Effect of injection molding on structure and properties of poly(styrene‐ethylene‐butylene‐styrene) and its nanocomposite with functionalized montmorillonite

Abstract

In this paper, the effects of injection molding on structure and properties of poly(styrene-ethylene-butylene-styrene) (SEBS) and its nanocomposite with a functionalized montmorillonite (FMMT) were illustrated by comparison with the results of hot pressing. The injection-molded SEBS and its FMMT nanocomposite have a skin-core morphology with FMMT platelets more preferentially aligned along the sample plane, while hot-pressed samples not. The injection-molded samples also have a dense structure, and a less extent of microphase separation. In the injection molding process, the high shear flow coupled with solidification in presence of temperature gradient and high pressure in the closed cavity greatly affect the morphology and structure of the SEBS and its nanocomposites. The results also indicate attractive interaction between the soft segments of SEBS and the long alkyl silane chain grafted to FMMT, which allows FMMT to form a macroscopic network structure after the high-speed and high-pressure injection molding. The SEBS/FMMTinjected nanocomposite have the highest tensile strength and the best corrosion resistance, which can be attributed to the dense skin-core structure, stronger SEBS/FMMT interaction and the preferentially aligned FMMT platelets.

Adhesive Performance at Polymer–Substrate Interfaces in Nanoinjection Molding: Comprehensive Simulations from Molding to Failure

“…5,6 In nanoinjection molding, interface bonding strength is considered a key property of composite materials, with lowperforming interfaces often leading to extensive failure in the interface structure of the composite material. Li et al 7 investigated the impact of injection molding on the structure and properties of poly(styrene-ethylene-butylene-styrene) (SEBS) and its nanocomposites with functionalized montmorillonite (FMMT). It showed that the long alkyl silane chains grafted to FMMT exhibited favorable interactions with the soft segments of SEBS, resulting in the formation of a better SEBS/ FMMT interface.…”

Scalable methods for directional assembly of fillers in polymer composites: Creating pathways for improving material properties

“…Several conventional polymer processing techniques, including fiber spinning, [97] film blowing, [98] and uniaxial stretching, [103] can be employed to introduce sufficient mechanical force for orienting fillers within the composite. Shearing is also involved in injection molding, [104][105][106][107] plate shearing, [108] and roll-milling, [109][110][111] which can provide an alternative mechanism to develop directional assembly of particles in the polymer matrix. Additionally, application of external fields can polarize fillers, resulting in their alignment within a matrix along the field direction.…”

Injection molding and shear‐induced stress simulation of poly (styrene‐ethylene‐butylene‐styrene) and polypropylene blends

“…Sengupta et al 20 found that the PP phase can be dispersed into the polystyrene domain under high strain, and can be oriented together with SEBS to increase the elongation of the ternary blend. Our previous work found that due to the high‐shear flow, injection‐molded SEBS and its nanocomposite have a skin‐core morphology, and the relaxation of molecular chains is limited by the mold, the degree of microphase separation is greatly reduced, and the tensile strength and corrosion resistance are greatly reduced 21 . In injection molding, high‐speed shear can untie the entangled molecular chains of the triblock copolymer, reduce its melt viscosity, improve its mold filling ability, and obtain good mechanical properties 22 .…”

“…Our previous work found that due to the high-shear flow, injection-molded SEBS and its nanocomposite have a skin-core morphology, and the relaxation of molecular chains is limited by the mold, the degree of microphase separation is greatly reduced, and the tensile strength and corrosion resistance are greatly reduced. 21 In injection molding, high-speed shear can untie the entangled molecular chains of the triblock copolymer, reduce its melt viscosity, improve its mold filling ability, and obtain good mechanical properties. 22 However, the anisotropy caused by shearing makes the polymer chain in an unbalanced stress conformation, 23 which is prone to form microscopic defects and macroscopic dimensional changes under external stimulation.…”