The Effect of Functionalized SEBS on the Properties of PP/SEBS Blends

Abstract

Styrene (St) was used as comonomer and glycidyl methacrylate (GMA) as grafting monomer to prepare SEBS-g-(GMA-co-St) graft copolymers via melt grafting. Then, the graft copolymers were employed as a compatibilizer for melt blending polypropylene (PP) and hydrogenated styrene-butadiene-styrene (SEBS) triblock copolymers. The effects of the amount of GMA in the graft copolymers on thermal properties, rheology, crystallization, optical and mechanical properties, and microstructure of the blends were investigated. The results show that GMA and St were successfully grafted onto SEBS. The GMA amount in the graft copolymer significantly influenced the comprehensive properties of PP/SEBS/SEBS-g-(GMA-co-St) blends. The epoxy groups of GMA reacted with PP and SEBS, forming interfacial chemical bonds, thereby enhancing the compatibility between PP and SEBS to varying extents. After introducing SEBS-g-(GMA-co-St) into PP/SEBS blends, crystallinity decreased, crystal size increased while transmittance remained above 91% with rising GMA amount in the graft copolymers, indicating excellent optical properties. Notched impact strength and elongation at break of the blends showed a trend of first increasing and then decreasing with increased amounts of GMA in the graft copolymers. When the amount of GMA in the graft copolymers was 3 wt%, the blends exhibited optimal toughness with notched impact strength and elongation at break of 30,165.82 J/m2 and 1445.40%, respectively. This was attributed to the tightest dispersion interface adhesion and maximum matrix plastic deformation, consistent with the mechanical performance results.

A pragmatic approach to analyze the ability of ethylene‐octene copolymer in the long chain branching of polypropylene in molten and solid state

“…Specifically, long‐chain branching (LCB) significantly affects the melt response to a stretching flow, leading to the strain‐hardening phenomenon 79 . When the nonlinear data exceeds the linear curve at certain points, the melt is termed strain hardening, caused by the restricted stretching of the backbone between the branch points connecting the branches 52,53 . This behavior is observed in all modified samples at all Hencky strain rates, as depicted in Figure 9.…”

“…Various methods are available for analyzing the degree of branching in polymers, which can be used independently or in conjunction with other experiments to analyze the data. Some of methods of measuring grafting efficiency include analyzing the chemical composition distribution, crystallization kinetics study, molar mass characterization, and dynamic mechanical analysis 53 . In one of the recent studies, Hoffman–Lauritzen analysis of crystallization was performed for PP samples measured by optical microscopy 54 .…”

The Effect of Thermoplastic Elastomer and Fly Ash on the Properties of Polypropylene Composites with Long Glass Fibers

“…To distinguish the samples, two relaxations can be seen in the loss factor vs. temperature and loss modulus vs. temperature curves of PP composites reinforced with glass fiber or a mixture of glass fiber and treated fly ash. Another relaxation can be seen in Figure 5d exclusively on the curves for composites containing elastomer, PP-25G-E and PP-25G-C-E. E peak 1 is only found in PP-25G-E and PP-25G-C-E because it corresponds to the Tg of the elastomer (olefin block) [52], whereas E peak 2 is associated with the glass transition of PP (Tg) and E peak 3 is associated with the lamellar slip and rotation in the crystalline phase of PP [53]. The tan δ curves of the samples exhibit three distinct relaxation peaks that correspond to the peaks of the loss modulus.…”