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. 2023 Mar 17;15(6):1503.
doi: 10.3390/polym15061503.

The Cellular Structure and Toughness of Hydrogenated Styrene-Butadiene Block Copolymer Reinforced Polypropylene Foams

Wei Guo  1   2   3   4 , Zicheng Zheng  1   2   3   4 , Wei Li  4   5 , Hao Li  2   3   4   6 , Fankun Zeng  1   2   3   4 , Huajie Mao  2   3   4   6
Affiliations

The Cellular Structure and Toughness of Hydrogenated Styrene-Butadiene Block Copolymer Reinforced Polypropylene Foams

Wei Guo et al. Polymers (Basel). .

Abstract

Polypropylene nanocomposites containing varying amounts of Styrene-ethylene-butadiene-styrene block copolymer (SEBS) were prepared through the supercritical nitrogen microcellular injection-molding process. Maleic anhydride (MAH)-grafted polypropylene (PP-g-MAH) copolymers were used as compatibilizers. The influence of SEBS content on the cell structure and toughness of the SEBS/PP composites was investigated. Upon the addition of SEBS, the differential scanning calorimeter tests revealed that the grain size of the composites decreased, and their toughness increased. The results of the rheological behavior tests showed that the melt viscosity of the composite increased, playing a role in enhancing the cell structure. With the addition of 20 wt% SEBS, the cell diameter decreased from 157 to 66.7 μm, leading to an improvement in the mechanical properties. Compared to pure PP material, the impact toughness of the composites rose by 410% with 20 wt% of SEBS. Microstructure images of the impact section displayed evident plastic deformation, effectively absorbing energy and improving the material's toughness. Furthermore, the composites exhibited a significant increase in toughness in the tensile test, with the foamed material's elongation at break being 960% higher than that of pure PP foamed material when the SEBS content was 20%.

Keywords: SEBS; microcellular polypropylene; thermoplastic elastomer; toughening.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Figure 1
Figure 1
Supercritical microcellular foaming technology.
Figure 2
Figure 2
Schematic diagram of sample segmentation (S1: parallel section, S2: vertical section).
Figure 3
Figure 3
(a) Crystallization curve, (b) Melting Curve.
Figure 4
Figure 4
Crystal morphology under polarized optical microscope. ((a)—MPP; (b)—MPP/5%SEBS; (c)—MPP/10%SEBS; (d)—MPP/15%SEBS; (e)—MPP/20%SEBS).
Figure 5
Figure 5
Shear viscosity curves (a) general plot, (b) partial magnification at a low shear rate, and (c) partial magnification at a high shear rate.
Figure 6
Figure 6
Elastomer distribution: (a–d: solid, a’–d’: foamed). (a,a’: MPP/5%SEBS); (b,b’: MPP/10%SEBS); (c,c’: MPP/15%SEBS); (d,d’: MPP/20%SEBS).
Figure 7
Figure 7
Cell structure: (a)—MPP, (b)—MPP/5%SEBS, (c)—MPP/10%SEBS, (d)—MPP/15%SEBS, (e)—MPP/20%SEBS.
Figure 8
Figure 8
Cell structure parameters: (a) The cell diameter in the vertical section, (b) The cell density in the vertical section.
Figure 9
Figure 9
Impact profile and impact properties of foamed samples ((a)—MPP, (b)—MPP/5%SEBS, (c)—MPP/10%SEBS, (d)—MPP/15%SEBS, (e)—MPP/20%SEBS).
Figure 10
Figure 10
Schematic diagram of crack extension.
Figure 11
Figure 11
Tensile stress-strain curves of composite: ((a)—foamed sample; (b)—solid sample).
See this image and copyright information in PMC

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