Abstract
Different percentages of an elastomeric phase of styrene-ethylene-butylene-styrene (SEBS) were added to a polystyrene (PS) matrix to evaluate its nucleating effect in PS foams. It has been demonstrated that a minimum quantity of SEBS produces a high nucleation effect on the cellular materials that are produced. In particular, the results show that by adding 2% of SEBS, it is possible to reduce the cell size by 10 times while maintaining the density and open cell content of the foamed materials. The influence of this polymeric phase on the glass transition temperature (Tg) and the shear and extensional rheological properties has been studied to understand the foaming behavior. The results indicate a slight increase in the Tg and a decrease of the shear viscosity, extensional viscosity, and strain hardening coefficient as the percentage of SEBS increases. Consequently, an increase in the density and a deterioration of the cellular structure is detected for SEBS amounts higher than 3%.
Highlights
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Elastomeric phases, such as thermoplastic elastomers (TPEs), which present the elastic behavior of rubbery materials and the re-processability of thermoplastic polymers, have aroused the interest of the scientific community in recent years [1]
An elastomeric phase based on a SEBS copolymer was added to a PS matrix to evaluate its effect as a cell nucleating agent
The size of the dispersed domains increases when the amount of SEBS increases, and the rheological behavior of the formulations are significantly affected by the increase in the SEBS content
Summary
Elastomeric phases, such as thermoplastic elastomers (TPEs), which present the elastic behavior of rubbery materials and the re-processability of thermoplastic polymers, have aroused the interest of the scientific community in recent years [1]. Some examples of them are poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate)copolymers, known as MAM, styrene-butylene-styrene (SBS), and styrene-ethylene-butylenestyrene (SEBS). This last material presents high resistance to degradation, which makes it interesting for blending with common thermoplastic materials such as polypropylene (PP) or polystyrene (PS) [2]. The incorporation of this organic phase in common thermoplastic polymers has been reported by several researchers with successful results when modifying the impact properties of the solid polymer matrix. An increase in the PS content resulted in the lowering of the shear viscosity and energy requirements for mixing, indicating an easier flow and more sustainable processing [1]
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