GMA and reaction degree between PBT and PS-GMA are maximized. For the PBT/SBS/PS-GMA blends under study, this was found when it is used the SBS with higher polystyrene content (38 wt %) and with longer PS blocks (M w ¼ 20,000 g mol À1) and also the PS-GMA with moderate GMA contents (4 wt %) and with molecular weight similar to the critical one for PS entanglements (M c ¼ 35,000 g mol À1).

Morphology and properties of PBT/SEBS and PBT/SEBS-G-MAH blends

“…As we all know, the appearances of two glass transitions are clear evidence of phase separation, and that of a single glass transition at a temperature intermediate between those of the pure components indicates miscibility [14,23] Plots of dynamic loss (tan δ) and storage modulus as a function of temperature for the PBT/SEBS and PBT/SEBS-G-MAH blends are given in Figure 2 and 3. There are two transition temperatures (Tg1 and Tg2) were observed for PBT/SEBS blend, the sharp dynamic mechanical damping peak at about 70 is a result of the glass transition of PBT component, and the broad peak near 110 is associated with the glass transition temperature relaxation of the polystyrene (PS) component in the SEBS [8].…”

“…These characteristics make it very useful for manufacturing injection-molded articles for domestic, electrical, and automotive applications where the above mentioned characteristics are required [12]. The un-notched impact strength of PBT is high, however, it is strongly notch sensitive and gives brittle fracture [13][14][15].…”

Characterization of clay filled poly (butylene terephthalate) nanocomposites prepared by solution blending

“…PBT is a semi crystalline engineering thermoplastic with some superior properties like high crystallization rate, chemical and thermal resistance, high impact strength, low molding temperature and excellent processing. Due to these superior properties, PBT has wide application in automotive, electronic, electric and packaging industry [11][12][13][14] . Clay/PBT nanocomposites have been studied by many researchers.…”

Compatibilizing Action of a Poly(styrene–butadiene) Triblock Co-polymer in ABS/PET-G Blends

“…Several patents consider blends based on poly(ethylene terephthalate (PET) [4][5][6][7], and poly(acrylonitrile-co-butadiene-co-styrene)(ABS) [8][9][10][11][12][13]. Recently, Xue et al [14] studied miscibility and compatibilization of poly(trimethylene terephthalate)/poly(acrylonitrilebutadiene-styrene) blends.…”