Abstract
The effect of ultraviolet radiation on styrene-ethylene-butadiene-styrene (SEBS) has been studied at different exposures times in order to obtain a better understanding of the mechanism of ageing. The polymer materials were mechanically tested and then their surfaces were analyzed using a scanning electron microscope (SEM) and atomic force microscopy (AFM). Moreover, the optical analysis of contact angle (OCA) was used to evaluate the surface energy (γs) and the yellowing index (YI) and attenuated total reflectance infrared spectroscopy (ATR–FTIR) were used to observe structural and physical changes in aging SEBS. The results obtained for the SEBS, in relation to the duration of exposure, showed superficial changes that cause a decrease in the surface energy (γs) and, therefore, a decrease in surface roughness. This led to a reduction in mechanical performance, decreasing the tensile strength by about 50% for exposure times of around 200 hours.
Highlights
Styrene-ethylene-butadiene-styrene (SEBS) is considered a thermoplastic elastomer (TPE); these materials combine the easy processing characteristic of a thermoplastic with the physical properties of a vulcanized rubber [1,2]
The effect of UV exposure time on the chemical structure, as well as on the mechanical and morphological properties of SEBS, in order to test the behavior observed in the aged mechanical and morphological properties of SEBS, in order to test the behavior observed in the aged material was analyzed
The degradation of SEBS caused by accelerated aging results in structural changes to the material associated with the appearance of polar groups, mainly carboxyl, structural changes to the material associated with the appearance of polar groups, mainly carboxyl, carbonyl, and hydroxyl groups
Summary
Styrene-ethylene-butadiene-styrene (SEBS) is considered a thermoplastic elastomer (TPE); these materials combine the easy processing characteristic of a thermoplastic with the physical properties of a vulcanized rubber [1,2]. SEBS is obtained by the hydrogenation process of styrene-butadiene-styrene (SBS) that breaks the unsaturated bonds of the polybutadiene chain, and the result is a transparent material with a higher resistance to aging that is used in areas such as medical instruments, orthopedic appliances, toys, protective materials, polymer modified bitumen (PMB), and so on [3,4]. TPEs, like organic polymers, degrade under environmental conditions owing to solar radiation and the presence of oxygen [5]. Aging depends on the butadiene/styrene ratio and block structure, owing to radial block structures having faster aging than linear block structures, this behavior can be slowed down using carbon nanotubes in SBS copolymer [11]. Tomacheski et al [12] studied the use of antimicrobial metal such as silver to protect
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