Thermoplastic elastomers rheological studies

Even though thermoplastic elastomer has been widely studied [1-23], there has been relatively little serious research of the rheological behavior of the block copolymer systems [20-31]. Data on the effects of carbon black on the extrusion behavior are even more limited. In this work, we investigated the effects of carbon black on the triblock copolymer thermoplastic elastomers SBS (styrene-butadiene-styrene), SIS (styrene-isoprene-styrene), and SEES (styrene-ethylene/butylene-styrene). 

As previously mentioned, the growth of the block copolymer thermoplastic elastomer industry has now reached a high level of commercial importance. However, it is still difficult to study the rheological behaviors of thermoplastic elastomers because they exhibit complex behavior that combines the elastomeric final product properties with the processing characteristics of thermoplastics. Recently, the rheological behavior of the styrene block copolymers (SBS, SIS, and SEES) was studied by Kim and Han [31]. A series of systematic investigations for the viscoelastic behavior of triblock copolymer thermoplastic elastomers also were conducted by Mathew et al. [22,23]. Kim and Hyun [20] reported the viscoelastic properties of SEES. 

It is widely known that the advantage of NR-based thermoplastic elastomer over the NR is the ease of processing, subsequently resulting in lower cost of production. Melt rheology of NR and ethylene-vinyl-acetate copolymer (EVA) blends were studied by Koshy et al The melt rheology of the blends between NR and EVA has been studied with reference to the effects of blend ratio, crosslinking systems, shear stress, and temperature. It was found that a positive... 

Sivaraman, R, et ai. Thermoplastic copolyether ester elastomer toughened polycarbonate blends 2. Thermal and rheological studies. Polymer Tesfm, 23(6) p. 645. 2004. 

Hemmati M, Narimani A, Shariatpanahi H (2011) Study on morphology, rheology and mechanical properties of thermoplastic elastomer polyolefin (TPO)/carbon nanotube nanocomposites with reference to the effect of polypropylene-grafted-maleic anhydride (PP-g-MA) as a compatibilizer. Int J Polym Mater 60 384—397... 

Dynamically vulcanized thermoplastic elastomer (TPV)/organoclay nanocomposites based on EPDM/PP containing 2, 4, 6% of organically treated montmorillonite were prepared by using EPDM-g-MA and PP-g-MA as compatibilizer. Dicumylperoxide (DCP) and triallyl cyanurate (TAC) were employed as crosslinking system. X-ray diffraction (XRD) analysis has been performed to evaluate the extent of the intercalation.. In this study, attempts have been made to exclusively reinforce rubber dispersed phase. Rheological behavior and melt viscoelastic properties of the samples such as elastic modulus, and elastic response expressed in terms of relaxation time distribution, H (A), were studied. The results were also supported by differential scanning calorimetry (DSC) and mechanical tests. 

In the present study we utilized Plasticorder torque values (polymer viscosity) on a relative basis, principally to follow the course of thermoplastic polyurethane elastomer polymerization, and the effect of several relevant variables on this polymerization. These torque data, expressed in meter-grams, served our purposes well, and we have not attempted to translate them to absolute rheological units. Such translation, which is a rather complex problem, has been addressed by others using a different rotor type and other polymers in the Plasticorder.14 That study concluded that the shear rate, y, of the Brabender Plasticorder with a somewhat different rotor configuration (roller blade) is in the range of 23 - 228 sec 1 over the rotor speed range of 30 - 200 rpm. 

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