Relationship between branch length and the compatibilizing effect of polypropylene‐g‐polystyrene graft copolymer on polypropylene/polystyrene blends

Abstract

Three polypropylene-g-polystyrene (PP-g-PS) graft copolymers with the same branch density but different branch lengths were evaluated as compatibilizing agents for PP/PS blends. The morphological and rheological results revealed that the addition of PP-g-PS graft copolymers significantly reduced the PS particle size and enhanced the interfacial adhesion between PP and PS phases. Furthermore, it is verified that the branch length of PP-g-PS graft copolymer had opposite effects on its compatibilizing effect: on one hand, increasing the branch length could improve the compatibilizing effect of graft copolymer on PP/PS blends, demonstrated by the reduction of PS particle size and the enhancement of interfacial adhesion; on the other hand, increasing the branch length would increase the melt viscosity of PP-g-PS graft copolymer, which prevented it from migrating effectively to the interface of blend components. Additionally, the crystallization and melting behaviors of PP and PP/PS blends were compared. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40126.

Effect of Different Compatibilization Systems on the Rheological, Mechanical and Morphological Properties of Polypropylene/Polystyrene Blends

“…As already assumed from SEM figures, the PP–PS 75:25 PODIC blend shows an almost identical average mean diameter value and standard distribution compared to the virgin blend. According to Wang et al [ 66 ], an increase in branch length could improve the compatibilizing effect leading to finer dispersed morphologies which would also be in good agreement with extensional viscosity measurement results indicating more pronounced strain hardening and the existence of long chain branches.…”

“…Detailed formation on the combined structure as well as the exact size and shape of particles are related to a complex mixture of impact factors like viscosity ratio, elasticity, polarity, interfacial adhesion, mixing and processing conditions [ 61 , 62 ]. Nevertheless, successful compatibilization has been reported by various authors to result in decrease of particle size and an overall more homogeneous structure for many polymer mixtures in various component ratios [ 63 , 64 , 65 , 66 , 67 , 68 ].…”

Morphology, thermal behavior, rheological, and mechanical properties of polypropylene/polystyrene blends based on elongation flow

“…The PP/PS blend is known as a typical, immiscible system, in which PP constitutes a partially crystalline phase and PS constitutes an entirely amorphous phase. Because very few molecular chains connect the two phases by traversing the interphase, the PP/PS blends usually result in serious phase separation with poor interfacial adhesion 11‐13 . Therefore, a lot of attempts have been carried out to improve the interfacial compatibility between the two phases of PP/PS blends 8,14‐21 .…”

The compatibilization effect of exfoliated graphene on rheology, morphology, and mechanical and thermal properties of immiscible polypropylene/polystyrene (PP/PS) polymer blends

“…1 –4 However, PP and PS are immiscible and incompatible polymers and their blends lead to poor mechanical properties due to low interfacial interactions. 5 –8 Many effective methods have been developed to compatibilize PP/PS blends such as using functionalized modifiers, synthetic block, graft copolymers (styrene-butadiene (SB), styrene-butadiene-styrene (SBS), and styrene-ethylene-butylene-styrene (SEBS)), and grafted polymers (PP-g-PS, PP-g-MAH, etc.) as compatibizer.…”